zafar51

hi all,
I have a 93 wrx, with a uprated walbro fuel pump, and just basic mods like air filter,dv, full decat, at about 4500 revs i get like a sharp jerk and the check engine light flags up, ive tried reading the code but nothing, ive tried the w6 and z4 ecu and happens with both and gone back to the original recirc valve and still no luck, is this fuel cut or can it be something else? is there anything i can try to cure the prob??should i go bk to the original fuel pump?any ideas plz guys??zaf

Maz

iTrader: (34)

Sounds like it's overboosting. In cold weather it will be prone to doing this especially with the mods you have.

zafar51

thx for ur reply,if it is overboost,can i get around it somehow?ive got a turbo smart maunual boost tee, if i turn it right down will that work?

Maz

iTrader: (34)

Manual boost T, hmm sounds like a bleed valve. Quite a crude method of boost control. I would close it completely as that may be the cause of the overboost. If that doesn't work I would advise a specialist to have a quick look over. A simple hooking up of a boost gauge will reveal how much boost you're running and wether or not that is causing the fuel cut.

Maz

LegacySTi

iTrader: (13)

yes its fuel cut from overboost..

map for your mods set up is most sensible move to make..

zafar51

maz, the manual boost tee is not in the car yet,just asked if this mite cure the prob if i do put it in and keep it turned down?, and the boost gauge reads about 0.7/0.8bar when this happens

Marx Mcrae

iTrader: (4)

Definatly sounds like the fuel cut.
The safest thing to do would be to get a scooby ECU

Maz

iTrader: (34)

Boost is about right for your car at 0.7/0.8 bar. It certainly shouldn't be cutting out at that pressure. I think the best course of action is to get a rolling road check up. It's the safest way of checking what the engine is doing. All the parameters can be checked i.e boost, fuelling and any other issues that may be there. It should cost between £60 to a £100 depending on how long your car is on but should give you a definitive answer.

zafar51

can it have anything to do with the uprated fuel pump?is it worth me cleaning out the boost solinoid, and if no luck with that then trying out the boost tee, just to make sure if it is definatly boost related?

myblackwrx

iTrader: (1)

Oveboost doesn't (shouldn't) bring the CEL on.

I used to have overboost on my 93wrx with the standard ecu,then changed it for a z4 and it was fine.

Boost Targets & Fuel-Cut Limits
WRX/STi Saloon ECU's 2C, U8, W6, W9 - As above, 11.47psi held to redline. Fuel-cut 14.57psi
WRX (1995/96) ECU Z4 - 12.71psi, dropping to 11.78psi @ 6600rpm. Fuel-cut 15.65psi.

not convinced it's fuel cut tbh

zafar51

(myblackwrx), hi mate, the cel definatly comes on, everytime it happens, but when i try and read the code it never comes up, if its not the overboost is it down to spark plugs or coilpacks?
p.s thx for ur reply i know u have helped me out in the past before

myblackwrx

iTrader: (1)

Can you go above 4500rpm?
Does the speedo stop working?
imo if there was a problem with coilpacks/plugs you most probably (not definately) get a problem when coming on boost.

As stated by Einstein RA you are getting a problem at standard boost level which is not fuel cut (post 10 show the levels) so i would go with his suggestion of a rolling road session to find out whats going on (as it will be cheaper then spending money on plugs/colipacks and finding it doesn't cure the problem)

zafar51

i havnt really pushed the car so didnt try and go above 4500rpm, speedo doesnt stop working though,the prob is defo only on boost, if it was a prob with the coil/and or spark plugs would the cel light flag up? (sorry for the late reply)

404BHP

Take your coil packs off and look to see if the ends are cracked under the rubber boot...Had this with mine and it was coils doing it...Also check plugs while you are there..

zafar51

thx for that mate ill try it on the wkend and c how it goes..