Engine - Cold or Hot Restart Roughness

91chevy12

GMC NUMBER: 91-6E-90

GROUP: 6E Engine Emission

DATE: May, 1991

CORPORATE
NUMBER: 136507


SUBJECT: COLD ENGINE OR HOT ENGINE RESTART DETONATION OR IDLE ROUGHNESS DUE TO LEAN CONDITION

MODELS: 1990-91 S1 TRUCKS WITH 2.5L ENGINES (VIN CODE 3)


Some owners of 1990-91 S1 trucks with 2.5L engines (VIN Code E) may comment about engine detonation or idle roughness when cold or after a hot restart. The production calibration has a temporary lean condition when the engine is cold or after a hot restart. New MEMCALS have been released which address this temporary lean condition. Install the correct MEMCAL from the chart below:

Broadcast
Model Engine Trans Axle MEMCAL P/N Code Scanner I.D.
S1 2.5L LN8 MAN 5 SPD 3:73 16159046 AXAA 9041
S1 2.5L LN8 MAN 5 SPD 4:11 16159047 AXAB 9051

Parts are currently available from GMSPO.

WARRANTY INFORMATION

Labor Operation: T0500

Labor Time: 0.7 hr.