2000 A4 1.8t(ATW) Miss under WOT/Boost
 

Picked this car up over a month ago. Higher miles, 202k but it has every service record from the first owner. Car is APR tuned and has an APR exhaust. It has developed a strong miss or buck when building boost at WOT. Since this has started the car feels slow. Turbo does not spool as fast and as hard as before. No CEL on. Started after washing the car one day, CEL did trip and cyl 1 was misfiring. Replaced coil pack and new set of plugs. BKR6E's? Seemed better and then the problem came back just the same. Any ideas on what this could be considering i have no codes to point me in a direction.

Generally with a chipped car it's a good idea to go with the next heat range cooler spark plug - BKR7E - and make sure they are gapped properly (0.028").

When you say the problem came back the same, are you still getting a misfire on cylinder 1?

I also hear Ford Motorcraft plugs are great for boosted cars. I know a lot of guys that run copper plugs. The only downside is that they foul much faster so it's a good idea to change them every 5k miles.

What happened was I washed the car and it seemed to start then. Misfired a few times and the CEL flashed at me. It went away and seemed to be fine for a week or so when i noticed small misses more and more but no CEL. I scanned it to see what codes were stored and it came up as cyl 1 misfire. I was told sometimes VAG sees cyl 1 as cyl 4 in relation to actual cyl numbering. Anyway replaced that coil pack and plugs and it seemed only slightly better. Its worse and worse by the day and worse the warmer it is. Every time no matter how many or how hard the stutters are i cant get a code to show. Could it be something like a bad FPR or boost leaks?

Exact same issue here
 

I'm new here, but I have the exact same issue. 2000 A4 180kmi. I hit a large puddle and then like 10 minutes later I am going to pass someone hit 3.5k-4k at WOT and wham, hard decel.

I checked everything when I got home, specifically water in the intake track or a wet sensor, but nothing.

I just got a set of new plugs, but haven't swapped them in yet. My vagcom is on the way. My CEL came on a few weeks ago.

I am assuming it is something electrical, but I would love to hear any suggestions. I have also noticed the occasional throttle cut in the mornings (it was as if I had my foot on the brake and the computer did the throttle override safety thing)

WOT bucking in a turbo car, usually is the wastegate actuator. it sticks.

now the downside to our cars is we dont have a boost gauge, if you have one installed or went out and installed one(even if its just a cheap one to diagnose your problem)you'll notice your boost also doesn't hold. at WOT, it will start to leak. generally when the actuator acts up it sticks closed but doesn't close all the way and causes said leak.