02sslayer

iTrader: (4)

i have asked this before but wana try it again and see if i can get some help.
car is throwing flashing code PO300. this happens at WOT around 4k rpm and above. car runs very rugh at this time and after i let of the gas for about another minute. i changed plugs and i did like 10 WOT pulls all the way to redline and it ran great! could not get it to run shitty or throw code no matter how hard i try. take car on freeway little bit later and it starts right up doing the same crap. so far i have:
changed plugs
wires
tested coils
fixed a couple vacume leaks
took intake mani(fast 90) apart.
checked for broken valve springs

intake is still off car and none of the other things fixed it either.

well now im replacing my topend, kinda got a wild hair and decided to remod my car(btw car has heads and large cam now) while i fix the problem. so im just kinda wanting to know what you guys think. also i figure i might as well switch out cam position sensor, crank sensor and maybe 02 sensors? so what else might be worth replacing? those 3 are the only sensors i can think of. and if it turns out to be something wrong in the heads or cylinders i might find out. the intake runners on the heads looked all to be fairly clean. anyway, all you input is welcomed and i thankyou for it.

02sslayer

iTrader: (4)

anybody?

02sslayer

iTrader: (4)

same results as last time..no one has a clue lol. yes i treid several searches, just never found one with issue like mine.

3rdCoastPowerSports

iTrader: (5)

If you still have the heads on the motor, run a compression test followed by a leak down test to pinpoint your problem. Are you data logging when the misses occur? If so look at your individual misfire counter on your PIDS. Should give you a place to start.

99Bluz28

iTrader: (35)

Id say either the Crank PS or Cam PS, more likely the crank.

02sslayer

iTrader: (4)

i agree on the testing, heads are coming off soon. ok i have heard of data logging but to be honest....i have no idea what that is. i feel like a newb and i should probly know this. so that would be a no on that lol.


you know, i really hope your right. this would be a great time to change them out.

thanks for input guys, i really appreciate it.

there is one other thing idk if this could be related in anyway. down the road after i got my h/c tune i installed a stock fast 90/90. a guy in my regional forum made a suggestion(seems to be pretty knowledgable)to make the car run better until my retune. he said that i should(dont remember exactly now, it was a couple years ago)undo the iac sensor then do something like turn the key on three times or something close to that. so i did it and it dident seem to help really. 2-4 weeks went by and it ran ok, then all of a sudden i got on it one day and there ya go flashing PO300 at high rpm ever since. treid a few things to fix it but have been avoiding it.