Engine Controls - Intermittent No Start or Driveability

91chevy18

Number: 89-327-6D

Section: 6D

Date: MAY 1991

Corporate Bulletin No.: 138111


Subject: INTERMITTENT NO START, LONG CRANK, STALL, OR ENGINE SURGE


Model and Year: 1988-89 CORVETTE


Condition:

On the 1988-89 Y Car, the engine may have intermittent no start, long crank times, may start and stall after start, or may have engine surge or rough running. No codes will be set, and no trouble can be found using normal diagnostic procedures.

Cause:

The relay used for production, P/N 14103304, may not conduct enough current to allow the Mass Air Flow (MAF) circuits to operate properly. The relays will test OK.

Correction:

Both the MAF relays (Burn-off and Burn-off control) should be replaced with relay P/N 14089936. This relay is serviced with a bracket, which is used only for 1988, and can be discarded for the 1989 model year. The location of the relays is shown on page 8A-20-9 of the 1988 and 1989 Y Car Service Manual.

Pad is currently available from GMSPO.

The O2 sensor may also be carbon-coated because of this condition. To clear the carbon, apply the parking brake, and allow the engine to warm up to normal operating temperature. Then hold the RPM at 1800 RPM for three minutes.

Warranty Information:

Use applicable labor operation.