sjice

iTrader: (1)

Alright, so when i downshift my car into 5th on the highway and step on it.. it hits about 100 and then jolts me back in my seat and acts if i hit a limiter and the speed decreases.. the check engine light then turns on and my cruise control light starts flashing.

i posted this problem before, because i thought it was something to do with the MAF sensor on my Injen intake, i removed the injen intake a few days ago, now im running stock airbox without a silencer.. but i guess it didn't solve the problem. I was wondering if anyone could help me out or shoot me some advice..

04 STi

thanks

wm07

iTrader: (2)

Catless? sounds like overboost to me.

sjice

iTrader: (1)

yea im catless... turboback .. helix dp with borla catback

overboost? so how would i deal with it?

wm07

iTrader: (2)

some people enlarged the wastegate in their turbo, i wouldn't go that route.
I am running a high flow cat and do not have any issue.
I remember some people put their stock catback on until they get a tune.
not sure if Cobb AP will fix that problem though, but I am sure some kind of engine management can fix that too. (the EM that raises the boost limit)

Me&05WRX

iTrader: (2)

Boost creep? Isn't that an issue for 04-05 STi's when having a TBE? I'm just throwing things up in the air in the effort of helping... good luck!

Bullhonkie

Yeah sounds like boost creep. Your wastegate can't bypass exhaust gases fast enough and as a result you keep building boost when it should be leveling or tapering off. The ECU eventually freaks out because it sees too much boost and cuts fuel which is usually felt as an abrupt loss of power.

Do you have any engine management? I think it can be minimized to an extent with a good tune. Problem may persist though because it's a physical flow limitation with the wastegate itself. Seems to be a lot less common with catted downpipes since they're not quite as free flowing.

STi-owns-evo

iTrader: (4)

Do you have a boost guage? If so, I'd have a friend watch it while you're driving, since I'm sure watching it while going over 100 isn't exactly the safest thing to do.

Emsraumajunke

My friends 02 and my other friends 03 has done that before minus the cruise control light. His problem was wastegate overload atleast thats the the Magic box said. My sugestion next time it happens stop by autozone have them plug the code checker thing in and see what the codes showing. But m firends fixed it buy getting an Acess port. Once the got that pt on the problem went away.
Hopefully this will help.

pj21086

iTrader: (24)

I have an accessport and I'm tuned for 17.5 psi but i have boost creep and sometimes boost up to 21psi. You wont hit fuel cut with it though but you will still have boost creep.