Poor Cold Performance - Replace Engine Controller (18-86-91)

POOR COLD PERFORMANCE - REPLACE ENGINE CONTROLLER

TECHNICAL SERVICE BULLETIN

COLD ENGINE POOR PERFORMANCE/SAG OR SURGE ON ACCELERATION

Model 1991-92 (BB) Premier Equipped With Single Board Engine Controller (SBEC II)

Group Engine Performance

Bulletin No. 18-56-91

Date September 9, 1991

S ymptom Cold Engine Poor Performance/Sag Or Surge On Acceleration

SERVICE INFORMATION

1991 vehicles built after MDH 10-08-XX are equipped with a SBEC II. These vehicles can be identified by an eight in the twelfth position of the VIN.

SYMPTOM/CONDITION:

The vehicle will exhibit the two following conditions. First, the engine will sag and/or pop back during the first aggressive throttle tip in. This will happen within the first ten seconds of a cold engine start up when the ambient temperature is between approximately 60°F - 90°F (15°C - 32°C). Second, with the engine fully warm, the vehicle will exhibit a surge while traveling 30-40 MPH (50-65 KM/H).

DIAGNOSIS:

Verify that the system is functioning as designed using the appropriate diagnostic test procedure.

QTY.	DESCRIPTION	PART NUMBER
1	Engine Controller	4605101
1	Authorized Modification Label	4275086

REPAIR PROCEDURE:

This procedure involves replacement of the engine controller (SBEC) with a revised engine controller.

1. Replace the original engine controller with the revised engine controller (4605101).
2. Type an Authorized Modification Label, PN 4275086 as shown in Figure 1 and attach near the VECI label.