Golf 1.8t AUM engine. Misfiring P0300/P0304

[atomicgolf]

Hi Guys my golf 1.8t has developed a misfire but only at full throttle and intermittently although it's more often than not now.

Its only when I gun the throttle, it starts, idles and pulls Ok upto 1/2 3/4 throttle then it starts to judder/misfire. CEL light flashes and
it limps with not as much power although its still smooth.
I code read it tonight and got;
16684 Random multiple missfire P0300
and:
16688 cylinder 4 missfire P0304

I'm not sure where to start although I'm sure the plugs haven't been changed for a while, other than that i'm not sure where to start. Does anyone have any pointers?

[Flash2]

Since your misfire is only happening when you gun the throttle, It might be a fuel pressure problem. The freeze frame data recorded when the DTC is triggered might give you a clue. Take a look and see what sort of figures have been recorded in the fuel trims.

Jim.

[atomicgolf]

Hi Jim,
Thanks for your input. That may be a possibility and will be my next area of focus if the electrics turn out not to be the issue.
Today I chucked some new plugs in and swapped the cylinder 4 and 2's coil packs around and cleared the previous codes. I took it for a run and could feel the odd misfire even at lowish throttle. So I drove it 5 miles gunned it and it started the misfire again and going into limp mode. I code read it again and now it's showing a misfire on cylinder 2. So the fault is following the coil pack. I will get a new pack in tomorrow and test it again.
Fingers crossed!

[atomicgolf]

Sorted, It was coil pack number 4, the fault proved by moving to number 2. The car runs great now and holds boost nicely.

Gotta love the VAG-COM what a useful tool!