Car has intake/downpipe, boost pattern is good, pulls nice and hard to 6000 but then has a very very slight stutter on it's way to redline, tach pauses in places for a MILLISECOND and power delivery isn't right, no backfires/noises from engine or exhaust

plugs have 1000 miles on em, wires about 50 miles, replaced many vac lines, possible i fouled the plugs already!? (stock ecu), runs/drives absolutely perfect otherwise, good idle, however vac just a smidge on the low side @ 750 (~14 inches)

maybe just take out plugs and clean them?

this SHOULD be unrelated but problem arose when i switched out the OEM O2 sensor for a bosch universal and replaced the purge valve throwing code (cel #40), no cels exist and i've checked and rechecked my vac line connections MULTIPLE times

 

How are your grounds ?

 

I changed my plugs and wires and found out that it did nothing for that. My car does that too, but does it from about 6k-6500rpms then pulls again. I posted a long time ago and people told me that i need to get a new ignition so i can get hotter sparks to the plugs. I plan on getting either HKS Twin-Power ignition or the XS engineering ignition. I guess this problem isnt all that unusual.

 

^ I would have to agree. Sounds either like an ignition problem or a ground problem (the former being the most predominant cause).

 

i had horrible breakup/misfire problems whenever the car was in boost. I must have changed my plugs 5 times, got new wires. pulled and tested and retested the coils, checked the timing, played with the fueling. Nothing ever helped.

Then I bought a jacobs fc1000 ignition amp, no more misfires and i am boosting 17psi with no problems. Only thing is now i have like 4 sets of plugs with under 1000 miles on each of them.... Guess i dont gotta buy plugs for a while :P

 

mine did the same thing, i got an aftermarket ECU and it went away

 

In my 1st gen I was having the same problem, what I did to finaly fix it was put a 2 1/2 restrictor in my 3" exaust..... I think it was hitting some thing like fuel cut because of boost creap. At first I thought it was ignition related because of the symptoms ( high rpm breakup). good luck

 

i tested the resistance in the leading coil, all is good, checked the plugs and they're nice and tan (cleaned them anyway), still kinda there i dunno what's goin on :/

might be related the low vacuum i pull at idle (~14 inches) maybe a leak somewhere?

 

just make a sheet metal restricter plate and put inbetween your downpipe and midpipe

 

did it start right around the time your put the intake and or down pipe on?

 

no, it started when i replaced the bad purge valve and installed a bosch universal o2 sensor

 

you say that no cel exists... does that mean you reset your ecu? If you haven't I would definatly give it a shot.

 

i grounded TEN and GND, light turns off, no codes stored, no cels.

 

Redo your grounds.

 

Throw money at the problem. Buy a twinpower. It cures any high rpm break-up.