califphil

Vehicle
2008 Chevrolet HHR SS 2.0L Turbo

Title
Misfire at idle and driving, replaced duct.

Complaint
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.

Cause
Found big hole in ductwork coming from turbocharger.

Correction
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.

Oldblue

Great , thanks for your advice on this.

donbrew

Just like the advice we always give "look for air leaks"

PulpFriction

Thank you!

Leaks between the Turbo and TB are a frequent topic on FB HHR SS groups. Most often it's a crack in one of the plastic ends on the intercooler. ZZP's all-metal options are then discussed. Me, I'd be inclined to exercise my modest fiberglass skill.