1. ECG ELECTRON COMBUSTION GRAPH FOLLOW THE BOUNCING ELECTRON
STEVE ZACK
STEVE ZACK

2. UNDERSTANDING THE PATTERN

3. 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

4. LAB SCOPE
PULSE WIDTH ON
PULSE
WIDTH
OFF OFF

5. LAB SCOPE
FREQUENCY (Hz) IS THE NUMBER OF TIMES SOMETHING OCCURS WITH IN ONE SECOND
MEASURED IN HERTZ (Hz)

6. LAB SCOPE
FREQUENCY
2 OCCURENCES EVERY SECOND EQUALS 2 Hz
MILLISECONDS

7. HOOKING UP THE SCOPE

8. LAB SCOPE TO TEST A SENSOR, BACK PROBE THE SENSOR SIGNAL RETURN WIRE
TO TEST AN ACTUATOR, BACK PROBE THE COMPUTER CONTROLLED GROUND

9. SENSOR - BACK PROBE SIGNAL RETURN
HALL EFFECT SWITCH

10. ACTUATOR (INJECTOR) - BACK PROBE COMPUTER CONTROLLED GROUND

11. 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

12. GROUND
CHASSIS GROUND
NOICE

13. PATTERN INTERPRETATION

14. PICK UP COIL VSS, WSS, DISTRIBUTER SENSOR SIGNAL RETURN - HI
SENSOR SIGNAL RETURN - LO

15. GOOD PATTERN
BAD PATTERN
WEAK PICKUP COIL
MISALIGNED POLE PIECE

16. SENSOR SIGNAL RETURN
TPS
CTS

17. GOOD PATTERN
BAD PATTERN
OPEN IN SENSOR RESISTOR
LOW RESISTANCE IN SENSOR
HIGH RESISTANCE IN SENSOR

18. SENSOR SIGNAL RETURN
HALL EFFECT SWITCH
DISTRIBUTER
CRANK SENSOR
MAF

19. GOOD PATTERN
BAD PATTERN
SIGNATURE PROFILE PIP #1 TDC
AS LOAD OR SPEED INCREASE, Hz INCREASE
TIME CHANGE WITHOUT LOAD CHANGE
OFF SIGNAL CRASH

20. BAD PATTERN
ON SIGNAL NOT STABLE
LOOSE GROUND WIRE
LOOSE VOLTAGE WIRE

21. COMPUTER CONTROLLED GROUND
INJECTOR
SOLENOID

22. GOOD PATTERN
BAD PATTERN
NARROW P.W. - LEAN WIDE P.W. - RICH
LOW FREQUENCY HIGH FREQUENCY LEAN RICH
LOOSE VOLTAGE WIRE

23. BAD PATTERN
LOOSE GROUND WIRE
WEAK SOLENOID COIL

24. CHARGING SYSTEM - ALTERNATOR DIODE
ALTERNATOR OUTPUT
TO BATTERY +
ALTERNATOR
CHARGING SYSTEM - ALTERNATOR DIODE

25. GOOD PATTERN
BAD PATTERN
BOUNCING BRUSH
POSITIVE DIODE SPIKE
NEGATIVE DIODE SPIKE
OPEN DIODE

26. BAD PATTERN
FLAT DIODE
POOR BRUSH CONTACT
EXCESS AC VOLTAGE

27. O2 SIGNAL RETURN
HO2S
HEGO
EGO
O2 SENSOR

28. GOOD O2 PATTERN
SECONDARY OR LEAN MISFIRE

29. TEST AT 2000 RPM ENGINE AT OPERATING TEMPERATURE
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

30. SINGLE SPARK PLUG WIRE TEST - POLARITY MAY NEED TO BE REVERSED TO INVERT PATTERN

31. 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

32. TURBULENCE, INTAKE VALVE, CARBON ON INTAKE VALVE, CARBON ON PLUG
GOOD - PATTERN
FOULED PLUG - CARBON
LOW COMPRESSION

33. EXHAUST VALVE
INTAKE VALVE, LEAN MISFIRE
FUEL FOWLING, RICH CONDITION - CONDENSING AT CYLINDER WALLS
FOULED PLUG - OIL, FUEL, CARBON

34. TROUBLE TREE CHART

35. 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

36. STEP A
PCM

37. 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

38. STEP B SENSOR

39. 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

40. STEP C
5 VOLT
REFERENCE
STEP C
SENSOR GROUND

41. TROUBLE TREE CHART STEP D: DIGITAL SENSOR THREE AREAS
A - VOLTAGE SUPPLY CIRCUIT
(PROBLEMS - REPAIR CIRCUIT)
B - SENSOR
(PROBLEMS - REPLACE SENSOR)
C - GROUND CIRCUIT

42. SUMMARY TROUBLE SHOOTING PROCEDURE
5 VOLT
“A”
“C”
0 VOLT