Grand Prix V6-191 3.1L (1989)
With a Techline Diagnostic Tool, read the throttle position sensor, manifold absolute pressure sensor, and A/C pressure transducer voltage with the key
on-engine off.
If all three voltage readings are skewed below their normal ranges, inspect the A/C pressure transducer.
If all three voltage readings are within normal ranges, disconnect the battery for one (1) minute, reconnect and start the engine. If the increase in engine
rpm at idle condition is gone, inspect the A/C pressure transducer.
NOTE:
On the LB6 (2.8L VIN W), LHO (3.1L VIN T) or L01 (3.4L DOHC VIN X) engines, If the ECM Is without battery power for any reason, then the
Idle air control valve (IACV) position information for a stable satisfactory engine Idle Is "lost" and replaced with a default value. To correct the
IACV position Information, perform an Idle relearn procedure using a Techline Diagnostic Tool. You can also manually relearn the Idle by following
the procedure below.
1.
Remove battery power for one (1) minute. Restore battery power and place air conditioning controls (if equipped) in the "off" position.
2.
Firmly apply the parking brake and block the drive wheels. Start the engine, shift the transmission to drive for automatics and neutral for manuals.
3.
Allow the engine to run until the engine cooling fan has cycled once, or a maximum of 10 minutes.
4.
Turn the ignition key to the "off" position for at least 5 seconds.
5.
Repeat Step 2.
6.
Allow the engine to run for at least five (5) minutes.
The correct IACV values for proper idle control will now be stored.
Technical Service Bulletin # 476510
Date: 940501
Engine - Diagnosing Intermittent Idle Speed Increases
Group Ref.: Engine Fuel & Emission
Bulletin No.: 476510
Date: May, 1994
INFORMATION
SUBJECT:
DIAGNOSING INTERMITTENT ENGINE IDLE RPM INCREASE
MODELS:
1988-89 BUICK CENTURY AND REGAL
1988-89 CHEVROLET BERETTA/CORSICA, CAVALIER AND CELEBRITY
1988-89 OLDSMOBILE CUTLASS CIERA AND SUPREME
1988-89 PONTIAC GRAND PRIX AND 6000
WITH 2.8L ENGINE (VIN W - RPO LB6)
1989-93 BUICK REGAL
1990 CHEVROLET CELEBRITY
1990-92 CHEVROLET CAMARO
1990-93 CHEVROLET BERETTA/CORSICA
1990-94 CHEVROLET CAVALIER AND LUMINA
1989-93 OLDSMOBILE CUTLASS SUPREME
1989-91 PONTIAC 6000
1989-93 PONTIAC GRAND PRIX
1990-92 PONTIAC FIREBIRD
1991-94 PONTIAC SUNBIRD
WITH 3.1L ENGINE (VIN T - RPO LHO)
1991-94 CHEVROLET LUMINA
1991-94 OLDSMOBILE CUTLASS SUPREME
1991-94 PONTIAC GRAND PRIX
WITH 3.4L ENGINE (VIN X - RPO L01)