S4 stage 2 APR tune fluttering issue

[ATP S4]

I recently purchased an s4 with 99k on it and have had a weird problem upon acceleration. When I go full throttle in any gear around 3,000-4,500 the engine starts to flutter and the car shakes. This problem doesn't happen when I rev it in neutral. The previous owner told me it was the tune causing the fluttering but I'm losing a lot of power when it happens. Could this be the tune? Or is there another problem I'm going to need to deal with? Still kind of new to the car scene so I'm not 100% sure what I'm dealing with.

[Corradovolksb]

Sounds like you need to regap your spark plugs to .020in. If your running over 16psi the cylinder pressure may be blowing out your spark causing misfires and lack of power. Do you have any fault codes stored? What boost are you seeing when this happens?

[goalieman24]

+1 for codes.

Any records of the previous owner changing spark plugs, coilpacks, or ICM's? I'd bet it's likely one of those things before suspecting the tune.

[f4m0u5]

Sounds like you need to regap your spark plugs to .020in. If your running over 16psi the cylinder pressure may be blowing out your spark causing misfires and lack of power. Do you have any fault codes stored? What boost are you seeing when this happens?

.020? I run .029 with 0 problems on my stage 2 car

[Timtheguru]

Throttle body alignment, and for the love of all that is holy, change out that FPR.

[ATP S4]

Thanks for the input. Previous owner gave me almost nothing to work with. I'm guessing I'm going to have to go through and make sure every part is working right. I'll try regapping my spark plugs first. Will any FPR work or is there a certain one I should get?

I don't have boost gauges so I've got no clue what I'm running

[Timtheguru]

Get the $30 Bosch FPR from rockauto.com.. you'll have to drill down to the car on their site. Also, you should pressure test. Google pressure test b5s4

[vavJETTAw36]

I would just change plugs If you don't know history


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[ATP S4]

So I just went ahead and replaced the spark plugs and gapped them at 0.028 and the fluttering has gotten A LOT worse and it's knocking a lot more at idle. I have no idea how this made the problem worse but it did

[AvantGuard]

Check your throttle body boot for leaks.

[Timtheguru]

Did you torque each spark plug to 22 ft/lbs? If you did it "hand tight" then you probably have a bound up washer or something. You should pressure test.

[goalieman24]

What plugs?
Take a video of your tach to show this "fluttering".
Check for codes yet?

[ATP S4]

Hey sorry it took so long to respond. The issue ended up being the coil packs. I just purchased a full set with ngk's from ECS, put them in and now it's running nice and smooth like it should. Thanks for all the feedback guys