2.7t misfires

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Old 10-27-2004, 04:23 AM
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Default 2.7t misfires

I've seen more than a few posts about symptoms like <a href="https://forums.audiworld.com/s4/msgs/1780858.phtml">this</a>, but haven't seen any solution to it. Mine does it now and then.

I also have a crappy old stock flywheel that chatters at times, as well as a slightly imbalanced rs4 clutch disc.(not that bad anymore) Is there any relation to this? I've checked for leaks and checked out the power brake assist, it doesn't seem to have any vacuum leaks.

I've also seen posts claiming <a href="https://forums.audiworld.com/s4/msgs/1453801.phtml">bad head</a>, but I'm in denial over that possibility, idles just fine when stationary and hot.
Old 10-27-2004, 06:08 AM
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Default i've heard audi meachanics talk about the 2.7t misfire

some say it happens "just because"
Old 10-27-2004, 06:48 AM
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Default that's silly

:P

I wonder if the 2.8 does it, and if it doesn't, is it the heads or the cams that make it not?

Do you think the misfire on decel under 5mph is from the driveline getting slack as it goes from engine braking to powering and the broken dual mass flywheel becomes unbound and "lighter"? If you know what I mean.

I'm half tempted to find my old bosch sensor element and stock housing and try stock ecu and injectors. Not sure I have any good bosch elements though.
Old 10-27-2004, 06:13 PM
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Default

I would have to say plugs, and then MAF hose leak. Would say the gap is too big, in both cases . ..
Old 10-28-2004, 04:36 AM
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Default See, that's the odd thing, it's done it on ik22s, f5dp0rs, pfr6qs, two different code bases,

two different maf housings/hoses, it passes pressure checks. .029-030" gap on gappable plugs.

At least in reference to the sub 5mph stumble while slowing down.

I think cold idle/startup misses are licked now.


Only thing I haven't tried is capping off the pcv.

It's not too bad on my current setup so far, I can notice it, but it doesn't have the wtf factor.

Weird thing about it is, if it's happening with the clutch depressed, the moment the car stops, the rough idle stops, without changing the brake pedal position either. ABS related?

Some day I'll look into it more, double check what I've double checked. It's pretty subtle lately, I can provoke it though. FWIW I have no missing on full boost with any of the listed plugs, even at 1.65bar.

If I find anything I'll be sure to post it.
Old 11-11-2004, 03:08 AM
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Default Try capping the PCV. When I had a leak in the PCV system, the missfires were out of control...

and sealing the leak obviously made it better. It's worth a try.
Old 11-11-2004, 08:15 PM
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I was thinking about that at some point, never did it and forgot, thanks for the memory jog
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