ECG ELECTRON COMBUSTION GRAPH FOLLOW THE BOUNCING ELECTRON

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ECGELECTRON COMBUSTION GRAPHFOLLOW THE
BOUNCING ELECTRON

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UNDERSTANDING THE PATTERN

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LAB SCOPE

• PULSE WIDTH (P.W.) IS THE TIME THE CIRCUIT IS ON,
  COMPLETING ITS PATH TO GROUND
• MEASURED IN MILLISECONDS (m.s.)
• MEASURED FROM THE BEGINNING OF ON TO THE END OF ON

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LAB SCOPE
PULSE WIDTH
ON

PULSE WIDTH
OFF
OFF
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LAB SCOPE

• FREQUENCY (Hz) IS THE NUMBER OF TIMES SOMETHING
  OCCURS WITH IN ONE SECOND
• MEASURED IN HERTZ (Hz)

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LAB SCOPE
FREQUENCY
2 OCCURENCES EVERY SECOND EQUALS 2 Hz

0 10 20 30 40 50 60 70 80 90
1 10 20 30 40 50 60 70 80 90
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MILLISECONDS
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HOOKING UP THE SCOPE

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LAB SCOPE

• TO TEST A SENSOR, BACK PROBE THE SENSOR SIGNAL
  RETURN WIRE
• TO TEST AN ACTUATOR, BACK PROBE THE COMPUTER
  CONTROLLED GROUND

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SENSOR - BACK PROBE SIGNAL RETURN
HALL EFFECT SWITCH
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ACTUATOR (INJECTOR) - BACK PROBE COMPUTER
CONTROLLED GROUND
INJECTOR
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LAB SCOPE

• NOISE IN A WAVE FORM CAN BE CAUSED BY AN OUTSIDE
  SOURCE OR MAGNETIC FIELD
• ALWAYS USE THE SCOPES CHASSIS GROUND AND HOOK IT
  TO THE ENGINE BLOCK
• KEEP THE SCOPE LEADS AWAY FROM ELECTRICAL DEVISES

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GROUND
CHASSIS GROUND
NOICE
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PATTERNINTERPRETATION

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SENSOR SIGNAL RETURN - HI
PICK UP COIL VSS, WSS, DISTRIBUTER
SENSOR SIGNAL RETURN - LO
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GOOD PATTERN BAD PATTERN BAD PATTERN
WEAK PICKUP COIL
MISALIGNED POLE PIECE
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SENSOR SIGNAL RETURN
TPS CTS
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GOOD PATTERN BAD PATTERN BAD PATTERN BAD
PATTERN
OPEN IN SENSOR RESISTOR
LOW RESISTANCE IN SENSOR
HIGH RESISTANCE IN SENSOR
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SENSOR SIGNAL RETURN
HALL EFFECT SWITCH DISTRIBUTER CRANK SENSOR MAF
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GOOD PATTERN GOOD PATTERN BAD PATTERN BAD
PATTERN
SIGNATURE PROFILE PIP 1 TDC
AS LOAD OR SPEED INCREASE, Hz INCREASE
TIME CHANGE WITHOUT LOAD CHANGE
OFF SIGNAL CRASH
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BAD PATTERN BAD PATTERN BAD PATTERN
ON SIGNAL NOT STABLE
LOOSE GROUND WIRE
LOOSE VOLTAGE WIRE
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COMPUTER CONTROLLED GROUND
INJECTOR SOLENOID
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GOOD PATTERN GOOD PATTERN GOOD PATTERN BAD
PATTERN
NARROW P.W. - LEAN WIDE P.W. - RICH
LOW FREQUENCY HIGH FREQUENCY
LEAN
RICH
LOOSE VOLTAGE WIRE
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BAD PATTERN BAD PATTERN
LOOSE GROUND WIRE
WEAK SOLENOID COIL
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ALTERNATOR OUTPUT
TO BATTERY
ALTERNATOR
CHARGING SYSTEM - ALTERNATOR DIODE
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GOOD PATTERN BAD PATTERN BAD PATTERN BAD
PATTERN BAD PATTERN
BOUNCING BRUSH
POSITIVE DIODE SPIKE
NEGATIVE DIODE SPIKE
OPEN DIODE
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BAD PATTERN BAD PATTERN BAD PATTERN
FLAT DIODE
POOR BRUSH CONTACT
EXCESS AC VOLTAGE
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O2 SIGNAL RETURN
HO2S HEGO EGO O2 SENSOR
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GOOD O2 PATTERN
SECONDARY OR LEAN MISFIRE
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O2 SENSOR TEST
LESS THAN 100ms
O2 SENSOR MUST SWITCH RICH TO LEAN AND LEAN TO
RICH IN LESS THAN 100ms FOR CATALYST TO
OPERATE TEST AT 2000 RPM ENGINE AT OPERATING
TEMPERATURE
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SINGLE SPARK PLUG WIRE TEST - POLARITY MAY NEED
TO BE REVERSED TO INVERT PATTERN
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PERCEPTION SCOPE - SECONDARY IGNITION TEST

• ENGINE HOT
• 1000 RPM
• SPECIFICATIONS
• BURN kV 1.1 kV TO 2.1 kV
• BURN TIME 1.0 ms TO 1.8 ms
• FIRING kV
• 7.5 kV TO 12 kV DISTRIBUTER
• 5 kV TO 12 kV DIS

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TURBULENCE, INTAKE VALVE, CARBON ON INTAKE VALVE,
CARBON ON PLUG
GOOD - PATTERN
FOULED PLUG - CARBON
LOW COMPRESSION
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EXHAUST VALVE
INTAKE VALVE, LEAN MISFIRE
FUEL FOWLING, RICH CONDITION - CONDENSING AT
CYLINDER WALLS
FOULED PLUG - OIL, FUEL, CARBON
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TROUBLE TREECHART

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TROUBLE TREE CHART

• STEP A
• TO TEST ALL CIRCUITS AND THE SENSOR.
• BACK PROBE SIGNAL RETURN AT THE PCM.
• NO PROBLEM - CIRCUIT OK
• YES PROBLEM - GO TO STEP B

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STEP A PCM
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TROUBLE TREE CHART

• STEP B
• TO TEST SENSOR, 5 VOLT AND GROUND CIRCUIT.
• BACK PROBE SIGNAL RETURN AT THE SENSOR.
• NO PROBLEM - REPAIR SIGNAL RETURN CIRCUIT
• YES PROBLEM -
• ANALOG SENSOR - GO TO STEP C
• DIGITAL SENSOR - GO TO STEP D

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STEP B SENSOR
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TROUBLE TREE CHART

• STEP C
• ANALOG SENSOR
• TO TEST 5 VOLT AND GROUND CIRCUIT.
• BACK PROBE 5 VOLT AND GROUND CIRCUIT.
• NO PROBLEM - REPLACE SENSOR
• YES PROBLEM - REPAIR 5 VOLT OR GROUND CIRCUIT

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STEP C 5 VOLT REFERENCE
STEP C SENSOR GROUND
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TROUBLE TREE CHART

• STEP D
• DIGITAL SENSOR
• THREE AREAS
• A - VOLTAGE SUPPLY CIRCUIT
• (PROBLEMS - REPAIR CIRCUIT)
• B - SENSOR
• (PROBLEMS - REPLACE SENSOR)
• C - GROUND CIRCUIT
• (PROBLEMS - REPAIR CIRCUIT)

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SUMMARYTROUBLE SHOOTING PROCEDURE
B
5 VOLT

A
C
0 VOLT