MANUAL UPDATE-SECTION 6E3-C7-4 (EGR FLOW CHECK)

MODELS AFFECTED: 1988 RIVIERAS AND REATTAS EQUIPPED WITH 3800 ENGINES (VIN CODE C)

The chart on the reverse side updates the Exhaust Gas Recirculation (EGR) Flow Check found on page 6E3-C7-4 of the 1988 Riviera and Reatta Buick Chassis Service Manual.

Terminals "A" and "C" are reversed on the original chart and should be revised to show this information.

CHART C-7 EXHAUST GAS RECIRCULATION (EGR) FLOW CH ECK 3800 (VIN C) "E" SERIES (PORT)

Circuit Description:

The digital (EGR) valve is designed to accurately supply EGR to an engine independent of intake manifold vacuum. The valve controls EGR flow from the exhaust to the intake manifold through three orifices which increment in size to produce seven combinations. When a solenoid is energized, the armature, with attached shaft and swivel pintle, is lifted opening the orifice.

The flow accuracy is dependent on metering orifice size only, which results in improved control.

Test Description:

If a code is set, inspect EGR for damage.

Start and idle engine, enter ECM overrides ES02, ES03, ES04. You should be able to discern a change in engine rpm as the ECM turns on the EGR.

ES02 should result in a small change and ES04 in a large change in rpm. The engine may stall when ES04 is turned "ON."

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.