Hi. After 2 weeks of isolation and changing parts im stuck now.

Subaru impreza sti gc8 v2 1996.
Mods as I now of as only just brought it.
front mount intercooler.
Vf22 turbo
Lightened flywheel
Light pully wheels
Brembo brakes
6k ecu which I am changing soon.

I was first having this problem when cold but now does it when hot.

The car loses power it hesitates 1 2 3 gears when driven hard but worse in 1st and 2nd. This what happens when im accelerating hard to 7k change gear to 2nd the car as if it loses power lift of accelerator back on then full power is back then it loses power instantaly again. It eventually clears. Then is all ok again.


But now is doing it driving normal aswell ive noticed it does it now around 2500 - 3000 rpm. But not as harsh. Again like it losing power. Once you rev it it goes away.

Ive have changed maf, o2 sensor, coil packs. Spark plugs and regaped as a few people had said the plugs could be blowing out on boost.

So the question is any ideas what it is and what else to do next guys im lost now.

Cheers Phil

 

Might be worth cleaning the boost solenoid, they can get clogged up. Also, checking for boost leaks is always worthwhile.
If there was a time when it was running okay, and then developed the problem, try to figure out what changed. Hopefully it'll be something simple.

 

Hi thanks for the reply. Ive also changed that also forgot to ad that to the list. With boost leaks ive gone round every hose I can see loosed them and re tighted up and checked for cracks and splits.

I have only just had it be 4 weeks ago now. The guy who I brought it off told me it was doing but never done it often. which it didnt but now its all the time and getting worse. 😟

Thanks Phil

 

If it's not running as well as it was then you'd have thought that something must have changed...
Having said that, you have mentioned that it has a front mount intercooler. If it hasn't been mapped for this, then that could cause issues. I'm not sure what turbo is standard on that car (I thought it was a TD05?), but if the VF22 isn't standard, then that could cause problems also. What's the boost running at? From memory it should only be around 0.95bar (I may be wrong), if it's much higher then that would also lead to problems.

 

defenitley needs a map, all that extra air from the fmic ecu wont be happy.also as above vf22 is not standard tub,i have a jdm MY96 and has a td05 from new.

 

Map it..

 

No. Not yet.
If it was running okay when you first bought it, then you have a problem that you need to eliminate before you map it. If you map it with an air leak or whatever is causing the running issues, then you'll just have to map it again when you DO find the problem.
When the car loses power, does it feel like the brakes have jammed on? Or is it more like a fluctuation in power (more gradual)?

 

Agree it needs mapping. The boost I have no idea as there isnt a boost gauge I have ordered on hopfully should be here tomorrow .this is the problem as it was fine when first had the car then after around 500 miles she start playing up. Gradually getting worse. When it looses power its not like slaming brakes on it like it run out of fuel, Or running on 3 cylinders when it sorts it self out full power is back. When it does this theres no engine lights either or codes in ecu.

Thanks again lads.

 

mine did this and found a split in a pipe on turbo to intake, could be lamba sensor also.

 

Ill double check those pipe again but checked them again can I ask which pipe tha was? Lamba sensor has being changed.

But do day I have put a new knock sensor on as the old one was very corroded. Ill keep you posted if this has made a difference.

Also the question to boost its boosting at 0.9 bar.

Thanks Phil

 

change knock anyway then, check all clips,pipes,vac hoses mate also

 

Ok so for so good the knock sensor has fixed the the cold problem it don't hesitate now well fingers crossed but the other problem is still there going look at all hoses again tomorrow.

If hoses are ok anything else I can check ?

So looks like multiple components are faulty

 

0k just had a engine light come on so i plugged the two black wires under dash it flashed slow twice then 4 fast flashes any one know what that is ?

Phil

 

Just let you guys know ive sorted the problem's out finally.

The knock sensor was faulty and the idle air control valve was full of gunge clean it all out with brake clearer . she runs sweet now cold or hot happy days :-)