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ECG ELECTRON COMBUSTION GRAPH FOLLOW THE BOUNCING ELECTRON. UNDERSTANDING THE PATTERN. 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. LAB SCOPE. PULSE WIDTH. ON.
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ECGELECTRON COMBUSTION GRAPHFOLLOW THE BOUNCING ELECTRON STEVE ZACK
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
LAB SCOPE PULSE WIDTH ON PULSE WIDTH OFF OFF
LAB SCOPE • FREQUENCY (Hz) IS THE NUMBER OF TIMES SOMETHING OCCURS WITH IN ONE SECOND • MEASURED IN HERTZ (Hz)
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 2 MILLISECONDS
LAB SCOPE • TO TEST A SENSOR, BACK PROBE THE SENSOR SIGNAL RETURN WIRE • TO TEST AN ACTUATOR, BACK PROBE THE COMPUTER CONTROLLED GROUND
SENSOR - BACK PROBE SIGNAL RETURN HALL EFFECT SWITCH
ACTUATOR (INJECTOR) - BACK PROBE COMPUTER CONTROLLED GROUND INJECTOR
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
GROUND CHASSIS GROUND NOICE
SENSOR SIGNAL RETURN - HI PICK UP COIL VSS, WSS, DISTRIBUTER SENSOR SIGNAL RETURN - LO
GOOD PATTERN BAD PATTERN BAD PATTERN WEAK PICKUP COIL MISALIGNED POLE PIECE
SENSORSIGNALRETURN TPS CTS
GOOD PATTERN BAD PATTERN BAD PATTERN BAD PATTERN OPEN IN SENSOR RESISTOR LOW RESISTANCE IN SENSOR HIGH RESISTANCE IN SENSOR
SENSOR SIGNAL RETURN HALL EFFECT SWITCH DISTRIBUTER CRANK SENSOR MAF
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
BAD PATTERN BAD PATTERN BAD PATTERN ON SIGNAL NOT STABLE LOOSE GROUND WIRE LOOSE VOLTAGE WIRE
COMPUTERCONTROLLEDGROUND INJECTOR SOLENOID
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
BAD PATTERN BAD PATTERN LOOSE GROUND WIRE WEAK SOLENOID COIL
ALTERNATOR OUTPUT TO BATTERY + ALTERNATOR CHARGING SYSTEM - ALTERNATOR DIODE
GOOD PATTERN BAD PATTERN BAD PATTERN BAD PATTERN BAD PATTERN BOUNCING BRUSH POSITIVE DIODE SPIKE NEGATIVE DIODE SPIKE OPEN DIODE
BAD PATTERN BAD PATTERN BAD PATTERN FLAT DIODE POOR BRUSH CONTACT EXCESS AC VOLTAGE
O2 SIGNAL RETURN HO2S HEGO EGO O2 SENSOR
GOOD O2 PATTERN SECONDARY OR LEAN MISFIRE
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
SINGLE SPARK PLUG WIRE TEST - POLARITY MAY NEED TO BE REVERSED TO INVERT PATTERN
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
TURBULENCE, INTAKE VALVE, CARBON ON INTAKE VALVE, CARBON ON PLUG GOOD - PATTERN FOULED PLUG - CARBON LOW COMPRESSION
EXHAUST VALVE INTAKE VALVE, LEAN MISFIRE FUEL FOWLING, RICH CONDITION - CONDENSING AT CYLINDER WALLS FOULED PLUG - OIL, FUEL, CARBON
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
STEP A PCM
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
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
STEP C 5 VOLT REFERENCE STEP C SENSOR GROUND
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)
SUMMARYTROUBLE SHOOTING PROCEDURE “B” 5 VOLT “A” “C” 0 VOLT