jakeyb2525

Hi, my mate has just bought a 1995 sti, and under any more than 0.5 bar of boost holds back and we get the hitting a brick wall loss of power, we have changed the:

coil packs
maf
boost control unit
fitted new plugs
changed the ecu to a z4 chipped
by passed the gauges and electronic boost control

with no joy!!!!!!!

we dont really know what else to try, could it be the actuator on the turbo..?

any help would be great.....cheers

m@t STImulation

iTrader: (3)

def the actuator needs adjusting loosen it 1/2 at a time till it runs corectly

jakeyb2525

cheers mate will try it tomoz, if that is loosened off will it still have the same power when running at 1 bar ....? also is this not the same as turning the boost down on the boost controller ... ..?

dan83590

Why not try a standard STI ecu? The Z4 is for a 95-96 WRX chipped or not. Sounds like it may be in limp mode. Are there any codes stored? Do a ECU diagnostic by connecting the connecters beneath the steering column and go from there.

Looky here Frequently Asked Questions ECU Reset

jakeyb2525

Hi we have the standard ecu, we only tried the z4 because it was chipped and thought it might have been a fuel cut off problem, a friend is coming round tomoz to check for fault codes, not 100% but got a strong feeling its not ecu as it does the same with the standard ecu in.

dan83590

Granted, but the STI ecu will be set up differently as the timing is slightly different on STI's, my ECU comment wasn't 100% relevant.

Check the codes and post back matey.

jakeyb2525

Will do mate...is it common for an actuator to pack up..?

Broxi

iTrader: (11)

what plugs were used, and what did you gap them to?

I have a Chipped Z4 in my 93 RA... with a 2.5 enging in the car. and it runs spot on.. also run spot on with a 2.0

I am A Mechanic.. and the car has been on the dyno and confirmed it is running good.

I would suggest the Fuel pump.

Also incorrect plug gap has also been known to cause this.

midloscooby

iTrader: (2)

pretty sure your actuator will be naffed chap.

Disconnect the vacuum hose from the actuator and connect a foot pump to it,, if when you pump you hear hissing or can feel air escaping from the actuator ,the diafram will be gone..

this causee,s the kind of problems you are experiencing.

very common on evo,s but not too sure on scoobys

hope this can help you

regards sam

dan83590

That's just good fortune really isn't it. You have an ECU delivering enough fuel for a 2.0l and the block sucking in 2.5l of air. Just because you got lucky doesn't mean every other set-up will work. Poor advice that matey.

Broxi

iTrader: (11)

I am not going to be drawn into an Argument with you or any one else inc mappers on this...

But it is My opinion to which i am entitled that Fuel is added in proportion to the amount of air being added, if you are to add more air then more fuel is required.

As long as you have a working MAF & O2 Sensor then the maf and 02 sensor will work together to adjust the amount of fuel given to the engine.

This is as i already said relevant to the amount of air going in.. this makes no difference if it is a 1.0 or a 5.0

If you run on a MAP base then it is a different kettle of fish, as the ECU will not adjust due to not having a maff to measure the air flow going into the engine.

IMO adding a FMIC or increasing the capacity should have no great effect, on a car that has a properly functioning Maff & O2 Sensor.

I have run 3 of my own Scoobs with FMIC, full Decat, Induction kit etc etc as have a Number of my friends all Un mapped, and when we do rolling road day's all of the cars are running well.

If you want to make the most of your modifications and up the boost signifiantly then yes you would want to get it mapped.

As i Said all in My opinion to which i am entitled.

johngoulding

iTrader: (7)

would a bad 02 sensor cause 0.5 bar of boost or for that matter would a bad 02 sensor cause bad boost also ( limp mode )