Cutlass V6-189 3.1L VIN T FI (1990)
Engine Control Module: All Technical Service Bulletins
ECM - Revised Fuel Cut-Off Specifications
NUMBER:
91-T-97
CORP.REF.NO: 116508
DATE:
April 1991
SECTION:
6E3
SUBJECT:
SERVICE MANUAL UPDATE REVISED FUEL CUT-OFF SPECIFICATIONS
MODELS/YEARS:
1990-91 CUTLASS SUPREME
WITH 3.1L OR 3.4L (VIN T,X) ENGINE
1990-91 WITH 3.1L ENGINE:
To prevent possible engine damage from over-speed the Engine Control Module (ECM) "cuts-off" fuel from the injectors when engine speed is above
approximately 6200 RPM with the vehicle in any forward gear or reverse, and approximately 4000 RPM in park or neutral. To prevent tire damage, the
ECM also has a fuel cut-off in excess of 100 mph (161 km/h) based on speed rating of the tires.
1991 WITH 3.4L ENGINE:
To prevent possible engine damage from over-speed the Electronic Control Module (ECM) "cuts-off" fuel from the injectors when engine speed is above
approximately 6500 RPM with the vehicle in any forward gear or reverse, and approximately 3000 RPM in park or neutral on vehicles equipped with
automatic transmissions. On vehicles equipped with a manual transmission the fuel is cut-off at approximately 7000 RPM. To prevent tire damage, the
ECM also has a fuel cut-off in excess of 120 mph (193 km/h) based on speed rating of the tires.
When diagnosing any suspected fuel cut-off problems, carefully compare Tech I (Scanner) engine RPM versus actual RPM. If the ECM is prematurely
sensing RPM or vehicle speed in the fuel cut-off range it may be due to Electro-Magnetic Interference (EMI) or other electrical "noise". Thoroughly
investigate harness routings and aftermarket equipment installations in these cases.
