Help with unknown problem - vacuum leak?

[Frodo88]

Hi all,

First off any help would be great, I'm currently at a loss of what to do next. I have searched high and low to find someone having a similar issue but haven't found anything.

First off its a GC8 STI v5 with twisted turbo set up and FMIC.

I picked it up for a good price but it needed a fair amount of work which I've been doing. Although this one problem I haven't been able to resolve...I don't know a lot about turbos.

The symptoms

Starts up fine and idles fine when cold - drives as normal when cold. Once warm when ever you put the clutch in to change gears it almost kills the engine....goes down to about 200 rpm then a second later it kicks back to life. Almost as if its telling itself hold on I'm meant to be on. About 15% of the time it will actually stall though - starts up fine again after that. It normally idles alright, some time it searches for a bit in the rpm before it settles.

Not sure where to start - its not a MAF issue as it runs sweet its simply just when the clutch is depressed.

BOV, waste gate? I'll put some pictures up soon once I work it out, haven't done it since the forums changed. - if anyone can help in regards to where they exactly go or what the issue might be would be awesome!.

[Rosssub]

Check for vac leaks and try giving the IACV a clean out.

[Marky]

Tighten or block the bov, rule that out

[Frodo88]

Some photos encase someone can tell if this has been wired/hosed up wrong.

[Marky]

Only thing which I can tell from the photos is the hose on the bottom right of the bottom photo - with the blue cable tie? Where's it going?

A problem like you describe with it falling over at idle or clutch in is almost always the idle stepper motor, a leaky BOV / intake or in a subarus case can still be the AFM, especially that particular one. Any kind of a vacuum leak can really hurt driveability and will give that stumble at idle you describe since the airflow is so small then

To be fair it probably just needs all that vacuum hosing gone over and done nicely, there's a lot of blanked off hoses etc which won't be helping find the problem

[Frodo88]

Hi,

Thanks for all the input.

That pipe from the inlet runs back into the brake booster. - normal?

Yea I'm aware it needs a real good tidy up; how should the hoses be blocked up to prevent vacuum leaks, obviously not with a screw?

[Minaj]

When I when rotated turbo on my V7 Sti the same issue use to happen to my car all the time. The AFM has to be a certain distant away with 90 degree bend also in place. What I did to fix my issue is I placed the AFM a bit further away from the turbo which fixed my issue.

[Guest]

I had the issue put in a long 45deg 3in bend that put pod right behind headlight which fixed it. Pics in my garage thread.

[boon]

On an unrelated note, please relocate your siren before someone taxes your car, only cowboy fly-by-nighter installers put the siren on the pillar like that.

[Frodo88]

Cleaned out the IACV, there was a lot of gunk in it. Has improved it during driving but still getting the stumble on idle.

Going try extending the pipe as mentioned.

Can someone post the link to that garage thread evowrx is talking about, tried searching but couldn't find it.

Thanks again.

[Guest]

http://clubsub.org.nz/forum/showthread.php?28043-GF8-wrx-family-wagon

Ran weird like this:

http://i1145.photobucket.com/albums/o501/clintyluvzhopey/SANY0112.jpg

Ran fine like this:

http://i1145.photobucket.com/albums/o501/clintyluvzhopey/SDC10992.jpg