BoostFrenzy

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

cruiser

How are your grounds ?

MazdaSpeed93

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.

quicksilver_rx7

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

XSTransAm

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

willjs7

iTrader: (1)

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

kevinbtz

iTrader: (4)

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

BoostFrenzy

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?

kevinbtz

iTrader: (4)

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

kevinbtz

iTrader: (4)

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

BoostFrenzy

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

kevinbtz

iTrader: (4)

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

BoostFrenzy

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

cruiser

Redo your grounds.

tcb100

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