Fuel - Engine Misfire/Rough Running In Cold Weather

Classification:
EC96-017

Reference:
NTB96-114

Date:
December 23, 1996

1993-97 TRUCK ENGINE MISFIRE/ROUGH RUNNING DURING COLD WEATHER OPERATION

APPLIED VEHICLES:
1993-94 Truck (021) with KA24E, CA models only
1995 Truck (021) with KA24E, CA
and Federal models 1996-97 Truck (D21) with KA24E (all)

SERVICE INFORMATION

This bulletin describes how to repair an engine misfire/rough running condition if it occurs on a 1993-97 Truck with a KA24E engine when operated in ambient temperatures of 32 degrees F (0 degrees C) or less. 1996-97 Trucks may have the Malfunction Indicator Lamp (MIL) On," with Diagnostic Trouble Code (DTC) P0303 (# 3 cylinder misfire) stored in the Engine Control Module (ECM) after the misfire/rough running incident occurs.

The cause may be ice forming on the tip of the # 3 injector during engine warm up. The repair consists of intake manifold replacement on 1993-95 Trucks and, for 1996-97 Trucks, intake manifold and ECM replacement. Perform the following SERVICE PROCEDURE to diagnose and repair the vehicle.

SERVICE PROCEDURE

1. Confirm the # 3 cylinder is misfiring as follows:

^ 1993-95 Truck: Disconnect the cylinder # 3 injector connector.

^ 1996-97 Truck: Use CONSULT set to ACTIVE TEST, POWER BALANCE to disable the cylinder and verify the incident..

2. 1996-97 Truck: Perform TROUBLE DIAGNOSIS FOR DTC P0300 - P0304, using the appropriate service manual.

3. If the cause for # 3 cylinder misfire/rough running cannot be determined using step 2, perform the appropriate following step:

^ 1993-94 Truck (CA only). and 1995 Truck (CA and Federal): Replace the intake manifold.





^ 1996-97 Truck: Replace the intake manifold AND the ECM. The improved intake manifold (P/N 14001-0S301) MUST be used in combination with the improved ECM. (Figure 1 on the following page shows the improved intake manifold P/N location.)





PARTS INFORMATION

CLAIMS INFORMATION





A Submit a Primary Failed Part claim using the coding as shown.