Rough idle/stall!!

[Ryan]

I've just finished rebuiliding my engine, but I'm having a problem with the idle. When first started it idles at around 2000rpm for a minute or so then drops down to idle rough as hell at 1300rpm and CEL comes on (code 24 = idle air control). So one would presume that the IAC is sticky/jammed or whatever, HOWEVER:

While all this is going on, the pipe coming off the TMIC piping for the BOV is off (no BOV installed), meaning there is a air leak. The interesting thing is that when it is 'idling' there is heaps of air pressure coming out of the pipe, but shouldn't there be vacuum?? Or is that only in the manifold there is vacuum at idle?

Anyway, as soon as I block the air leak the engine instantly stalls/dies/strangles itself. I've tried blocking the air leak then reseting the computer then starting but it doesn't like it at all, it only runs when the is a air leak from the BOV T-pipe.

If there is supposed to be air pressure in the intercooler at all times then I guess I should be cleaning out the IAC or checking neutral switch, right? Just wanna sort that out first then start with other things. Note: I have installed 2 brand new coil packs, and 4 new spark plugs, VF22 turbo (upgraded from TD05), and I did disassemble the manifold and remove IAC & throttle body. Car is a V2 WRX STi 1996.

[Guest boostin]

Unplug the idle controller, block the pipe, then start it. Does it run now?

[Ryan]

Internet is down at my house for a few days so using a mates occasionally, but I'll give it a go tonight. I gave it a clean out with brake cleaner yesterday but still the same.

[Ryan]

 boostin said:

Unplug the idle controller, block the pipe, then start it. Does it run now?

Just kills it, but I have a feeling it could be the AFM thats causing the problem, maybe dirty or broken. If you know of any one selling a green sticker AFM I'd be keen..

[Guest]

when my afm was playing up i was getting the idle air valve code as well as the afm one , do you get both codes ?

[log1call]

The ISC code could just mean the ecu wasn't able to keep the revs within the desired range.

It sounds like an air leak to me. When the revs were up, was the motor running smooth or rough?

If it was rough at all revs then there may be wrong valve timing, sticking valve/low compression or something mechanicaly wrong like that.

If it idles rough but smoothes out at revs then probably a small air leak.

[Guest]

Are you sure you've got it timed right (edit) see you said that allready log1call

Resetting the ECU so it relearns all the fuel mappings?

Injectors maybe more than likely a leak as ppl have said?

"When the revs were up, was the motor running smooth or rough?" yea this should Determine if a leak is present as such as the car’s vacuum goes down at higher rpm is applied

[Ryan]

 log1call']

It sounds like an air leak to me. When the revs were up, was the motor running smooth or rough?

It's a bit hard to tell, but smoother if anything. At the moment I'm not too worried about it running rough, just want to get the revs to idle lower around the 800rpm mark instead of 2k! Altho they could be tied in together I guess?

Are you sure you've got it timed right (edit) see you said that allready log1call

I think so, if it wasn't timed right would it make it idle at higher revs, e.g. 2000rpm?

[quote name='WiLd02StI said:

Resetting the ECU so it relearns all the fuel mappings?

Yep tried that, reset it by leaving battery cable disconnected over night, it clears the error codes so guessing it resets the fuel mapping

[log1call]

"It's a bit hard to tell, but smoother if anything."

Sounds like a fairly big air leak to me. Check all the hoses are on, aren't perished/holed and that they are attached to the right places.

[Ryan]

The only air leak is the BOV pipe coming off the intercooler piping, but if I block that it kills the engine pretty much instantly? Weird aye?

[Guest boostcut]

have you got good vacuum on your guage? how about trying to run the engine without the afm plugged in?

[Ryan]

I'll hook a vacuum gauge up tomorrow and let you know what its at, should it still have strong vacuum when the butterfly's closed even tho it's running at 2000rpm?? Doesn't run when the AFM's not plugged in.

[log1call]

Are you in Warkworth Ryan?

I think we might have talked before through trademe?

If you disconnect the AFM and connect the BOV what happens?

The air that's coming out of the BOV pipe has been measured and the fuel mixture is being calculated to use that air. If you disconnect the AFM's wires the ECU will stop using it and calculate the mixture from the TPI and the revs, then you should be able to connect the BOV and it should still run.

[log1call]

Boost beat me to it.

There should be vacumm if the throttle is shut.... Unless you have an air leak!

[log1call]

For a motor to do 2000 revs it needs air, more air than gets past a shut throttle.

[Ryan]

Yep I'm in Wellsford just north of Warkworth, erm, when did we talk? Probably have thru TM tho.

I'll disconnect the AFM and connect BOV tomorrow, sadly the phoneline is down at my place until tomorrow or Wednesday so have to use internet at the mrs place. Where abouts are you?

[log1call]

I'm up north. We talked a year or so ago when you were first getting a subaru. I was telling you how to connect a laptop to one, amongst other things... starter problems I seem to recall.

[Ryan]

 log1call said:

I'm up north. We talked a year or so ago when you were first getting a subaru. I was telling you how to connect a laptop to one, amongst other things... starter problems I seem to recall.

Ahh gotcha!! Yep I've saved all your emails for when I experiment with the laptop in the future, when I was talking to you I had a 97 Forester, since then I've got the WRX and my RSB. Good memory, starter was the problem, just chucked a new 2nd hand one on and sold the beast lol.

[Guest boostcut]

have you played around with the tps or the throttle stop on the throttle body? as this could be your problem.

[Ryan]

I pulled apart the manifold but didn't disassemble the TPS, maybe I reset/adjust it anyway??

[log1call]

Have you seen... http://www.clubsub.org.nz/forum/index.php/topic,5652.0.html

And... http://www.clubsub.org.nz/forum/index.php/topic,5902.0.html

[Guest boostcut]

yeah, that maybe a good idea? have you had a good look around and make sure you put all of the hoses on? as it sounds like a major vac leak to me. get some carb cleaner and spray around intake manifold, my bet is split gasket etc...

[log1call]

Ha, yeah, a gasket with too much silicon on it!!

[log1call]

Just teasing Ryan.

It wouldn't be the first time it had been done though.

[Ryan]

 log1call said:

Have you seen... http://www.clubsub.org.nz/forum/index.php/topic,5652.0.html

And... http://www.clubsub.org.nz/forum/index.php/topic,5902.0.html

Yep thanks read those post of yours awhile ago and book marked them for the future, I don't think my idle needs adjusting tho, just gotta sort out the fault that's causing it.