Correct fuel and air ratios are the key to any engine running properly. Many factors can mess up this ratio and cause problems but even with them correct, you can still have issues that seem like that is the cause. SureTrack community member locustpoint had a Chevrolet HHR Turbo in their shop that was running poorly and smoking and the car had been parked for four years. They posed the question to the community, and with the help of fellow community member DAG1365 and others, they were able to resolve the issue quickly.
The following Community Fix summarizes the interaction between members of the community that led to the solution.
2008 Chevrolet HHR SS 2.0L Turbo
Misfire at idle and driving, replaced duct.
Customer states engine runs rough and check engine light on.
Diagnostic Steps Performed/Parts Replaced
This car has been sitting for four years. Verified customer’s complaint and found code P0300. When I unplug the mass airflow sensor (MAF) it will idle okay. But when you give it gas it seems like it is plugged up. It is also running rich, the spark plugs are black and it smokes. I can’t check the fuel trims because I don’t run it long enough to get in closed loop. When I did the injector balance test, the PCM only activated the injectors for about 1 second, if that. The fuel pressure only dropped about 4 psi on all injectors. Is that normal? I don’t think it is starving for fuel but will be replacing the fuel today. Any suggestions would be great.
Best Answer from Community Member DAG1365
Check for exhaust restrictions, engine coolant temperature (ECT) readings, fuel pressure readings, and check MAF readings when running. Be sure the grounds are good.
Found big hole in ductwork coming from turbocharger.
Replaced damaged turbocharger ductwork, changed spark plugs, replaced stale gasoline with fresh and changed the engine oil. Code did not return and vehicle runs as it should.
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