v8 jdm

hi guys i have a 03 sti jdm iam not sure if this is how they all are but if iam in 5th or 6th gear doing about 80mph if i put my foot down it feels like its holding back feels like its not goin anywere as if the boost comes goes comes goes every second its hard to explain, but if i keep the revs hight and drop down a gear its fine, on the roads its fine also. if i went from 1st to 6th with my foot down to 120mph its fine, only happens if my cruising and put my foot flat to the floor, just gets on my nervs when you get someone in a nova gte at the side of you on motoway and they pull away, i then have to start droping gear after gear to catch up anyone help?

weeebell

iTrader: (1)

Maf sensor. My 1999 turbo was EXACTLY the same. Goes ok if you 'tickle' the throttle or nail it, but if your foots anywhere near half, its like either too much fuel of too much air and just goes flat.

v8 jdm

hi thanks for the info, were is the maf sensor, iam geting it re-maped soon would that sort the problem out thanks

weeebell

iTrader: (1)

Depending where you disconect it from, it will either be connected to your airbox or on the hose coming from the airbox. It will have a multiplug on it.

v8 jdm

oh thats what it is. i have a cheap after market air filter on would that be why? how much are thr sensors?

dynamix

iTrader: (3)

overboost

v8 jdm

hi do you think its over boosting? thats what i have just been told by a garage when i just phoned them. have you had this problem before?

dynamix

iTrader: (3)

Very common at this time of year.

Have you decatted it and not had it mapped?

v8 jdm

no its not been de-catted or mapped yet but has a cold air filter and 4" centre section and back box, my centre pipe dont have a catt as its the jdm spec.

dynamix

iTrader: (3)

the 4 inch centre section and back box are causing a lower back pressure than the factoy have mapped it for. This is worst in 5th and 6th gear as the load is larger.

The boost control is therefore not expecting the boost to rise as rapidly as it does and it feels hesitant as it hits boost target and overboosts then tries hard to reign itself in.

Get it mapped would be my advice.

or remove the exhaust mods

or put up with it (it is not doing it good though if it is overboosting a lot)

Have you got a boost gauge?

v8 jdm

hi no no boost gauge. if i put my old exhaust back on would i lose any power? thanks for your replys mate.

dynamix

iTrader: (3)

yes - you would lose power because it wouldnt be overboosting then.

mapping is the way forward

v8 jdm

just had the boost sorted, but its still doing the same thing, had it on a diagnostics nothing shows up on it, the guy said it could be the coils???? or maf sensor?????

dynamix

iTrader: (3)

The boost obviously isnt sorted then.

As was said on your other thread, the mapping needs to be done right to get rid of this.

saiklon

I don't think it is boost cut. Boost cut is very violent and the car cuts off all power till manifold pressure is negative (basically cuts off power till you get off the accelerator).

I suggest you try replacing the MAF as was suggested by weeebell above.

Jolly Green Monster

iTrader: (4)

surge?