4.2L cylinders 5, 6, 7, and 8 misfiring help please

[Detroit]

So I have a 2007 Audi Q7 with the 4.2L V8 that is not idling smoothly and has the following codes.

Random/Multiple Cylinder Misfire Detected P0300 Upper Limit Reached - Intermittent.

Cylinder 8: Misfire Detected P0308 Upper Limit Reached - Intermittent.

Cylinder 6: Misfire Detected P0306 Upper Limit Reached - Intermittent.

Cylinder 5: Misfire Detected P0305 Upper Limit Reached - Intermittent.

Cylinder 7: Misfire Detected P0307 Not A Plausible Signal - Intermittent.

I unplugged be Oxygen Sensors to see if it would smooth out but it did not. I changed the coils from 5, 6, 7, 8 to 1, 2, 3, 4 to see if the codes changed but they did not. I also replaced the plugs with new ones and that didn't help. Hoping someone here might be able to help.

[Corners4kids]

Possibly MAF sensor. I got some of those codes a few thousand miles after I changed plugs and coil packs on my S5 4.2. Cleaned the MAF sensor (CRC makes a great spray cleaner) and it solved it for me. Might need a new part, but the cleaner is a cheap thing to consider trying.

Just a thought. Might not be it, but it's an inexpensive option to test.


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[staypuft]

Check plugs & coil packs for those cylinders.

Had this with mine, new plugs and coil packs and runs super smooth now.

[Sofreshs5]

Carbon clean it. If it still persist then replace all injectors.

[James1972]

What was out come?

[James1972]

So what was out come, I’ve got a 2008 Q7 4.2 doing same thing

[zfoot]

Same thing happening to my Q7. Any word ?

[3g_bishi]

It’s gonna be an upstream o2 sensor on that side, or a vacuum leak on that side.


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[zfoot]

What about the mass airflow sensor?

[3g_bishi]

Buy some mass air flow sensor cleaner and try it but if it was maf it would miss on both sides.


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[nighthawk86]

Possible bad bank 2 cam tensioner. Should also see a p0321 code I believe if it’s that

[volvofan]

It’s gonna be an upstream o2 sensor on that side, or a vacuum leak on that side.


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Having same issue on my s5 but on bank 1. Anything you can check in VCDS to nail it down to the O2 sensor?

https://www.audizine.com/forum/showt...on-Bank-1-only