Engine - Surge After TCC Lock, Detonation, False DTC 53

Number 86-6 (Gasoline)-73 Date 5/87

Subject: DRIVEABILITY PROM: SURGE, DETONATION

AND FALSE CODE 53

1986 GRAND PRIX AND BONNEVILLE MODELS WITH

5.0L ENGINES (LG4) AND THM-200-4R

TRANSMISSIONS (ENGINE CODE H)
On some 1986 Grand Prix and Bonneville models with the 5.0L (LG4) engine and 4 speed automatic transmission (MW9) may experience the following customer comments of:

1. Surge after TCC lock-up.

2. Detonation on light acceleration.

3. False Code 53 - EGR Control Error

If normal service procedures in the Shop Manual do not correct, a new service PROM with revised calibration is now available.

The model application are:

Service
Year Model Engine Trans. Emissions PROM P/N

1986 Grand Prix 5.0L 4 Spd. California 1228478
Bonneville Auto

1986 Grand Prix 5.0L 4 Spd. Federal 1228479
Bonneville Auto

Use applicable labor time and operation numbers.