Nightlifephantom

Hey C5 crew, before I get eaten alive by some of you... I know I own a C6 and this is the C5 section. I've posted in the C6 section and haven't received much help but since some C5 owners share a similar 4.2 motor as I have, I figured I would try my luck here. Any help would be appreciated guys. Thank you!

Here is the link to my original post:

https://www.audiworld.com/forums/a6-...fires-2933215/

Harleyguy

Looked at your original post. Kinda looks like an intake leak causing the misfires.

Nightlifephantom

As in intake box/boot leak or manifold leak?

Harleyguy

Could be any of those. Most common seems to be the rubber "plumbing" for the intake. These hoses tend to develop splits and cracks that are next to impossible to locate. Seems to often be on the underside and usually small enough that you can barely see them.Many use a smoke test to see if the smoke is being sucked in from an inappropriate location. Other methods are used but can be a problem if you don't use extreme caution. Applying a small amount of propane from a handheld torch canister in the suspected area with the engine running can be useful if care is exercised. If a leak is present the engine rpm will change as it sucks in the extra fuel. Again this can be very risky as any stray spark or heat source can ignite the gas. I would recommend a thorough inspection of the intake tubing as the first step, looking for loose hose clamps, splits, cracks, etc.

Nightlifephantom

I replaced the whole throttle body and also intake boot, coils, plugs. My shop smoke tested the vacuum lines but we couldn't find anything after a few minutes of smoking. Just really frustrated at this point... back in February I did valve cover gaskets, timing belt, oil cooler o rings and my shop did other front seals as well. My guess at this point is either manifold gasket leak, fuel issue, a missed damaged vacuum line, timing issue (maybe valve solenoid). But I don't want to be throwing parts, time and money into something that's not broken... I was hoping someone encountered this issue before and know of a solution.

Does anyone know where the bank 1 valve solenoid is located and how to remove it? I think that might be my next approach.

4Driver4

The 4.2 in the C6 is really nothing like the 4.2 in the C5. Most C5s run a timing belt engine; only the Allroad has a chain engine like the C6. The C6 is FSI, while the C5 is not. I doubt you'll find much help here.

raj99

Good points 4driver, the only clarification is that the 05 & 06 C6 4.2 is not fsi... So doesn't suffer from carbon buildup issues.

Nightlifephantom

Ah. I had the impression that the C5's we're pretty similar. I ended up posting in the B6 S4 section after doing a little research. Thank you