SERVICE MANUAL REVISION FOR EGR DIAGNOSTICS CODE 32

SERVICE MANUAL REVISION EGR SYSTEM ERROR CODE 32 SECTION 6E2

VEHICLE AFFECTED 1987-88 "L" CARLINE WITH 2.0L ----------------- (VIN 1) ENGINE

Please update your service manual to include Code 32 diagnostic chart and facing page in this bulletin.

CODE 32 EGR SYSTEM ERROR 2.0L (VIN 1) -L- SERIES (TBI)

Code Description:

A properly operating EGR system will directly affect the air/fuel mixture requirements of the engine. Since the exhaust gas introduced into the air/fuel mixture cannot be used in combustion (contains very little oxygen), less fuel is required to maintain a correct air/fuel ratio. If the EGR system were to fail in a closed position, the exhaust gas would be replaced with air, and the air/fuel mixture would be leaner. The ECM would compensate for the lean condition by adding fuel, resulting in higher block learn values.

The fuel control on this engine is conducted within 16 block learn cells. Since EGR is not used at idle, the closed throttle cell would not be affected by EGR system operation. The other block learn cells are affected by EGR operation, and, when the EGR system is operating properly, the block learn values in all cells should be close to the same. If the EGR system becomes inoperative, the block learn values in the open throttle cells would change to compensate for the resulting lean mixtures, but the block learn value in the closed throttle cell would not change.

The difference in block learn values between the idle (closed throttle) cell and cell 10 is used to monitor EGR system performance. When the difference between the two block learn values is greater than 12 and the block learn value in cell 10 is greater than 140, Code 32 is set. The system operates in block learn cell 10 during a cruise condition at approximately 55 mph.

Diagnostic Aids:

The Code 32 chart is a functional check of the EGR system. If the EGR system works properly but Code 32 has been set, check other items that could result in high block learn values in block learn cell 10, but not in the closed throttle cell.

Check for restricted or blocked EGR passages.

Perform a MAP output check. Follow the procedure in CHART C-10.

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.