Citation II V6-173 2.8L VIN X 2-bbl (1985)
Technical Service Bulletin # 852026E
Date: 860501
PROM - Check Engine Light Code 34, Surge. Hesitations
Number:
85-202
Section:
6E
Date:
MAY, 1986
Subject:
CHECK ENGINE LIGHT (CODE 34), ENGINE SURGE, ENGINE HESITATIONS
Model and Year:
1985 CELEBRITY, CAVALIER & CITATION MODELS
(VIN CODE W) AND 1985 CAMARO MODELS WITH LB8 2.8L MFI ENGINE (VIN CODE S)
TO:
ALL CHEVROLET DEALERS
Customer comments may be received on some 1985 cars with the 2.8L MFI engine regarding check engine light (Code 34), engine
surge, or engine hesitation. Listed below is some information that should help to correct each condition.
Problem Identification
Item # 1. Check Engine Light (Code 34) Code 34 will set if the following conditions are met:
^
Engine running
^
Mass Air Flow sensor (MAF) disconnected, faulty relay or MAF signal circuit shorted to ground. Or
^
Air flow less than 2 grams per second (low frequency)
To correct a Code 34 check engine light, first make sure that the MAF relay is working and supplies + 12 volts to the MAF sensor. This can be
accomplished by connecting a test light between ground and the "+" terminal of the MAF sensor harness. With the ignition "on", the test light should
light. If the light doesn't light, check for an open in the + 12 volt supply or a faulty relay.
If the power is supplied to the MAF sensor, use the standard fault tree for check engine light (Code 34) in Section 6E3 of the Service Manual.
Item # 2. Engine Surge Item # 2A. If the vehicle exhibits surge, follow procedures in Section B - Symptoms, Section 6E3 of the Service Manual for
diagnosing surge. Particular attention should be given to:
^
Checking rear spark plug wires for heat damaged wires. Replace if damaged.
^
Checking spark plug wire boots for evidence of carbon tracking. If carbon tracking is present in spark plug boot replace both spark plug and
spark plug wire.
Item # 2B. If the surge does not go away, update of the following parts should correct the condition.
^
Install the latest PROM unless the vehicle already has it. (This can be done by using Chart I).
The latest PROM has revised EGR scheduling when the torque convertor is locked. This should reduce surge.
^
If the car is a Chevrolet Celebrity, Pontiac 6000 or Pontiac STE, install a new air cleaner housing which has a honey cell flow straightener.
This is provided in a service kit (Part Number 25097022) which contains the air cleaner housing, gasket, and clamp.
After installing this new housing the car should be parked and the engine allowed to cool to ambient temperature. Then it should be cold
started and driven a minimum of three miles to update the ECM memory.
NOTICE:
During the first cold start after installing the new air cleaner housing the engine may hesitate and possibly backfire until the ECM
memory is updated.
Item # 3. Engine Hesitation If the engine exhibits hesitations during accelerations when the engine is cold, update the following parts to correct the
problem.
^
Install the latest PROM unless the vehicle already has it. (This can be done using Chart I).
^
If the vehicle has early production injectors, install the updated injectors which have a revised spray pattern. The updated injector is part of a
kit P/N 1711297, (six) 6 kits required per engine.
