Carman scan ONE application

1
Carman scan ONE application
2
CONTENT

• CRANK ANGLE SENSOR
• CAM POSITION SENSOR
• TPS
• AIR FLOW SENSOR
• OXYGEN SENSOR
• INJECTOR
• IGNITION
• ISC VALVE
• AIR TEMPERATURE SENSOR
• COOLANT TEMPERATURE SENSOR
• BATTERY VOLTAGE
• KNOCK SENSOR
• VEHICLE SPEED SENSOR
• EGR VALVE
• CANISTER PURGE VALVE
• OXYGEN SENSOR HEATER

3
CRANK ANGLE SENSOR-1 CHECK METHOD

• With connecting the Oscilloscope, Set the
  Sampling rate to over 250KHz and Compare the
  Counts and width of tooth between Long tooth
  after measuring the Crank Angle signal when
  Engine trouble is appearing.
•  
• lt Reference gt This signal must be measured on
  over 250KHz sampling rate at least. In case of
  low memory capacity, Measuring time is very
  short. Thus It must be measured on time of
  appearing the Engine trouble as triggering the
  signal. But it is difficult to catch on time of
  Engine trouble.

NOTICE Ground line should be earth to engine or
chassis to see the absolute signal.
4
CRANK ANGLE SENSOR-2

• 1.   Find and connect the Signal and Ground line
  referencing the wiring diagram.
• 2.   After measuring the Signal, Compare the
  measured signal with Normal Signal.
• 3.    Check if Operating of Related components
  with this signal is Normal through checking the
  normal condition value of components
• lt Related components gt
• 1.  Injector Timing and working status.
• 2. Ignition timing and working status
• 3. Synchronization with CAM angle signal

5
CRANK ANGLE SENSOR-3 WAVE ANALYSIS

• WAVE ANALYSIS-MAGNETIC TYPE-1
• When the target wheel (The ring that has teeth)
  pass by the magnetic crankshaft sensor, electric
  pressure is generated during cutting the lines of
  magnetic force. The shorter the distance between
  crankshaft sensor and the target wheel (air gap)
  is and the higher the engine revolution is high
  electric pressure is generated. The longer and
  the slower, low electric pressure is generated.

6
CRANK ANGLE SENSOR-4

• WAVE ANALYSIS-MAGNETIC TYPE-2
• ECU can recognize tooth signal not by means of
  peak signal but by means of rising edge and
  falling edge.
• That is, if the output voltage of the magnetic
  sensor is over about 20mV ECU determines ON, if
  about 5 -10mV ECU determines OFF, and finally
  ECU recognize one ON/OFF cycle as one tooth.

7
CRANK ANGLE SENSOR-5

• WAVE ANALYSIS-MAGNETIC TYPE-3
• If noise is occurred and ECU recognizes this
  noise signal as real tooth signal, ECU cannot
  detect long tooth or detect more increased short
  tooth and it results in fuel cut and ignition
  cut. So when noise is exist, it must be checked
  abnormal injection.

8
CRANK ANGLE SENSOR-6

• WAVE ANALYSIS-MAGNETIC TYPE-4
• The level change (Edge from high to low level/
  from low to high level) of the camshaft signal
  must be occurred at least two short teeth before
  from the long tooth.
• If the level change of the camshaft signal is
  occurred at long tooth or at short tooth before
  one tooth from the long tooth, We must check
  pulley (TDC) position and modify it.

9
CRANK ANGLE SENSOR-7

• WAVE ANALYSIS-HALL TYPE-1
• This one is hall type sensor and circuit is
  included within sensor and 12V power is supplied.
  If metal is passed the sensing part within
  1.00.5mm gap, 5V (or 12V with another sensor)
  output voltage is generated through sensor
  internal circuit.

10
CRANK ANGLE SENSOR-8

• WAVE ANALYSIS-HALL TYPE-2
• ECU can recognize tooth signal not by means of
  peak signal but by means of rising edge and
  falling edge.
• That is, if the output voltage of the magnetic
  sensor is over about 200mV 2.5V ECU determines
  ON, if about 100mV 1.5V ECU determines OFF, and
  finally ECU recognize one ON/OFF cycle as one
  tooth.

11
CRANK ANGLE SENSOR-9
lt When ignition wave is occurred during crank
angle signal ON gt

• WAVE ANALYSIS-HALL TYPE-3
• If noise is occurred and ECU recognizes this
  noise signal as real tooth signal, ECU cannot
  detect long tooth or detect more increased short
  tooth and it results in fuel cut and ignition
  cut. So when noise is exist, it must be checked
  abnormal injection.

12
CRANK ANGLE SENSOR-10
lt When ignition wave is occurred during crank
angle signal OFF gt
lt When ignition wave is occurred at the beginning
of crank angle signal ON (or OFF) gt
WAVE ANALYSIS-HALL TYPE-4
13
CRANK ANGLE SENSOR-11

• WAVE ANALYSIS-HALL TYPE-5
• The level change (Edge from high to low level/
  from low to high level) of the camshaft signal
  must be occurred at least two short teeth before
  from the long tooth.
• If the level change of the camshaft signal is
  occurred at long tooth or at short tooth before
  one tooth from the long tooth, We must check
  pulley (TDC) position and modify it.

14
CRANK ANGLE SENSOR-12

• WAVE ANALYSIS-OPTICAL TYPE-1
• This is an optical sensor. During round plate (It
  is called target wheel) that has holes is
  revolved with camshaft, the light is shone. If
  the light passes through the hole, out put
  voltage is generated. This sensor uses this
  principle and need power to be operated.

15
CRANK ANGLE SENSOR-13

• WAVE ANALYSIS-OPTICAL TYPE-2
• ECU can recognize tooth signal not by means of
  peak signal but by means of rising edge and
  falling edge.
• That is, if the output voltage of the magnetic
  sensor is over about 200mV 2.5V ECU determines
  ON, if about 100mV 1.5V ECU determines OFF, and
  finally ECU recognize one ON/OFF cycle as one
  tooth.

16
CRANK ANGLE SENSOR-14

• WAVE ANALYSIS-OPTICAL TYPE-3
• If noise is occurred and ECU recognizes this
  noise signal as real tooth signal, ECU cannot
  detect long tooth or detect more increased short
  tooth and it results in fuel cut and ignition
  cut. So when noise is exist, it must be checked
  abnormal injection.

17
CRANK ANGLE SENSOR-15

• WAVE ANALYSIS-OPTICAL TYPE-4
• The level change (Edge from high to low level/
  from low to high level) of the camshaft signal
  must be occurred at least two short teeth before
  from the long tooth.
• If the level change of the camshaft signal is
  occurred at long tooth or at short tooth before
  one tooth from the long tooth, We must check
  pulley (TDC) position and modify it.

18
CRANK ANGLE SENSOR-16 FIELD EXAMPLE
lt Example 1 gt Vehicle New Sephia 1.5L SOHC,
Odometer 7,200Km Problem description Engine
is started with hesitating. Engine is stopped
soon after starting in cold ambient condition and
restart is hard. Cause Power, which is
supplied, to distributor is cut during very short
time when key is released after engine start.
This phenomenon cause abnormal crank angle signal
and it result in engine problem.
Signal measurement
19
CRANK ANGLE SENSOR-17

• Explanation When key is released after engine
  start, ECU doesnt inject fuel due to missing
  crank angle signal by the bouncing
  phenomenon(Repeat contact and non-contact)
• Enlargement of application The change of sudden
  engine speed is due to injection fuel cut or
  abnormal ignition timing control. Most of this
  phenomenon is case that ECU doesnt acquire
  normal crank angle signal, so crank angle sensor
  signal should be checked whether it is normal or
  not. And ignition timing and fuel injection
  control should be checked at the same time.
•  
• A.  In case of back-fire occurrence of LPG
  vehicle
• B.  In case that engine stall is suddenly
  occurred in idle sate
• C.  In case that engine vibration is
  intermittently occurred
• D. In case that engine is started with
  hesitating as jamming flywheel in self motor

20
CRANK ANGLE SENSOR-18

• lt Example 2 gt
• Vehicle Sephia 2 1.5L SOHC, Odometer 24,000Km
  / Credos 2.0L DOHC LPG
• Problem description
• - Gasoline vehicle Engine is started after
  hesitating during ?0.5sec as jamming flywheel
  in self-motor or engine is not started with the
  phenomenon.
• - LPG vehicle Backfire is happened when engine
  start.
• Cause Injector opening phase is abnormal and
  ignition timing is controlled with intake stroke.

Signal measurement
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CRANK ANGLE SENSOR-19

• Explanation When flywheel is jammed in
  self-motor with initial engine cranking,
  vibration is occurred. ECU regard it as tooth
  signal and then first normal crank signal is
  acquired as long tooth. It results in wrong TDC
  calculation in ECU and abnormal fuel injection
  time and ignition timing control.
•  
• Enlargement of application It is example that
  is occurred by wrong acquisition of ECU. Even
  though signal is normal, in case that ECU
  acquires it as abnormal signal, trouble may be
  detected. Therefore if injection time and
  ignition timing control is out of normal range,
  crank angle signal should be.
• A. In case of back-fire occurrence of LPG vehicle
• B. In case that engine stall is suddenly occurred
  in idle sate
• C. In case that engine vibration is
  intermittently occurred
• D. In case that engine is started with hesitating
  as jamming flywheel in self motor

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CRANK ANGLE SENSOR-20

• lt Example 3 gt
• Vehicle Avella / Sephia 1.5L SOHC/DOHC ,
  Odometer 24,000Km / Credos 1.8L/2.0L DOHC LPG
  Taxi (Optical distributor equipped)
• Problem description Engine stall is occurred at
  times and once the problem is happened it is
  repeated many times. And after maintaining normal
  state for long time, engine stall is suddenly
  occurred. And then engine is not started.
• Cause Crank angle signal is occasionally missed
  or noise is occurred.

Signal measurement
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CRANK ANGLE SENSOR-21

• Explanation In case of missing crank angle
  signal and noise occurrence, ECU recognize wrong
  tooth number. At this time injection and ignition
  is cut until tooth number is identified. If tooth
  number is corrected during injection and ignition
  cut, it is started again but engine stall may be
  occurred before ECU recognize it.
•  
• Enlargement of application In case of sudden
  engine stall without abnormal engine operation,
  it is due to mainly abnormal crank angle signal.
  In this case, crank angle signal, injection time
  and ignition timing should be checked together
  and if missing injection or ignition is found
  out, check noise occurrence after amplifying
  crank angle signal.
• A. In case of back-fire of LPG vehicle
• B. In case that engine stall is suddenly occurred
  in idle sate
• C. In case that engine vibration is
  intermittently occurred
• D. In case that engine is started with hesitating
  as jamming flywheel in self motor

24
CAM POSITION SENSOR-1 CHECK METHOD

• With connecting the Oscilloscope, Set the
  Sampling rate to over 250KHz and Compare the
  Counts and width of tooth between Long tooth
  after measuring the Cam Angle signal when Engine
  trouble is appearing.
•  
• lt Reference gt This signal must be measured on
  over 250KHz sampling rate at least to see the
  effect for noise. In case of low memory capacity,
  Measuring time is very short. Thus It must be
  measured on time of appearing the Engine trouble
  as triggering the signal. But it is difficult to
  catch on time of Engine trouble

NOTICE To measure the signal, ground line
should be earth to chassis or engine.
25
CAM POSITION SENSOR-2

• 1.   Find and connect the Signal and Ground line
  referencing the wiring diagram.
• 2.   After measuring the Signal, Compare the
  measured signal with Normal Signal.
• (1) Find the Rising point and Falling point of
  Cam signal through the tooth counts of crank
  angle signal.
• (2) Calculate the high and low level of cam
  signal as the crank angle sensor signals tooth
  counts.
• 3.   Check if Operating of Related components
  with this signal are Normal through checking with
  the normal condition value of components.
• lt Related components gt
• 1.  Injector Timing and working status.
• 2.  Ignition timing and working status

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CAM POSITION SENSOR-3 WAVE ANALYSIS

• Magnetic type
• Sensor signal voltage is as following graph.

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CAM POSITION SENSOR-4

• lt Reference gt
• The high and low phase change of Cam signal must
  be generated before long tooth of the crank
  signal that is at least 3 short teeth before.

28
CAM POSITION SENSOR-5

• WAVE ANALYSIS-Optical type
• This is an optical sensor. During round plate
  (It is called target wheel) that has holes is
  revolved with camshaft, the light is shone. If
  the light passes through the hole, out put
  voltage is generated. This sensor uses this
  principle and need power to be operated.

29
CAM POSITION SENSOR-6

• The level change (Edge from high to low level/
  from low to high level) of the camshaft signal
  must be occurred at least two short teeth before
  from the long tooth.
• If the level change of the camshaft signal is
  occurred at long tooth or at short tooth before
  one tooth from the long tooth, We must check
  pulley (TDC) position and modify to make cam
  signal level change at least 2 short teeth before
  from the long tooth.

30
CAM POSITION SENSOR-7

• WAVE ANALYSIS-Hall type
• This one is hall type sensor and circuit is
  included within sensor and 12V power is supplied.
  If metal is passed the sensing part within
  1.00.5mm gap, 5V (someone is 12V) output voltage
  is generated through sensor internal circuit.

31
CAM POSITION SENSOR-8

• The level change (Edge from high to low level/
  from low to high level) of the camshaft signal
  must be occurred at least two short teeth before
  from the long tooth.
• If the level change of the camshaft signal is
  occurred at long tooth or at short tooth before
  one tooth from the long tooth, We must check
  pulley (TDC) position and modify to make cam
  signal level change at least 2 short teeth before
  from the long tooth.

32
CAM POSITION SENSOR-9 FIELD EXAMPLE

• Vehicle Avante 1.5L DOHC, Odometer 48,000Km
• Problem description When acceleration during
  driving, the performance is lack. And trouble
  code of camshaft angle sensor is detected at
  times.  
• Cause The trouble of camshaft angle sensor is
  due to no change of polarity between two
  validated long tooth. The acceleration
  performance is lack because camshaft sensor is
  assembled with 6?CRK retard.

Signal measurement
33
CAM POSITION SENSOR-10

• Explanation In case that ignition timing is
  controlled by ECU, crankshaft and camshaft signal
  should exactly synchronized. Check the problem
  after comparing with normal crankshaft and
  camshaft signal.
•  
• Enlargement of application If camshaft edge is
  close to long tooth detection point, it means
  that ignition timing is retarded. So, performance
  is decreased. If it is opposite case, it means
  that ignition is advanced and it results in
  knocking, lack of performance and engine damage.

34
TPS-1 CHECK METHOD

• 1. Check the Signal voltage with connecting the
  Oscilloscope.
• 2. After connecting the Hi-scan, Check that
  HI-scan detected the Idling state without
  stepping on the accelerator pedal.
•  
• ltConnecting Methodgt
• To measuring the Noise and Resistance throughout
  TPS wiring line exactly, That must be measured on
  not Connector side but closest position to ECU
  (within 30mm).
• -  TPS Signal line, TPS Ground line

NOTICE To measure the signal, ground line
should be earth to chassis or engine
35
TPS-2

• 1. Find and connect the Signal and Ground line
  referencing the wiring diagram.
• 2.  After measuring the signal, compare the
  measured signal with Normal signal.
• (1) After checking in IDLE state, Measuring the
  signal at WOT (Whole Open Throttle) as stepping
  on the accelerator pedal.
• (2) It prefers to check the Air mass flow signal
  in the same time if possible.
• lt Checking item gt
• (1) Check that IDLE state is well recognized
  through the Scanner.
• (2) Check that TPS signal value changed exactly
  according to Throttle variation.
• (3) Check that TPS adaptation value is learnt
  well in IDLE state.

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TPS-3 WAVE ANALYSIS

• Check the output voltage according to the pedal
  opening degree.

lt Spec. Specification which used during
development period gt
37
TPS-4

• lt Measurement Measure the mass air flow and TPS
  during full acceleration from idlegt
•  
• ECU recognized TPS signal check is essential.
  Through the scanner, TPS value vs. TPS adapted
  value check is required during idle. If TPS value
  is bigger (around 1.2) than adapted value, engine
  idle can be unstable due to ECU not recognized
  idle status.

38
TPS-5 FIELD EXAMPLE

• lt Example 1 gt The problem by noise
• Vehicle Matiz, Odometer 4,800Km 
• Problem description RPM cycling is sometimes
  taken place in idle state with engine vibration.
  And a lot of CO emission(1.7) comes from exhaust
  gas in idle state.
• Cause RPM cycling is taken place because ECU
  doesnt recognize idle state by noise detection
  of TPS signal. Whenever noise is detected, ECU
  recognizes it as working rapidly acceleration
  pedal. And it is cause of rich injection control
  as adding fuel correction when acceleration

lt Rich injection control by fuel correction when
acceleration gt
lt Amplification of noise signal ECU doesnt
recognize idle state gt
39
TPS-6

• Explanation The noise is not occurred after
  separating TPS signal line from TCU connecting.
  But if it is TPS signal line which must be used
  with TCU connecting, noise may be reduced as
  separating TCU from connecting part as far as
  possible.
•  
• Enlargement of application If noise is occurred
  in TPS signal, find what is connected with TPS
  signal and ground line. And check noise after
  separating it. If noise is reduced, remove
  connecting part. But if removal is impossible,
  find point that the lowest noise is detected as
  moving connecting part. Nevertheless, if noise is
  not decreased, find point that the lowest noise
  is detected as moving ground line and connect it.
  It may be implemented by shield line.

40
TPS-7

• lt Example 2 gt Micro cut-off occurrence 
• Vehicle Accent 1.3 1.5L SOHC (Siemens
  system), Odometer Dont care 
• Problem description Sometimes engine is rough
  idle state. The floating is occurred without idle
  recovery and surging is taken place when
  acceleration. TPS value that is measured from
  scanner is normal but TPS value is very small in
  idle state.
• NOTICE Absolutely TPS value in idle state gtgtgt
  Adapted TPS value in idle state  
• Cause TPS signal is cut for very short time(
  ?40 120usec ). ECU regard it as TPS value (Below
  0.05volt) that is measured with micro cut-off
  phenomenon in idle state(If the idle TPS value
  which is memorized in ECU is less than normal
  one, it is set to idle TPS value). After that if
  it is again returned normal, ECU recognize it as
  working acceleration pedal and also dont apply
  idle correction.

41
TPS-8
Signal measurement

• Explanation Finally, ECU doesnt detect idle
  in spite of real idle state. So, it led to rough
  idle. The current vehicle (Production after
  Jun.1996 model year) have no problem with micro
  cut-off (Duration is less than 0.8) because ECU
  change TPS value after elapsed 0.8 sec in case
  that current TPS value is less than memorized
  one.
• Enlargement of application If engine is rough
  idle, first compare absolutely TPS value with
  TPS adaptation value from scanner in idle
  state. If these two values have difference more
  than 1.2 ?TPS, ECU doesnt detect idle in spite
  of real idle state. So, you must find root cause
  after inspecting why this phenomenon is happened.
  
• Example Micro cut-off / Bad return of
  acceleration cable / Bad connection of ground
  line.

42
TPS-9

• lt Example 3 gt The bad connection of TPS ground
  line
• Vehicle Rio 1.5L DOHC, Odometer 3,200Km 
• Problem description Sometimes engine is rough
  idle state. The floating is occurred without idle
  recovery and severe RPM cycling is taken place
  with electric load or A/C ON.  
• Cause If engine becomes so hot, TPS signal is
  unstable in idle state by bad connection around
  fuse box. So, ECU doesnt recognize idle state
  because the unstable signal is higher than TPS
  adaptation value in idle. It results in rough
  idle.

Signal measurement
43
TPS-10

• Explanation If RPM is unstable, the system
  which recognize idle by TPS signal(Without idle
  switch type) should check whether ECU recognize
  idle or not.
• Enlargement of application If engine is rough
  idle, first compare absolutely TPS value with
  TPS adaptation value from scanner in idle
  state. If these two values have difference more
  than 1.2 ?TPS, ECU doesnt detect idle in spite
  of real idle state. So, you must find root cause
  after inspecting why this phenomenon is happened.
  
• Example Micro cut-off / Bad return of
  acceleration cable / bad connection of TPS ground
  line.

44
AIR FLOW SENSOR-1 CHECK METHOD

• 1. With connecting the oscilloscope.
• 2. Check what the signal voltage is as stepping
  on and off the accelerator pedal in idle state.

NOTICE To measure the signal, ground line
should be earth to chassis or engine.
45
AIR FLOW SENSOR-2

• 1. Find and connect the Signal and Ground line
  referencing the wiring diagram.
• 2. After measuring the signal, compare the
  measured signal with Normal signal.
• (1) After checking in IDLE state, Measuring the
  signal at WOT (Whole Open Throttle) as stepping
  on the accelerator pedal
• (2) It prefers to check the TPS (Throttle
  Position Sensor) in the same time if possible.
• 3. Check the followings with connecting the
  scanner after making the engine fully warmed-up
  and keeping Idling above 10 minutes.
• lt Checking itemsgt
• (1)  Check that the additive adaptation value
  (fuel adaptation in IDLE) is in normal range
  (within 0.8 msec).
• (2)  Check whether the mass air flow value is
  changed as stepping on the accelerator pedal.
• (3)  Check that the multiplicative adaptation
  is in normal range (within 15) after driving
  (over 3 days)

46
AIR FLOW SENSOR-3 WAVE ANALYSIS

• MAP sensor
• The output voltage of MAP sensor according to the
  pressure of surge tank is as follows.

47
AIR FLOW SENSOR-4

• Hot film / Hot wire type mass air flow sensor
• The output voltage of MAF sensor according to
  the mass air flow(Kg/Hr) is as follows.

48
AIR FLOW SENSOR-5

• Karman vortex type
• The output pulse is different from mass air flow.

49
AIR FLOW SENSOR-6 FIELD EXAMPLE

• lt Example 1 gt In case of misfire occurrence from
  engine
• Vehicle MAP sensor equipped vehicle (SOHC
  engine is more severe gt Misfire is often
  occurred with a little bit lean fuel control) 
• Problem description The unstable RPM
  cycling(recovery after fast drop of RPM) and
  engine vibration are occurred in idle state. At
  the moment MAP sensor signal show spike
  phenomenon (Fast jump and drop of MAP sensor
  signal).
• Cause Misfire was occurred inside combustion
  chamber due to instantaneous lean fuel
  control(SOHC is over A/F 15.3 and DOHC is over
  A/F 15.7) with lean fuel correction(ECU decrease
  injection time because O2 sensor voltage is over
  0.5 volt) of O2 sensor feedback

Signal measurement
50
AIR FLOW SENSOR-7

• Explanation If misfire is occurred from engine,
  piston speed is rapidly reduced. At the moment
  the mass air flow is rapidly decreased from surge
  tank and pressure inside surge tank is rapidly
  increased. So, MAP sensor signal is increased as
  jumping.
• Enlargement of application The pressure
  variation inside surge tank is related to piston
  speed. Without fuel supply, pressure inside surge
  tank is inverse proportion to piston speed.
  Indeed, if piston speed is fast pressure is low,
  if it is slow pressure is high. So, you can guess
  compression ratio through the fact.
• If pressure inside surge tank is high when dry
  cranking(Cranking without fuel supply), piston
  speed is low and also it mean that compression
  ratio is high. In the contrary, if pressure
  inside surge tank is low, piston speed is high
  and also it mean that compression ration is low.
  Therefore The compression ratio can be relatively
  compared by surge tank pressure from dry
  cranking.

51
AIR FLOW SENSOR-8

• lt Example 2 gt In case of pulsation detection
• Vehicle MAF(Mass Air Flow equipped vehicle)
• Problem description If acceleration pedal is
  worked over 50 around 1300 1800 RPM, MAF
  sensor read abruptly a lot of mass air flow
  value. According to vehicle, engine may be no
  problem with the phenomenon but some vehicle may
  have surging and fuel smell from exhaust gas due
  to over injection time. Cause The pulsation is
  detected in intake air line. It is due to
  vibration(the front and rear direction) of air
  around sensing part. At the moment, if ECU detect
  pulsation engine is no problem but if not ECU
  inject fuel as lots MAF value. It led to rich
  fuel control.

Signal measurement
52
AIR FLOW SENSOR-9

• Explanation The vehicle which is equipped MAF
  sensor dont calculate injection time in
  pulsation area and use MAF value that is set by
  test with TPS RPM. But some vehicles dont make
  input value because it may not be exact.
• The MAF sensor pulsation value has big deviation
  according to car maker and especially in case of
  B maker, MAF sensor voltage is measured about 4.6
  volt when pulsation detection.
• Enlargement of application Even though a lot of
  MAF signal is detected, if engine is no problem,
  it may be ignored. Engine is no problem if ECU
  normally control it even wrong MAF signal. This
  case is example for it.

53
AIR FLOW SENSOR-10

• lt Example 3 gt The trouble check of MAP sensor
  signal
• Vehicle New sephia / Avella 1.3L / Pride
• Problem description Engine is stopped soon
  after starting. The MAP signal is not measured.
  The MAP sensor signal line is broken but the
  scanner detects that MAP sensor is normal.
• Cause ECU didnt detect malfunction of MAP
  sensor. For detecting malfunction of MAP sensor,
  MAP signal should be remained over 30sec less
  than 0.1 volt. But engine was stopped soon
  (less than 30sec) after starting and it didnt
  satisfy malfunction detection condition.  
• Signal measurement Omission (Constant 0.07
  volt )

54
AIR FLOW SENSOR-11

• Explanation

Above chart describe that ECU detect malfunction
after elapsed 8 sec but above problem vehicles
detect malfunction after elapsed 30sec.
Therefore ECU detect malfunction after elapsed
30sec with KEY ON. Enlargement of
application The scanner can detect it that ECU
must recognize malfunction. Therefore if ECU
dont detect malfunction, error will not be
visible through scanner. If scanner dont detect
malfunction in spite of engine problem, it should
be repaired.
55
AIR FLOW SENSOR-12

• lt Example 4 gt The problem when exhaust gas
  pressure is increased
• Vehicle Prince 2.0L SOHC, Odometer about
  128,000Km
• Problem description The vehicle which is
  equipped with MAP sensor was not accelerated with
  lack of power and stalled on heavy rain day.
  After that engine is hard to start and O2 sensor
  recognize rich fuel control. But any error is not
  detected in scanner.
• Assumption
• O2 sensor recognize rich fuel control(signal is
  close to 1volt) Through this phenomenon, we
  can guess factors that control toward rich
  direction. It is guessed over EMS system.
• 1) High pressure of fuel pump
• 2) Abnormal O2 sensor signal. In case of becoming
  damp in connecting part, it may result in short
  to battery and it may lead to rich side injection
  control(O2 sensor signal is over 1 volt)
• 3) A lot of fuel vapor gas comes from canister
  solenoid valve
• 4) The fuel adaptation value is too high with
  positive value. It lead to rich fuel control
  before O2 sensor feedback.
• 5) A lot of oil gas comes from PCV valve.
• 6) The injection is increased by abnormally high
  MAF value.
• 7)The injection time correction is a lot due to
  limp home by coolant temperature sensor
  trouble(Limp home mode Called Safe mode and
  it is replace value when malfunction)
• 8) The injection time is calculated too much due
  to limp home by air temperature sensor trouble.
• 9) The injection is controlled with rich
  correction due to lack of mass air flow. The lack
  of MAF is due to insufficient intake valve
  opening by hydro tappet malfunction.

56
AIR FLOW SENSOR-13

• In 1) case, if pressure of fuel pump is high,
  injection time will be controlled toward rich
  direction. Why power is lack and poor
  acceleration is happened during driving? You will
  not be able to answer about this problem if you
  dont have experience that check it as changing
  fuel pressure. But you can think that over
  injection time control make lack of power.
• For your reference, LBT(Leanest Fuel Best Torque)
  is injection time which is determined for best
  power torque withoutnO2 sensor feedback.

• In conclusion for 1), the answer is no. Because
  torque power is not decreased dramatically by
  over injection time control as described above
  charts. Actually you can feel lack of power
  little bit with 20 injection time increment but
  dont decrease dramatically.

57
AIR FLOW SENSOR-14

• If it is 2)case, ECU will reduce injection
  correction as recognizing rich control. In the
  case, power may be actually lack due to
  insufficient fuel and it can be occurred with
  O2sensor feedback. So, the phenomena is unrelated
  to engine start because start or post start
  injection time is controlled without feedback by
  set value in ECU.
• If it is 3), how to be controlled engine?
• The overflow of vapor gas is determined by vapor
  pressure in fuel tank. If canister solenoid valve
  has leakage when engine start with hot ambient
  condition or idle sate, engine is roughly started
  and engine stall may be occurred in idle sate.
  But due to that, dont feel lack of power and
  also driving about 10 min reduces overflow of
  vapor gas.
• In 4) case, it is disappeared with feedback
  control. Therefore this is not major cause.

58
AIR FLOW SENSOR-15

• In 5) case, power will not be decreased by
  overflow of oil gas. Of course, if vapor gas is
  not supplied constantly to individual cylinder,
  engine vibration is occurred and engine sound is
  rough due to A/F difference each cylinder. At the
  moment, O2 sensor signal is unstable but engine
  is not hard to start.

In 6) case, injection time will be rich before
O2 sensor feedback but it is reduced by injection
time correction. So, it is not the root cause.
Especially injection time is determined by
cranking conditions (Coolant temperature, RPM
when cranking, Cranking time) without relation
MAF value.
59
AIR FLOW SENSOR-16

• If it is 7) case, measure air temperature
  sensor. And if TIA is less than 20 ?C, set to
  current TIA and if TIA is higher than 20 ?C,
  set to 20 ?C coolant temperature . If
  malfunction of coolant temperature sensor is
  detected, cooling fan is always ON and engine is
  hard to start due to limp home(ECU recognize
  80?C as 20?C.)

• If poor acceleration is occurred when first
  driving right after engine start and it come back
  normal state after elapsed some time, it would be
  root cause of problem but it is not because power
  is not increased after elapsed some time. ECU
  must detect malfunction for limp home. But it is
  not the cause because any error is not detected.

60
AIR FLOW SENSOR-17

• In 8) case, same as 7) case. ECU recognize 20
  ?C if malfunction is detected.
• ltReferencegt In latest algorithm, ECU recognize
  TIA as 55?C in case that coolant temperature
  is less than 10?C.
• Finally, in 9) case, rich fuel control is
  disappeared with feedback and power is decreased
  due to lack of mass air flow. But is it
  impossible to start engine due to insufficient
  oil supply? Of course it depends on oil quantity
  in tappet but you will have experience that
  engine is hard to start after assembling tappet.
  This may be very approached to conclusion because
  power is decreased and engine is not started with
  more severe case.
• But we have to find key point.
• In case of insufficient opening of tappet, O2
  sensor signal is unstable. And it is due to A/F
  difference of each cylinder by inconstant air
  supply into individual cylinder. Please refer to
  picture for 5)
• Cause The problem was solved from unexpected
  phenomena.
• It is due to blocking of exhaust pipe (Blocking
  of exhaust pipe gt Increase of exhaust resistance
  gt a lot of residual gas generation gt Increase
  MAP value gt Over injection time gt Rich fuel
  control gt Lack of power during driving).

61
OXYGEN SENSOR-1 CHECK METHOD

• Oxygen sensor signal voltage (between 0 to
  5volt) can be going well to be heated by exhaust
  gas (over370degC) though Oxygen sensor has
  heater. And you can diagnose the function of
  oxygen sensor exactly to be feedback. Check the
  troubles as following procedure.1. Keep on
  stepping on the accelerator pedal lasting the
  engine revolution over 2000rpm during 2 minutes.
• 2. Make the Oxygen sensor feedback If heater was
  not installed, Feedback condition is difficult at
  vehicle stop. Thus must drive over 5 minutes in
  speed over 60Km/H generally.
• lt NOTICE gt After making the feedback, signal
  must be checked on condition of engine running
  not key off.
• 3. Measure the Oxygen sensor signal with
  connecting the HI-Scan or Oscilloscope.
• lt NOTICE gt It prefers not to use Multi-meter
  because it is difficult to show the fast signal
  changing.
• lt NOTICE gt In case of connecting the Auto
  Scanner, there is no need additional trouble
  checking because It analyses and diagnoses the
  troubles automatically.

62
OXYGEN SENSOR-2

• 1.   Find and connect the signal and ground line
  with referencing the wiring diagram.
• 2.   After measuring the signal, compare the
  measured signal with Normal signal.
• (1) Check whether the signal switches (up and
  down) too fast (within 0.1 second) or slow
  (over 5 second)
• (2) It prefers to use the Scanner in the same
  time.
• 3. Check the followings with connecting the
  scanner after making the engine fully warmed-up
  and keeping Idling above 10 minutes.
• lt Checking itemsgt
• (1) check that the additive adaptation value
  (fuel adaptation in IDLE) is in normal range(
  within 0.8 mmsec)
• (2) check that the multiplicative adaptation is
  in normal range(within 15) after driving( over
  3 days)

63
OXYGEN SENSOR-3 WAVE ANALYSIS

• Explanation is for zirconium O2 sensor. In case
  of Titanium O2 sensor, the voltage range is 05V
  and signal is opposition.
• When oxygen sensor signal is measured, the output
  voltage depends on exhaust gas temperature even
  though heater is existed. That is, the higher
  exhaust gas temperature is the higher oxygen
  sensor output voltage. So O2 sensor signal check
  should be done after acceleration. And if signal
  is moving(up/down), the sensor status is
  considering as normal and then its required the
  analysis of fuel delivery system of combustion
  chamber.

The output voltage of oxygen sensor is as follows.
ltOxygen sensor signal voltage Zirconium(left),
Titanium(right) gt
64
OXYGEN SENSOR-4
 

• lt Too rich fuel (left) / Too lean fuel(right) gt  

If cylinder fuel distribution is bad, the signal
shape is unstable(fast switching). It means
sensor is normal but fuel system is somewhere
wrong.
lt In case fuel distribution is not goodgt
65
OXYGEN SENSOR-5 FIELD EXAMPLE

• lt Example 1 gt The problem occurrence when start
  feedback before O2 sensor light-off
• Vehicles New sephia 1.5L SOHC/DOHC, Odometer
  More than 28,000Km Prince 2.0L SOHC, Odometer
  67,000Km Espero 2.0L SOHC/DOHC, Odometer
  82,000Km. 
• Problem description The acceleration is poor
  and RPM cycling is occurred in idle state. Engine
  stall is happened when working rapidly
  acceleration pedal with RPM cycling and if
  acceleration pedal is slowly worked, RPM is
  slowly increased and color of exhaust gas is
  black.  
• Cause In case of non-heated O2 sensor type, ECU
  control fuel injection as starting feedback
  through O2 sensor before O2 sensor light-off. At
  the moment, O2 sensor signal stay from 0.40 to
  0.47 volt because it is not reached light-off
  temperature, so ECU recognize lean fuel control
  and add injection time. It lead to too rich fuel
  control(A/F 6 9) problem.

66
OXYGEN SENSOR-6
Signal measurement

• Explanation This is happened by low exhaust gas
  temperature. Most of conventional vehicle,
  exhaust gas temperature is within from 280 to
  340? range in idle state. Therefore it is due to
  low exhaust gas temperature (Minimum temperature
  for O2 sensor light-off 370?).  
• Enlargement of application Even though this
  problem is not occurred with heated O2 sensor
  type, after replacing it, O2 sensor signal
  ground line make originally connection with ECU
  and heater line connect with after main relay.
  After that replace new spark plug.
• Reference Fuel wetting of spark plug result in
  low ignition performance.

67
OXYGEN SENSOR-7

• lt Example 2 gt The problem occurrence due to
  abnormal O2 sensor signal
• Vehicles Avante 1.5L DOHC, Odometer About
  28,000Km
• Problem description Engine stall is occurred
  after severe RPM cycling as soon as engine
  start.(As soon as O2 sensor feedback start). At
  the moment, O2 sensor signal voltage stay 1.0
  1.2 volt.

Cause O2 sensor signal line is short to battery
due to moisture between connecting parts. Due to
that, signal voltage is high and ECU reduce fuel
injection(Max33 or 50) as starting feedback.
Finally engine stall was occurred with lack of
fuel.
Signal measurement
68
OXYGEN SENSOR-8

• Explanation ECU detect malfunction of O2 sensor
  with signal voltage higher than 1.3 volt.
  Therefore this case is due to feedback without
  error detection.
• Enlargement of application Fuel control status
  that is supplied into engine is observed by O2
  sensor signal measuring but fuel injection time
  adding(higher than 0.5volt) or deduction(less
  than 0.5volt) is only observed. In this case,
  although O2 sensor signal is high due to short to
  battery, we cannot distinguish whether actual
  fuel injection is much or less. But you have to
  expect that ECU reduce fuel injection with O2
  sensor feedback.

69
OXYGEN SENSOR-9

• lt Example 3 gt Fuel injection status check through
  O2 sensor
• Vehicles Rio 1.5L DOHC, Odometer 4,200Km
• Problem description O2 sensor signal is rapidly
  switched and engine vibration is occurred. Due to
  knocking detection, performance and fuel economy
  is poor.  
• Cause The intake valve closing and opening was
  not exact due to number 3 cylinder hydro tappet
  trouble. It result in lack of mass air flow in
  corresponding cylinder and A/F of 3 cylinder is
  rich

Signal measurement
70
OXYGEN SENSOR-10

• Explanation A/F between each cylinders is
  different(3 cylinder is rich), so engine
  vibration is occurred and ignition is retarded
  with knocking detection. It leads to bad
  performance and fuel economy. 
• Enlargement of application Fuel control status
  that is supplied into engine is observed by O2
  sensor signal measuring. Thus you can estimate
  that fuel injection time is lack(higher than
  0.5volt) or over(less than 0.5volt). With rapidly
  O2 sensor signal switching, you can estimate
  fuel status that is supplied into combustion
  chamber (Ex Misfire in combustion chamber, A/F
  difference between cylinders injector clogging,
  fuel gas overflow from purge valve).

71
INJECTOR-1 CHECK METHOD

• 1. Oscilloscope
• 2. Wiring diagram of injector.
• lt Reference gt
• It prefers not to use Multi-meter because it is
  difficult for the Multi-meter to display the fast
  signal changing.
• 1.   Find and connect the signal and ground line
  with referencing the wiring diagram.
• 2.   After measuring the signal, compare the
  measured signal with Normal signal.
• (1)    Is the injector opening point different
  at each cylinder?.
• (2)    Is the injector opening point different
  at each cycle?.
• (3) Is the injector opening voltage normal at
  each cylinder?
• 3. It prefers to check the following signals at
  the same time to check the normal operating state
  of injector exactly.
• lt Checking itemsgt
• (1) Crank angle sensor signal Opening point.
• (2) Oxygen sensor signal Is the oxygen sensor
  signal switching (Up and down) frequency
  constant, too fast switching and noising of
  oxygen sensor signal there is some injector
  defect (opening defect, injector clog)

72
INJECTOR-2
73
INJECTOR-3 WAVE ANALYSIS

• Output voltage when injector is operating.

74
INJECTOR-4

• Injector signal with crank angle position signal .

75
INJECTOR-5 FIELD EXAMPLE

• lt Example 1 gt
• Vehicle Tiburon 2.0L DOHC, Odometer 78,000Km
• Problem description RPM increase is too slow
  when acceleration and surging is occurred during
  driving. O2 sensor signal is very unstable.
• Cause O-ring is torn when insert injector. And
  fuel line has leakage from the point. It results
  in inconsistent fuel supply into combustion
  chamber.

Signal measurement
76
INJECTOR-6

• Explanation In case of malfunction of injector
  itself(Clogging, Trouble of internal coil),
  injector signal is similar to normal. Therefore
  it is so difficult to find malfunction of
  injector with injector signal and the problem
  should be solved with A/F of individual cylinder
  from O2 sensor.
• Enlargement of application When O2 sensor
  signal is unstable, you should expect that A/F is
  different between cylinders and find the root
  cause.
• Reference Cause type
• (1)     The overflow of fuel gas from PCV or
  purge valve
• (2)     Insufficient fuel supply from a certain
  injector
• (3) The lack of mass air flow from a certain
  cylinder (Abnormal closing and opening of intake
  valve)

77
INJECTOR-7

• Vehicles Avella / New sephia / Pride
• Problem description Engine is started with
  hesitation. Engine is stopped soon after started
  in cold ambient condition and restart is hard.
• Cause Power, which is supplied, to distributor
  is cut during very short time when key is
  released after engine start. This phenomenon
  cause abnormal crank angle signal and it result
  in engine problem. Injector signal is
  intermittently missed.

Signal measurement
78
INJECTOR-8

• Explanation When key is released after engine
  start, ECU stop fuel injection from long tooth
  detection as soon as missing crank angle signal
  by the bouncing phenomenon(Repeat contact and
  non-contact) and start again injection after
  normal long tooth signal is detected..
• Enlargement of application
• In case of fuel injection stop or abnormal
  ignition timing, ECU doesnt acquire normal crank
  angle signal, so crank angle sensor signal should
  be checked whether it is normal or not. And
  ignition timing and fuel injection control should
  be checked at the same time.
• The cause of these cases is guessed as followings
• A.  In case of back-fire of LPG vehicle
• B.  In case that engine stall is suddenly
  occurred in idle sate
• C.  In case that engine vibration is
  intermittently occurred
• D. In case that engine is started with
  hesitating as jamming flywheel in self motor

79
IGNITION-1 CHECK METHOD

• 1. Oscilloscope (2nd Order signal measuring
  instrument)
• 2. Wiring diagram for ignition.
• lt NOTICEgt
• It prefers not to use Multimeter because it is
  difficult to display the fast changing signal.
• 1.   Find and connect the signal and ground line
  with referencing the wiring diagram.
• 2.   After measuring the signal, compare the
  measured signal with Normal signal.
• (1)    Dwell time / ignition timing at each
  Coil.
• (2)    Signal wave showed at each coil. (2nd
  order wave if possible)
• 3. It prefers to check the following signals at
  the same time to check the normal operating state
  of injector exactly.
• lt Checking items gt
• (1) Cam and Crank angle signal check the
  abnormal ignition timing.
• (2) Oxygen sensor signal Is the oxygen sensor
  signal switching (Up and down) frequency
  constant, too fast switching and noising of
  oxygen sensor signal phenomenon by Misfire.

80
IGNITION-2
81
IGNITION-3 Wave Analysis

• Voltage shape during ignition is as shown below

82
IGNITION-4

• Ignition Primary signal check
• Ignition secondary wave shows discharging status
  according to the status of the cylinder.
• As it has a complex relation with status of
  components and wires which control electrical
  energy at first coil, status of second coil which
  is induced by high voltage and status of mixed
  gas in the cylinders representing how much
  thermal electrons discharge while being
  discharged finally, To confirm whether status of
  supplying electrical energy to ignition system is
  good or not, it is desirable to check the current
  from first coil at each cylinder.
• To generate enough ignition energy at secondary
  voltage, there must be enough current at first
  coil. Although this current is different
  according to the sorts of the vehicle, generally
  60.5A is considered as a standard.
• The point keeping in mind is despite this
  current is weak, ignition secondary wave may not
  have any problem.
• If air-fuel ratio in the normal temperature (over
  20 C) is closer to stoichiometric , Ignition by
  secondary voltage is possible with approximately
  1/2001/1000 energy of the ignition energy in the
  cold temperature (below -5C).
• In case that the current flows weak , but
  ignition secondary wave has no problem,
• Ignition secondary wave must be confirmed whether
  it is normal state at rapid acceleration, cold
  temperature, both rich and lean of fuel
  condition.
• Ignition energy at normal temperature and
  stoichiometric condition 12mJ
• Cold temperature and Rich fuel approximately 1J

83
IGNITION-5

• 1) Distributor Less Ignition type

lt Measuring partgt Measure flowing time and the
current at checkpoint 1,2 ltCheckpointgt
Resistance of wire, status of components
(checking components 1 internal ECU or
external TR)
84
IGNITION-6

• 2) Distributor Ignition type

ltMeasuring partgt Measure flowing time and the
current at checkpoint 1,2 ltCheckpointgt
Resistance of wire or a short, status of
components (checking components 1 internal
ECU or External TR, checking components 2
ignition coil)
85
IGNITION-7

• Most important point is dwell time(depends on
  battery voltage). If battery voltage is 13.5V
  the dwell time is 3.03.5msec. Cylinder by
  cylinder deviation(over 20) check is required to
  know the normal or not. If the deviation is more
  than 20, it means coil, power TR or wire has a
  problem..
• Also check the ECU recognized battery voltage is
  stable(within 3V). Because the dwell time can be
  some difference depends on battery voltage.

86
IGNITION-8
87
IGNITION-9

• Ignition Primary signal check
• Ignition secondary wave means discharging to high
  voltage from electric energy at first coil.
  Especially ignition system in automobile,
  discharging time discharging voltage level is
  affected more by status of the mixed gas in the
  cylinders and plug than electric energy from
  first coil.
• When secondary high voltage (approximately
  2000030000V) is induced instantly and flows, the
  flow means discharging, time is discharging time,
  Voltage is discharging voltage.
• When the secondary voltage generates, this energy
  separates carbon and hydrogen from constituent of
  fuel.
• While this constituent of fuel separates,
  electrons are generated. Its called
  thermal-electron.
• Discharging voltage combusted normally from the
  cylinder is a voltage discharging through those
  thermal-electrons.
• Since level and time of the discharging voltage
  are affected by the temperature and shape
  (vortex) in the cylinder, air-fuel ratio of the
  mixture, and compression ratio, it is hard to fix
  absolute value. So it must be analyzed through
  comparing each cylinder.

88
IGNITION-10

• ltIgnition secondary wave classification of each
  wavegt

ltIgnition secondary wave analysis graph of each
wavegt
89
IGNITION-11

• Parts to confirm ignition secondary wave are as
  follows. 
• 1) Distributorless type 
• ltMeasuring partsgt
• Measure flowing time and the current at
  checkpoint 1,2 
• ltCheckpointgt
• Resistance of wire, status of components
• 2) Distributor Ignition type
• ltMeasuring partgt
• Measure voltage secondary wave at checkpoint
  1,2(plug wire at each cylinder) 
• ltCheckpointgt
• Resistance of wire or short, status of
  components (checking components 1,2)

90
IGNITION-12
91
IGNITION-13

• Comparing each cylinder
• (1) After a current flowed, if peak (voltage of
  surge) is low or discharging time is short and
  high This means that electric energy through
  discharged thermal-electron isnt discharging
  well, while molecule separates from fuel.
• Electric energy trying to ignite isnt for fuel
  combustion , its kind of discharging
  phenomenon through plug ejja. So misfire occurs
  in the cylinder.
• Confirm the status of plug (attached carbon,
  clearance)When a peak voltage is generated, some
  parts of voltages flow on the attached carbon in
  the plug tip. So it gets weak to separate
  molecule.
• In case that discharging voltage flows through
  carbon to plug ejja.
• b. Check plug wiring and status of coil
• In case that connection to plug and high voltage
  wire and coil status arent good , peak voltage
  becomes weak.
• Then electric energy to separate fuel molecule
  becomes weak because Thermal-electrons generated
  from fuel are little so that resistance
  discharges large state..
• c. Check if the mixture ratio of fuel is too
  lean
• In case that fuel is lean, even more electric
  energy is needed to generate thermal-Electrons
  separated from fuel molecule, Thus peak voltage
  generated near stoichiometric with normal fuel
  isnt enough to generate thermal-electron so that
  resistance discharge large state

92
IGNITION-14

• d. Check if the compression ratio is too high
• In case compression is high, far more electric
  energy is needed to generate thermal-electrons
  separated from fuel molecules.
• Thus peak voltage generated near normal
  compression ratio isnt enough to generate
  thermal-electron so that resistance discharges
  large state. -- It isnt for normal case.
• its for especially reorganized vehicle. Just
  do interpret that as theoretical aspect.
• ltReferencegt
• More detail refers to chap 6. 6.3 uniform
  ignition energy to each cylinder

93
IGNITION-15

• (2)After a current flowed, if a peak(voltage of
  surge) is low and discharging time is long
• Although electric discharge is well, it causes
  power reduction because discharging electric
  energy (spark) gets weak and long so that
  combustion timing of fuel gets long and flame
  spread leading to combust between fuel particles
  gets weak
• a. Check status of plug (clearance of tip is too
  small)
• b.  Check compression pressure of cylinder is low
• c.  Check the mixture ratio is too rich
• ltReferencegt
• More detail refers to chap 6.6.3 uniform
  ignition energy to each cylinder.

94
IGNITION-16
95
IGNITION-17
96
IGNITION-18 FIELD EXAMPLE

• lt Example 1 gt
• Vehicles Tiburon 2.0L DOHC, Odometer 42,000Km
• Problem description The vehicle which platinum
  plug is equipped has poor performance when
  acceleration, black color of exhaust gas and
  engine is hard to start in cold ambient
  condition.
• Cause There was no problem in platinum spark
  plug but plug that is used in high temperature
  condition(For racing car) was equipped. Therefore
  it led to insufficient secondary ignition fire
  with too low tip temperature.
• Signal measurement In case of using all of
  platinum spark plug, secondary ignition signal is
  normal. But it has big difference after replacing
  original plug(Heat value No.7).

97
IGNITION-19
98
IGNITION-20

• Explanation (Analogical interpretation) The
  resistance is low because tip is not heated
  easily with platinum plug of cooling type. So,
  peak voltage is circulated into plug tip before
  discharging heat electron from fuel and discharge
  voltage is a little bit high because resistance
  of tip is bigger than discharging through a
  electron from fuel.
• Enlargement of application If the discharge
  voltage is high with short duration, it is not
  discharged by heat electron that is discharged
  from fuel. It is discharged into other part and
  lead to insufficient ignition fire. 
• A. The carbon accumulation of plug tip
• B. Too lean fuel control
• C. Ignition coil line is open circuit or peak
  voltage is low due to bad ignition coil
• D. The gap of plug tip is too wide
• E. Insufficient secondary voltage due to bad
  ignition coil

99
IGNITION-21

• lt Example 2 gt
• Vehicle Scoupe alpha 1.5L Turbo, Odometer
  128,000Km  
• Problem description Engine is stopped with
  starting and restart is hard. After elapsed long
  time, engine is started but stopped soon.
• Cause The spark plug has no resistance. After
  discharging as using it, big noise is happened
  and influence to ECU. It makes a mistake in ECU. 
• Signal measurement After discharging,
  oscillation of ignition signal is big and long
  comparing to normal. It has big difference
  comparing to plug of other cylinder

100
IGNITION-22
101
IGNITION-23

• Explanation The secondary ignition is factor to
  generate the biggest noise in vehicle. This
  example prevents normal operation of ECU. But it
  also may make noise into other component and
  actuator for electronic control.
• Enlargement of application If you accumulate
  many experiences for discharging voltage signal,
  you can get criteria for normal ignition signal.
  If ignition signal has big difference comparing
  to normal. find normal discharging voltage signal
  as changing factor with the experience.
• A.  Spark plug (For racing car, Heat value, To
  be resistance or not, Gap, Carbon accumulation
  Etc.)
• B.  Wiring for high tension voltage of ignition
  system
• C.  Parts of ignition system (Coil, Power TR
  Etc.)
• D.  Injector (Flow for tuning, Spray angle,
  number of injector nozzle Etc)
• E.  Abnormal fuel (Overflow of fuel gas through
  PCV or purge valve) or overflow of EGR gas

102
IGNITION-24

• lt Example 3 gt
• Vehicle Avante 1.5L DOHC, Odometer 86,000Km 
• Problem description RPM is unstable in idle
  state after engine start. Engine vibration is
  also happened. The performance is lack when
  acceleration.
• Cause The carbon is accumulated on stem of
  intake valve. The intake valve is not closed
  completely with warmed up engine because valve
  stem is bigger and bigger with engine warm up. It
  results in low compression pressure. In case of
  using adding material to promote research octane
  number, carbon in element of fuel is accumulated
  on metal. 
• Signal measurement
• The secondary ignition signal of cylinder which
  is occurred the phenomena has long and low
  discharging voltage.

103
IGNITION-25
104
IGNITION-26

• Explanation Low compression pressure makes low
  discharging energy of secondary ignition signal.
  If discharging energy is low, energy that is
  conducted to secondary ignition coil is
  completely exhausted and need long time.
  Therefore discharging voltage is low and time is
  long.
•  
• Enlargement of application The low discharging
  voltage mean that resistance for discharging is
  low. It led to insufficient ignition fire and
  hard to ignite in mixed fuel gas.
• A.  Spark plug (The gap of plug is too narrow)
• B.  Moisture in combustion chamber
• C. Too low compression pressure

105
ISC VALVE-1 CHECK METHOD

• 1. Oscilloscope.
• 2. Wiring diagram of ISC valve.
•  
• lt Referencegt
• It prefers not to use Multi-meter because it is
  difficult for the Multi-meter to display the fast
  signal changing.
• 1.   Find and connect the signal and ground line
  with referencing the wiring diagram.
• 2.   After measuring the signal, compare the
  measured signal with Normal signal.
• (1)  As there is several power lines according
  to ISC valve type, Measure the signal at the same
  time.
• (2)  Lets reference that ISC valve power line
  is shorted by ECU though source of electricity is
  from Battery.