Cylinder Miss On Left Turns And Cylinder 4 Miss On Right Turns - Possible Fuel Contamination - keywords CEL contaminated controls cylinders gas injector intermittent MIL misfire P0300 P0301 rail rust

This PI was superseded to update models. Please discard PIP3333.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

On rare occasions, an intermittent engine misfire may be experienced on cylinder 1 during/following a left turn or on cylinder 4 during/following a right turn. The misfire may / will typically last up to 10 seconds. A SES light and DTCs P0300, P0301, and/or P0304 may also be present if the misfire lasts long enough.

This may be the result of fuel contamination and is more likely to occur on vehicles with a returnless fuel rail because it is easier for fuel contaminates to become trapped in a returnless fuel rail since they do not have a fuel return line that returns fuel back to the fuel tank. As a result, any fuel contaminates that make it to the fuel rail tend to gather over the #1 fuel injector inlet when turning left and tend to gather over the #4 fuel injector inlet when turning right, causing this concern. The cylinder next to the fuel feed line (1 or 4 depending on the model) may also experience some random misfires at idle as contaminates enter the fuel rail from the fuel tank.

If the SI diagnostics do not isolate a cause for this concern, inspect the inside of the fuel rail and/or fuel tank for fuel contamination. If this concern occurs intermittently, it is unlikely that fuel contamination will be found by simply taking a fuel sample from the fuel feed line/fuel pressure test port. Typically, it will be necessary to turn the engine off as the misfire is occurring, carefully remove the fuel rail (while keeping the fuel in the rail), and drain it into a clear container for inspection. If this is not possible due to the intermittent nature of the concern, or if no fuel contamination is found by doing this, it may be necessary to inspect the inside of the fuel tank for fuel contamination.

Notice: The Aveo and Vibe have an access cover under the rear seat so the fuel pump module can be removed for inspection without removing the fuel tank.

If fuel contamination is present, refer to the "Fuel System Cleaning" procedure in SI and clean the inside of the fuel tank, fuel lines, and fuel rail. Once the repairs are complete, advise the customer to only use fuel from high quality, high volume Top Tier filling stations. Repairs made as a result of fuel contamination should not be considered as a warranty repair.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.