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G006
SUBJECT: DIAGNOSTIC CHECKS & PROM CHANGES FOR 85-86 VIN CODE "F" AND 86
VIN CODE "8" V8 ENGINES
SYMPTOMS: SHUDDER AT LOW SPEEDS (LOCKUP TORQUE CONVERTOR SHUDDER)
SURGING OR HESITATION
ENGINE OVERSPEED IN FIRST GEAR ( MT )
POOR COLD DRIVABILITY
ROUGH IDLE
FALSE CODE 32,33,34,43,OR 44
IF ANY OF THE SYMPTOMS LISTED ABOVE PERSIST AFTER ALL NORMAL DIAGNOSTIC
CHECKS AND REPAIRS, GM HAS RELEASED REVISED PROMS WHICH MAY CORRECT OR
REDUCE THE PROBLEM. THESE PROMS ARE DESIGNED TO DO THE FOLLOWING:
RAISE TORQUE CONVERTOR LOCKUP SPEED TO REDUCE SHUDDER OR SURGING
REVISE FUEL CALIBRATION TO FURTHER REDUCE SURGING OR HESITATION
RAISE IDLE SPEED SLIGHTLY TO IMPROVE ROUGH IDLE
CORRECT ENGINE OVERSPEED IN FIRST GEAR
ELIMINATE FALSE CODES 32,33,34,43,AND 44
THE REVISED PROMS ARE MOST EFFECTIVE FOR CORRECTING TORQUE CONVERTOR
SHUDDER BUT ALSO MAY IMPROVE OTHER CONDITIONS LISTED ABOVE.
IF CAR IS A 86 OR 87 MODEL, ALSO ENSURE THAT IT HAS CORRECT MAF POWER AND
BURNOFF RELAYS AS LISTED IN REFERENCE G007.
G007
SUBJECT: MASS AIRFLOW RELAYS AND MAF TROUBLESHOOTING FOR 86-88 VIN F AND 8
SYMPTOM: CODE 33,34,OR 36 ( ANY OR ALL, HARD OR SOFT )ROUGH RUNNING, HARD
STARTING, ENGINE SURGE, AND STALLING
FOLLOW THESE STEPS TO TROUBLESHOOT A CODE 33,34,OR 36 ( INCLUDING POSSIBLE
FALSE CODES)ON ANY OF THE SUBJECT ENGINES WITH MAF SENSORS
1. MAKE SURE THE LATEST MAF RELAYS ARE BEING USED. THE CORRECT PART
NUMBERS ARE AS FOLLOWS:
86 CORVETTE - PR:10067925 BR:10094701
86-87 CAMARO,FIREBIRD - PR:10067925 BR:10094701
87-89 VETTE - PR:14089936 BR:14089936
CHECK VOLTAGE DROP ACROSS THE MAF POWER RELAY CONTACTS. IT SHOULD BE .2V
OR LESS
ALSO CHECK FOR LACK OF CURRENT FLOW (EXCESSIVE VOLTAGE DROP) ACROSS
CONTACTS OF MAF POWER RELAY AND BURNOFF RELAY WITH 12V TEST LIGHT. CHECK
CIRCUIT 993 FOR PROPER OPERATION OF THE POWER RELAY AND CIRCUIT 994 OF THE
BURNOFF RELAY. IF TEST LIGHT IS DIMMER THAN NORMAL WHEN CONNECTED TO
RELAYS AS EXPLAINED BELOW, THE RELAY MAY BE FAULTY.
TO DUPLICATE INTERMITTENT FAILURE, YOU MAY NEED TO CYCLE THE RELAYS
SEVERAL TIMES AS FOLLOWS:
CYCLE THE POWER RELAY BY STARTING THE ENGINE TO CLOSE THE RELAY AND THEN
STOPPING THE ENGINE TO OPEN IT. THE TEST LIGHT SHOULD LIGHT WHEN THE RELAY
CLOSES AND NOT LIGHT WHEN THE RELAY IS OPEN.
CYCLE BURNOFF RELAY BY RUNNING THE ENGINE TO NORMAL OP TEMP. IN CLOSED
LOOP AND THEN SHUTTING IT OFF. THE TEST LIGHT SHOULD LIGHT FOR A FEW
SECONDS AFTER THE ENGINE STOPS AS POWER IS APPLIED TO THE BURNOFF RELAY TO
MAF SENSOR.
IF CORRECT RELAYS ARE INSTALLED ON THE CAR AND OPERATING PROPERLY, CHECK
THE OTHER ITEMS LISTED ON THE FAST TRACK TROUBLESHOOTER CARTRIDGE. (DONT
HAVE THIS INFO YET BUT WILL ACQUIRE SOMEHOW HOPEFULLY.) |
