Stutter ("hesitation") on HWY upon Acceleration

[Operator]

So I picked up my car from a recent caliper fix at the shop, and not 10mins later something new popped up......

I merged onto the HWY and my car started to stutter upon heavy acceleration. There sounded like a pop pop pop out from the exhaust and a poof of black smoke. I got off the gas, and tried acceleration again a mile down the road, and the car stuttered. Waited another 5 miles, and tried once more and the car acted as if it never had a problem?!? The next morning, I took off on the HWY and the problem came back, "hesitation" upon heavy acceleration. It's Sat, so the dealership and the European Automotive shop I use were closed. Took the car into Autozone, Advance Auto Parts, and O'Reilly's, code read-outs are P0441 Evap Emissions Control Sys Purge Flow Fault / P0300 Random Multiple cylinder misfire / P0301 cylinder 1 misfire (pending) / P0302 cylinder 2 misfire

Couple weeks ago, I had the N80 valve changed out at the dealer. Only other thing that was recommended, was changing the gas cap, but I find it odd that a bad gas cap seal could cause this problem.

I've already had my coil packs R² last year. And I plan to have my shop check my cam follower. Any other thoughts?

[kristokes]

Did your CEL go on at all?

[Operator]

Yeh, the CEL, came on. That's what made me think to pull the codes. Haven't tried to clear it.

[kristokes]

What year and how many miles? Try swapping out the spark plugs for the misfire and go from there.

[your daddy]

plugs and coils.

[Operator]

2007 54k. I'll try the plugs, as for the coils, all 4 were changed out last year by the dealer.

[kristokes]

I get the occasional "pop pop pop" (as you described it) but it's backfire due to the fact I have no catalytic converter. But I don't get that sudden hesitation during WOT. But please keep us updated on the situation; would like to know what the shops' diagnostics are.

[Operator]

I also have no Cat, but never experienced this situation before now. And I plan to just order a gas cap on top of getting diagnosed at the shop. As I have also been getting the "close gas cap" warning, off and on.

[kristokes]

I also have no Cat, but never experienced this situation before now. And I plan to just order a gas cap on top of getting diagnosed at the shop. As I have also been getting the "close gas cap" warning, off and on.

Just get the gas cap re-pressurized. That should help with the gas cap warning.

[Operator]

But please keep us updated on the situation; would like to know what the shops' diagnostics are.

Well I ordered the new revised gas cap and installed it, got the codes cleared out, and so far so good. But I'm still weary of the mis-fire codes, wasn't able to duplicate them for the shop).

[BoSNiaN]

1)What made you replace the N80 valve and how much did it cost?

2)Did you find the issue for the shuttering acceleration on WOT?

I am having the exact same issue, only when accelerating really fast [headbang]

[dba4]

similar issue, if i accellerate in 6th at WOT i get a shutter/hesitation. i was under the impression that it could be the cam/follower/fuel pump issue causing this.

[Operator]

With the codes, the N80 valves was one of the suggested fixes. The valve was pretty cheap if I remember correctly, so it's not a bad idea to replace it just for peace of mind.

As for finding the issue. All I know is, after changing out the 2 items above, the car ran fine.

[digitalAUDI]

i had a similar issue, and my mechanic said it was plugs and coils as well. He also had a code for the fuel pressure sensor, not sure if you got that one.

[dba4]

i recently had my coils replaced under the audi recall, and had the plugs shanged at the same time, maybe i will try the n80 valve and see if that makes a difference?

[BoSNiaN]

I'll be pulling my codes today but:

1)plus changed a month ago, 4 x brand new NGK BK6RE
2)follower changed in july (fuel pump and cam lobe looked fine)
3)got a new gas cap (R8) over the summer

Must be coils or the N80 thing (where is it and what does it do?)....