ENG. MAY INTERMITTENTLY STALL CHECK FOR RESIDUE ON THROTTLE

VEHICLES AFFECTED: 1985-86-87 'A, J AND F' CARS AND 1987 'L' CARS EQUIPPED WITH 2.8L V6 PFI ENGINES

Some 1985, 86 and 87 vehicles equipped with 2.8L V-6 engines may experience a stall after start with a warmed up engine or a stall during deceleration.

This condition may be caused by residue accumulating inside the throttle body bore behind the throttle plate and limiting air flow past the throttle plate in the idle position.

To diagnose this condition, perform the following steps:

1. Measure minimum idle speed using procedures defined in Section 6E3 of the service manual.

2. If the minimum idle speed is less than what is specified in Chart I below, proceed to Step 3. Otherwise, perform activities defined in the service manual under Section 6E3, Section B - Rough, Unstable or Incorrect Idle, Stalling.

CHART I - MINIMUM IDLE SPEED

Model Year Car Line (s) Minimum Idle @ee

85/86 A, J, F 550 + or -50 RPM in drive (auto. trans.) 650 + or -50 RPM in neutral (man. trans.)

1987 F 550 + or -50 RPM in drive (auto. trans.) 650 + or -50 RPM in neutral (man. trans.)

1987 A, J, L 550 + or -50 RPM in drive (auto. trans.) 675 + or -50 RPM in neutral (man. trans.)

* Engine should be at normal operating temperature.

3. Remove the negative battery terminal.

4. Remove mass airflow duct at throttle body.

5. Cover TPS and IACV to protect from overspray.

6. Clean the throttle body bore in the area behind the throttle body. Use a shop towel with GM Top Engine Cleaner, P/N 992872, or AC-Delco Carburetor Tune-Up Conditioner, P/N X66-A, or equivalent that does not contain methyl ethyl ketone.

It should be noted that what appears to be a small amount of accumulation can be enough to limit air flow.

7. Install mass airflow duct.

8. 1987 model year vehicles built after the following VIN breakpoints will will not require checking and resetting of minimum idle speed.

1987 Model Year VIN Breakpoints

Carline Chevrolet Pontiac Oldsmobile Buick Cadillac

A G146967 9244354 D375524 D442400 6181561 T244412 G313565 6424153 9165041 9350538 T429618

J 7160371 K317556 J509271 J175417 K134154

L Y106246

F N139297 N224963 L123884 L215142

Recheck minimum idle speed on 1985 and 1986 vehicles, and 1987 vehicles built prior to the above VIN breakpoints. Adjust if necessary to specifications defined in step 2 above.

Use applicable operation number and charge 0.5 hours.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.