02 sti runnin bad at top end PROBLEM SOLVED!!!

Hi all, I have a problem with my 2002 sti impreza JDM.

The problem is that the car seems to "miss" under hard acceleration but only in the higher gears and when boost pressure is in the higher end. This only happens if the foot is to the floor. If I accelerate gradually there is no problem.

What i have tried so far.... New set of plugs- NGK 6b's
Air Flow Meter
The car had been de-cat'ed so I bought a cat and fitted it.
Fitted a new Warlbro fuel pump, &
Bought a boost solenoid, (second hand from a breaker)

None of these solved the problem or made any difference.

I brought it to main dealer, Finnegans, and they road tested it with diagnostics connected............Not reading any faults or problems.

Also brought it to another guy that a friend reccomended, drove it again while connected to diagnostiss.....again no problems registering!

I have since fitted the Defi STi Genome gagues with a boost gague. This is now showing me that just as the problem (the "miss" or "power failure")starts, the boost guage shoots up well beyond 1 bar and even beyond 1.5 bar.

To my knowledge the car has nover had any tuning carried out or boost controller fitted.

I think I have all the details in there now.
Any suggestions or solutions would be greatly appreciated.



PROBLEM........... Cracked turbo housing!

Found by STI Tuning.

Re: 02 sti runnin bad at top end

i'd say the car is getting fuel cut causing knock which is not good.

i would recommend getting a boost controller and set it at 1 bar or get the car remapped to suit what you want from it.

Re: 02 sti runnin bad at top end

Should this show up on the computer when driven while connected?

Subaru dealer said there were no coming from the Knock sensor and the other lad said the fueling system was reading as ok!?

Re: 02 sti runnin bad at top end

Would have thought knock would be picked up by a diagnostic system too?

I had a similar problem with my car that only came into it under full throttle, turned out it was the plug leads that needed replacing. Problem solved.

Re: 02 sti runnin bad at top end

[quote author=STi Brian link=topic=22534.msg270869#msg270869 date=1270130317]
Would have thought knock would be picked up by a diagnostic system too?

I had a similar problem with my car that only came into it under full throttle, turned out it was the plug leads that needed replacing. Problem solved.
[/quote]

Its individval coil packs on each plug eliminating the plug leads. Have had the coil packs out to examine them but could see no cracks or damage on the casings.

Re: 02 sti runnin bad at top end

Your car sounds like its over-boosting and the ecu is cutting the fuel, having the same trouble with my motor but its my turbo thats causing the problem, maybe have the turbo checked just to be on the safe side

Re: 02 sti runnin bad at top end

[quote author=B4_RSK link=topic=22534.msg270887#msg270887 date=1270133871]
Your car sounds like its over-boosting and the ecu is cutting the fuel, having the same trouble with my motor but its my turbo thats causing the problem, maybe have the turbo checked just to be on the safe side
[/quote]

Its a complete pain, nearly afraid to overtake.

When you say get the turbo checked, in what way can it be checked? Could the waste gate be a problem?

Re: 02 sti runnin bad at top end

The turbo could be free wheeling,what turbo is it a vf??,is the boost solenoid ok and make sure the actuator is working correct.

Re: 02 sti runnin bad at top end

Is the vacum piping plumed the correct way on turbo? if i can remember correctly, as ive no car to look at, basically you should have a vacum pipe coming off comp housing, then it is T pieced, one vacum goes to actuator and other to solenoid. before the T PIECE, there should be a restrictor olive in piping from T piece back to Comp housing.
It definitly sounds like its over boosting and fuel cutting

Re: 02 sti runnin bad at top end

[quote author=skinny-controller link=topic=22534.msg270951#msg270951 date=1270150458]
The turbo could be free wheeling,what turbo is it a vf??,is the boost solenoid ok and make sure the actuator is working correct.
[/quote]

As far as I know its the stock turbo. Sorry dont know any part no. for it or anything. Can the wastegate be tested in some way without replacing it with a different one?

Re: 02 sti runnin bad at top end

[quote author=KENC link=topic=22534.msg270960#msg270960 date=1270151351]
Is the vacum piping plumed the correct way on turbo? if i can remember correctly, as ive no car to look at, basically you should have a vacum pipe coming off comp housing, then it is T pieced, one vacum goes to actuator and other to solenoid. before the T PIECE, there should be a restrictor olive in piping from T piece back to Comp housing.
It definitly sounds like its over boosting and fuel cutting
[/quote]

Im pretty sure that the vacuum pipes are in that order, will check it out tomorrow and check for the restrictor pill.

Re: 02 sti runnin bad at top end

Thanks to all for all the help so far.

I'll have a look tomorrow and try to answer all your questions with proper info!

Re: 02 sti runnin bad at top end

maybe try the boost controler and maybe a fuel pressure regulator and uprated fuel pump!!!

Re: 02 sti runnin bad at top end

have that same type of problem sometimes on mine....
mine is mapped to 1.5 bar(i think) but on hard driving,its boosting to nearly 2 bar...
but a certain mapper maintains that it is fine!!!!

Re: 02 sti runnin bad at top end

have you a 20g turbo marko? think 20g are have a surge issue, and was there not something on newerage vf turbos needed a bit of porting on waste gate?
Tom with the Rb320 was having the same problem with his and was told tho get a 3port solenoid and got mapped again and sorted.. .5 of a spike seems to me to be a bit xtreme???

Re: 02 sti runnin bad at top end

[quote author=STiBug link=topic=22534.msg270895#msg270895 date=1270138311]
[quote author=B4_RSK link=topic=22534.msg270887#msg270887 date=1270133871]
Your car sounds like its over-boosting and the ecu is cutting the fuel, having the same trouble with my motor but its my turbo thats causing the problem, maybe have the turbo checked just to be on the safe side
[/quote]

Its a complete pain, nearly afraid to overtake.

When you say get the turbo checked, in what way can it be checked? Could the waste gate be a problem?
[/quote]

Yeah i know how you feel, not sure what way it can be checked but maybe drop it into one of the traders and have them look it over

Re: 02 sti runnin bad at top end

[quote author=KENC link=topic=22534.msg271052#msg271052 date=1270158678]
have you a 20g turbo marko? think 20g are have a surge issue, and was there not something on newerage vf turbos needed a bit of porting on waste gate?
Tom with the Rb320 was having the same problem with his and was told tho get a 3port solenoid and got mapped again and sorted.. .5 of a spike seems to me to be a bit xtreme???
[/quote]

md321T ken!!!!
i bought a new boost solenoid recently so goin to try that!!!

Re: 02 sti runnin bad at top end

Was it the perrin solenoid you got rid of mark?

Re: 02 sti runnin bad at top end

[quote author=Sweetcakes link=topic=22534.msg271186#msg271186 date=1270237859]
Was it the perrin solenoid you got rid of mark?
[/quote]

not yet robbie but i suspect the bcs!!!

Re: 02 sti runnin bad at top end

Is it a 3port?