COLD/HOT ENGINE RE-START DETONATION /ROUGH IDLE. GMC Truck S15 Pickup - 2WD 1991

For 1990-2009 cars

# COLD/HOT ENGINE RE-START DETONATION /ROUGH IDLE

#### SUBJECT: COLD ENGINE OR HOT ENGINE RESTART DETONATION OR IDLE ROUGHNESS DUE TO LEAN CONDITION (NEW CALIBRATION)

#### VEHICLES AFFECTED: 1990-91 'S' TRUCK

#### Condition:

---------- Some owners of 1990 and 1991 S trucks with 2.5L engines (VIN Code E) may comment of an engine detonation or idle roughness when cold or after a hot restart.

#### Cause:

------ The Production calibration has a temporary lean condition when the engine is cold or after a hot restart.

#### Correction:

----------- New MEMCALS have been released which address this temporary lean condition. Install the correct MEMCAL from the chart below:

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

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