Tech 1 ECM Cartridge - Usage

90pontiac21
Bulletin Number: 91-6-15
Reference Number: 016541
Publish Date: 11/90
Subject: USE OF 1987-91 TECH 1 ECM CARTRIDGE AND PROCEDURE

Models

Affected: 1987-91 6000, FIREBIRD AND GRAND PRIX WITH 2.8L (LB6) 3.1L (LHO) SPEED DENSITY
This bulletin is a revision to the Tech 1 Diagnostic "Scan" Tool 1987 thru 1990 ECM Cartridge.

The 1987-1990 ECM Cartridge will not allow the Idle Learn Procedure to function properly. When performing an Idle Relearn on all 1987-1991 6000, 1988-91 Grand Prix and 1990-91 Firebird models equipped with a 2.8L (LB6) or 3.1L (LHO) speed density (PFI) engine, you must use the 1987-1991 Tech 1 ECM Cartridge or the following procedure.

NOTICE: IF THE ECM IS WITHOUT BATTERY POWER FOR ANY REASON, THE IACV POSITION INFORMATION FOR A STABLE SATISFACTORY ENGINE IDLE IS "LOST" AND IS REPLACED WITH A "DEFAULT" VALUE.

To restore the lost IACV position information due to an absence of battery power, perform the following procedure:

1. Restore the 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, and shift the transaxle to "drive" for automatics or "neutral" for manuals.

3. Allow the engine to run a maximum of 10 minutes or until the engine cooling fan has cycled once, whichever occurs first.

4. Shift transaxle to Park (A/T), Neutral (M/T), turn the ignition key to the "off" position for at least 5 seconds.
5. Repeat Step # 2.

6. Allow engine to run for at least 5 minutes.

This procedure will allow the ECM memory to be updated with the "correct" IACV position and provide a stable idle quality.