Hello everyone,
my 2007 Q7 4.2 has had a misfire problem for a while now. I have had the dealer try to diagnose it and I feel like their just throwing parts at it, and its not fixing the problem. It has 110k on it and it have never had a carbon cleaning so i'm going to clean the valves this weekend and see if that fixes it. My question is does anyone know if there is a way to check the injector seals? It would be nice to know if I need to replace any of the seals while the intake is off so I don't end up pulling it a second time.

 

If you had a leaky injector seal, you would get an OBD code indicating a "lean" condition. I had a misfire issue a couple of years ago that turned out to be crappy spark plugs. One or two had "glazed". If you're getting the misfire on acceleration, that could very well be the issue.

Check out my post about it from a while back. https://www.audiforums.com/forum/gen...k-plug-218806/

 

Thank you Dave that is very helpful.
I don't have a lean condition code just misfire codes on 6 of the 8 cylinders and a random misfire code.
I guess I should have included all that stuff the dealer has done so far to try to clear up the problem. So far they have;
-ran some sort of cleaner through it to clean the carbon
-Replaced an intake runner solenoid.
-Replaced the in tank fuel pump and filter.
All to the tune of about 2600.00 and honestly the car have never ran worse.
I usually do all my own wrenching but I've been extremely busy at work lately.
When I bought the car I replaced the plugs with oem Ill pull them and check to see if their glazed as you suggested.

Ill check the codes one more time before I tear into it and be sure there is not a lean condition code. if I still don't have one then Ill leave the injector seals alone.

 

Thank you Dave that is very helpful.
I don't have a lean condition code just misfire codes on 6 of the 8 cylinders and a random misfire code.
I guess I should have included all that stuff the dealer has done so far to try to clear up the problem. So far they have;
-ran some sort of cleaner through it to clean the carbon
-Replaced an intake runner solenoid.
-Replaced the in tank fuel pump and filter.
All to the tune of about 2600.00 and honestly the car have never ran worse.
I usually do all my own wrenching but I've been extremely busy at work lately.
When I bought the car I replaced the plugs with oem and have since tested all the coils.

Ill check the codes one more time before I tear into it and be sure there is not a lean condition code. if I still don't have one then Ill leave the injector seals alone.

 

I spent $600 on various parts including a new fuel pump. Of course that would have been $2000 worth of labor if I had to pay someone else to do it. Turned out to be 2 glazed plugs.... They were relatively new, just a few months old. I had an O2 sensor issue on that side (bank 2) previously. I think that is what caused the heat condition that glazed them.