Engine Controls - Stalls, Hesitation, Poor Driveability

Model:
700-900

Group:
28

Number:
113

Title:
MFI Regina Control Module Replacement For Cold Start Symptoms 1989-1993 Regina/Rex B230F W/Auto. Trans.

Market:
Us and Canada

Date: August 1993

This Bulletin Supersedes SB 28-113; Dated July 1993.

Reference:
TP 31903/1 (English); 9/91/ Fuel System Regina Ignition
System REX-I
SB 25-202/704; 5/91
SB 28-710; 8/92
SB 28-205/906; 3/93
SMB 23-26; 8/92

Multi-port fuel injection (MFI) Regina control module replacement for cold start symptoms with low volatility fuel.

BACKGROUND:
Some of the low volatility fuels (also known as low RVP fuels) now used during the May- September time period suffer from decreased mid-range volatility. This decreased mid-range volatility can result in the need for repeated cold start attempts in ambient temperatures ranging from 60-85°F (16-27°C).


SYMPTOMS:

- The engine starts OK, but stalls almost immediately, requiring a restart attempt.
- A drop in idle RPM or stall when A/C compressor and electric cooling fan engages.
- Take-off hesitation immediately after a cold start.
- The condition began in May, and only occurs within the first 30-40 seconds after a cold start on a cold engine, not on a warm engine.

DIAGNOSTIC PROCEDURES:




Follow the diagnostic flow chart. Any pre-existing out-of-line condition will only aggravate the above described conditions and should be corrected before proceeding further. Out-or-line conditions Include poor compression, incorrect valve clearance, intake valve deposits, injector deposits, etc.

All vehicles with the Regina/Rex engine management system will have the new MFI Regina control module from the 1994 model year production start. If the vehicle already has MFI control module, p/n 5003946-0 or 9146261-4 the update has already been performed.

REPAIR PROCEDURES:




If a confirmed customer complaint is diagnosed after any out-of-line conditions have been corrected, an updated MFI Regina Control Module is available for vehicles equipped with the Regina/Rex engine management system. See chart.

Replacement of fuel injection control module

Procedure:

Record any fuel injection and ignition system diagnostic trouble codes (DTC) and correct faults as required.

Ignition should be switched off.

Remove/disconnect:




- front screw in sill protector (1)
- cover over MFI control module (2)

Caution:
Module must be dead when connector is removed or reconnected, otherwise damage may result. Remove Fuse no. 1 to avoid damage to control modules.




Disconnect 35-pin connector from module.

Remove old MFI Regina control module.

Install updated MFI Regina control module, p/n 5003946-0




Reconnect connector to module.

Reinstall:




- cover over control module (2)
- screw in sill protector (1)

Check for new DTCs (if any).




WARRANTY STATEMENT:
Replacement of control module may be performed once for this condition - under the Emission Control System Warranty using claim type: 02.