P0272-CYLINDER 4 CONTRIBUTION/BALANCE

For a complete wiring diagram Refer to Section 8W

When Monitored:
With the ignition on.
Set Condition:
The Engine Control Module (ECM) is unable to stabilize fuel quantity in cylinder 4.

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

Diagnostic Test

1. CHECK FOR ACTIVE DTC

NOTE: If the ECM detects and stores a DTC, the ECM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the scan tool at the same time the DTC is displayed.

NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC.

With the scan tool, erase ECM DTCs.
Test drive the vehicle and attempt to duplicate the problem.
With the scan tool, read ECM DTCs.

Did this DTC set again?

Yes

Go To 2

Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

2. FUEL CONTAMINATION

Refer to the Service Information and inspect the fuel supply for contamination.

Is the fuel contaminated?

Yes

Refer to the Service Information to remove and replace fuel throughout the fuel system.

Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To3

3. CHECKING THE SUPPLY SIDE FUEL DELIVERY SYSTEM

Refer to the symptom Checking the Fuel Supply System and test for proper Fuel pressure from the fuel tank to the high pressure Fuel Injection Pump.

NOTE: The following is a list of problems that can cause fuel pressure to deviate from specification: restricted fuel filter or fuel lines, air in fuel system, failed fuel sending unit, contaminated fuel.

Were there any problems with the Fuel Delivery System?

Yes

Repair as necessary in accordance with the Service Information.

Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 4

4. ENGINE COMPRESSION

Ignition on, engine off.
Refer to the Service Information and perform the Cylinder Compression Test.

Is the cylinder compression within specification for all cylinders?

Yes

Go To 5

Repair as necessary in accordance with the Service Information.
Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

5. FUEL INJECTOR CIRCUIT RESISTANCE

Turn the ignition off.
Disconnect the ECM harness connectors.
Disconnect each Fuel Injector harness connector.
Measure the resistance of each of the Fuel Injector Control circuits between the Fuel Injector and ECM harness connectors.

Is the resistance below 10.0 ohms for each measurement?

Yes

Check the intake system for air leaks that could affect this cylinder. If found, repair intake system leak as necessary. If o.k. replace the Fuel Injector.

Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Repair the Fuel Injector circuit(s) that measured above 10.0 ohms for an open.
Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)