hey everyone!

my tuner and i were tuning my car a few days ago and ran in to a problem that prevented us from moving forward. i went from a mbc to a grimmspeed 3port and got rid of my cobb accessport for an open source. while we were logging, i went to do a 3rd gear pull and as soon as i started going into boost it felt like my car was stuttering/bumpy/laggy(best ways to describe it).

my first thought was "uh oh clutch is slipping" but then i have felt a slipping clutch and it didnt feel that way. usually when the clutch is slipped, it doesnt grab again and slip then grab then slip.

a friend then told me that since you now have a 3port your holding boost alot better and that maybe your spark is blowing out. so i got new spark plugs and the problem still didnt go away.

next i thought maybe my 3port was hooked up wrong or theres some sort of boost leak however my tuner said that my logs and boost curves look perfect and its holding boost excellent.

also just an observation i am not getting any knock when this happens. im almost positive its my plugs i even double checked the gaps and tried running them at factory specs (.020) and i also tried closing them a bit to see if it would prevent the spark from getting blown out.

my car is moderately modified.

fpred
800cc injectors
ams intercooler
ams intake
ets uicp/licp
grimmspeed 3 port
perrin turbo back exhaust
test pipe
walbro 255
agency power bov
act racing clutch

thats everything related to engine mods i can think of.

as always guys any help is appreciated! thanks

 

Check the fuel pump relay..... Known issue causing a lean condition. Without a wideband you may not see it go lean.

I'd recommend not beating on it or going WOT until you have the AFR checked and the relay is good.

That's step 1 if I were you.

 

Are you running a wideband to log AFR? If not, you shouldn't be tuning anything until you know what your AFRs look like. It sounds to me like a fuel related issue.

 

Thanks for the replies. Yes I do have a wideband installed. As soon as this started happening we stopped tuning.

Also the cause of this was a bad fuel pump relay. I swapped out the high beam with the pump relay and now I have smooth WOT! My Afr looks good. I guess that when it was running lean it was doing it in short bursts just fast enough that my wideband couldn't register it. Everything seems to be working now. Thanks for the help guys!