Why does the car miss above 15 psi

[CBgst]

I've been helping a buddy with his 90tsi awd and we are having some problems. The car misses above 15 psi anything lower and it's fine. I know this is not fuel cut. His mods are
2nd gen. ported mani
16g
mbc
K & N w/ hacked air can
ported evo O2
3 in. downpipe turned down
550s
walbro 255
afpr
afc
gauges
I think that is it.
We put in new plugs( ngk bpr6es) gapped to specs under the the hood. We changed the plug wires( 2nd set this week). We did a boost leak test and there is a small boost leak. I don't think that's the problem anyway because the car runs fine until about 5500 rpms then it starts to studder. The car does still pull and rev to redline though. It feels like a cylinder starts to miss. Any ideas would be great this is driving me nuts trying to figure this out.

 

[Thalomos]

What did you gap the plugs too? Try gapping them at .030

 

[GBabyTSI]

thats what we gaped them at but still the same its my car

 

[GRNDSM]

What plug wires are you using?

Leon
RR

 

[97GSXAT]

I had the same problem, only it was when I was hitting anything over 5 psi the car would misfire and studder pulling a CEL which turned out to be a misfire in cyl. 2. I changed the plug wires (after changing the plug to find that wasn't the problem) and now she runs good as new, I am using bosch wires btw, but many other better brands out there.

 

[fastdsm1]

I had the same problem and i replaced the wires & plugs but i still had the same problems happening.....missfireing at high rpm & boost.!!!! so i went to the local junkyard and got 3 ignitioncoils and as soon as i replaced the first coil and took it for a testdrive i automatically noticed the studder was gone and at high rpm & boost the tranny shifted properly.......(during the high rpm & boost runs the car started missfireing above 4700rpm all the way to redline and the tranny wouldnt want to shift ------by that i mean it went through L,2,D and get stuck in drive even if the overdrive button was activated.eventually it shifts but late......hope this helps.......................

 

[Brandon92DSM]

coil pack.

 

[GBabyTSI]

i am using ngk plugs and i am going to try a new coil pack i will let yall know whats up

 

[umiami80]

Gap the plugs at .20, works perfectly ANd I had the EXACT same problem as you, sounds extreme? Try it and get back to me, you'll see.

 

[zac83]

+pressure = gap resistance... if the resistance gets TOO high, you'll fry your plugs due to blowout of the surface material AND you'll run crazy amounts of voltage though thoes wires. try gapping your plugs lower for an overall lower resistance. Just a note: if your running MSD and 'large gap', expect to change your wires fairly often... msd works thoes things out like you wouldnt believe. new wires will help since they can deliver the power since they dont have carbon burn of the old wires.

also you could be burping boost somewhere and getting a rich misfire from a lack of air....

somehow my car runs perfect with a .40 gap on ac delco plugs/stock ignition/wire on a JDM motor, my buddy almost crapped himself when i told him what i gapped at.