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Old 10-21-2012, 09:13 PM   #1
Kijho
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Default Rough Initial Idle 95' sti

I've read over so many threads, gone through the hesitation thread, been all over various forums and still somewhat stuck. Perhaps someone can give me some specific input from the video below.

I've done:
Coilpack conversion
Sparkplugs
Oil change
MAF clean / Checked
Airbox filter clean / checked

Have not done but have read on:
Injectors
IACV



Only happens after it's been sitting overnight or all day in the cold.
Predicting some -20celcius here next week so starting to get worried.

I believe this is my IACV??
Every thread I've read in regards to my problem seems to point towards a guide with a completely different looking IACV above the Throttle body.. which I don't see on mine.


Thank you
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Old 10-21-2012, 09:17 PM   #2
dirtslayer
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Not sure if that's your iacv, because I haven't seen an older sti engine.
But if I were you, id look for 2 small coolant lines and a elec harness plug on the suspected iacv. It can only be on throttlebody or upper intake on some cars.

Check vaccum?
Check fuel ratio?
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Old 10-21-2012, 09:21 PM   #3
Kijho
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Quote:
Originally Posted by dirtslayer View Post
Not sure if that's your iacv, because I haven't seen an older sti engine.
But if I were you, id look for 2 small coolant lines and a elec harness plug on the suspected iacv. It can only be on throttlebody or upper intake on some cars.

Check vaccum?
Check fuel ratio?

I don't have a gauge for ratio. My boost peaks the same as always, car runs perfect after the first 5-10 seconds or so.
The other night the rough initial idle / start was so bad however it actually stalled.
Some of my GC friends haven't had a single issue similar to what I'm experiencing, and then some of them have the absolute identical problem.

Runs 94 octane on stock ecu and stock everything else.
55,000km's original engine.
Changed fuel pump & filter recently. (To a used filter from a newer GD)
No leaks or anything anywhere.
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Old 10-21-2012, 10:17 PM   #4
Jessekrs123
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The picture you posted above is an early IACV, which should be similar your IACV. They mounted them in all different places on the intake manifold on the early models.

The newer ones are integrated onto the top of the throttle body, whereas the early IACVs were mounted directly to the intake manifold.

There should be 4 10mm bolts, a coolant feed and outlet, and some sort of hose that supplies it air when the throttle is closed.

Definitely not an extremely difficult task to take it off and inspect. These tend to gum up which makes it difficult for the valve to function properly at times, especially as it becomes colder.

Take it off and inspect it. If the IACV is your problem, then good. If not, my next thought would be your coolant temp sensor is at fault which could also explain a rough start/idle.
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Old 10-21-2012, 11:25 PM   #5
Kijho
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Thanks Jessekrs, so I would undo the 4 bolts and undo the hoses going in/out of the entire metal body that seems attached to the manifold?? (Picture above looks identical to mine)

I don't take the top yellow housing off but the actual entire metal piece as a whole??

Would I need any new gaskets of sorts before I go and do this to be prepared for that I can pick up at my subaru dealership tomorrow on the way home from work??

Take off this piece, check for it being gummed up with stuff, use brake cleaner and something that I can use to gently wipe / clean grime off from the inside I'm assuming of this casing and valve?

Thank you!
Cheers!
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Old 10-22-2012, 10:26 AM   #6
Kijho
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Bumpp
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Old 10-22-2012, 03:19 PM   #7
dirtslayer
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Yea, get the gasket because its imperative to have a proper seal. Then clean it up , reinstall.

But then again, id check vaccum first, that'll tell you if youre leaking air or not
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Old 10-22-2012, 10:47 PM   #8
Kijho
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Don't think I'm leaking air anywhere or anything.

I left the car out today in the -7c (Windchill a bit colder) for about 6 hours today.
Went out this evening to fire up and move to the garage only to stall 4 times.

Car turned over instantly, and then stalled dead silently in less than a second.
After 3 or 4 stalls it fired up without a single hesitation and ran perfectly fine.

Getting colder really want to fix this for good
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Old 11-21-2012, 08:19 PM   #9
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Bumping this thread up -
Swapped to newer (used) injectors and it still started insanely rough. If anything it seemed to even found worse, louder few knocks as it struggled not to stall when I started today in -13c

Help I've tried everything I can think of. (Excep iacv, but my iacv is confusing as hell)
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Old 11-21-2012, 08:26 PM   #10
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Quote:
Originally Posted by Kijho View Post
Bumping this thread up -
Swapped to newer (used) injectors and it still started insanely rough. If anything it seemed to even found worse, louder few knocks as it struggled not to stall when I started today in -13c

Help I've tried everything I can think of. (Excep iacv, but my iacv is confusing as hell)

d000000000d...this is the wrong forum for this

north america never got that car

you need the pre-2002 turbo forum...not this one
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Old 11-21-2012, 08:27 PM   #11
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how about the coolant temperature sensor???

how about smoke testing to find the leak???
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Old 11-22-2012, 07:55 AM   #12
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Fuel filter hasn't been mentioned.. but I'm picking at nitpicks..

There's been talk of the IACV, but no conformation that it's been gone through...

IF you do, have gasket in hand, they swell from coolant contact, they don't go back in on assembly..
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Old 11-24-2012, 10:05 AM   #13
Kijho
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Swapped brand new fuel filter no luck.
Then decided to try swapping brand new to Walbro pump - no luck.
Sparks, coils, oil, etc. done.

I haven't done the iacv yet though, I do have a gasket on hand, it's not the rubber gasket though, it's alot different. I have the iacv I believe in the above picture I posted, but I have no idea how to take it off / clean that type of iacv, all the DIY's show the iacv being a small part ontop of the throttle body.

Mine's that massive piece over on the right of my intake manifold
Not sure how to get a few of the hoses off, they don't have any clamps around them but seem to be attached somehow.
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Old 11-30-2012, 02:51 AM   #14
Kijho
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Does anybody have any information in regards to adjusting the IACV?
I see there are 2 screws, one on each side of the actual top of the control valve as pictured above. Would adjusting this valve has any effect?

I'll be taking it all off tomorrow to give it a good cleaning inside.
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Old 11-30-2012, 07:49 AM   #15
Jessekrs123
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Quote:
Originally Posted by Kijho View Post
[IMG]
Does anybody have any information in regards to adjusting the IACV?
I see there are 2 screws, one on each side of the actual top of the control valve as pictured above. Would adjusting this valve has any effect?

I'll be taking it all off tomorrow to give it a good cleaning inside.
I've messed around with the valve, setting it at different positions, and I found it doesn't really matter the degree in which you turn it too.

I've set it at the highest point, and it idled very high at first, then once the ECU learned it's position, it set itself back to a 500 rpms warm idle.

I've set it incrementally to the lowest point (setting it from highest to lowest instantly caused it to stall) and the warm idle would make it's way back to 500 rpms.

After that I just set it to what was marked by the white markings. It doesn't really matter where you set it too, but there is really no need to adjust because the ECU learns the position of the valve and adjusts accordingly.

If you are having trouble with the IACV, here is a video I made:

As Scotty and I have previously stated, the coolant temp sensor could be at fault as well. I have early coolant temp sensor resistance measurements you can go by if you want to test. (Haynes book is ridiculously incorrect with their resistance table)
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Old 11-30-2012, 11:58 AM   #16
Kijho
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Thanks a ton for that video, helped me a huge amount.
Only question is once off, how could I effectively clean inside that area? If that's the case and it's "gummed" up - I can't really get into the iacv as much as I thought I could originally! (Judging form your video)
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Old 11-30-2012, 06:54 PM   #17
Kijho
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Sooo......





Cleaned it pretty well, I used about 40 Qtips and brake cleaner, I would slowly pull the green "valve" part so it was fully closed, in behind it was a lot of black gunk, so I got everything off gently especially near the edges where the valve seemed to meet with the casing.


Then took out the small 1 way valve and gently cleaned the front and back of it. The rings were all in great shape, what you'd expected from a car with only 50K on it.


Couldn't do much about the black "ring" behind the "wheel" on the valve above. Didn't want to mess it up or anything.

Then, fired up. It's about -14celcius out and the car has sat for approx 15 hours overnight in the (non heated) garage.
Ticks 6 seconds in.


To update what I've DONE in hopes of fixing this problem:
I've done:
Coilpack conversion (Many months ago when I first got the car, went smoothly)
Sparkplugs (Vex Performance did this few months ago while doing valve cover gaskets)
Oil change (Within 1000km's)
MAF clean / Checked
Airbox filter clean / checked

Injectors (Not "brand new" injectors, but "newer" injectors from a friend's ride)

IACV Cleaned (Used Brake Cleaner / Gasoline with Qtips to gently scrub gunk out. It WAS pretty dirty, spent about an hour cleaning it, also cleaned the 1 way valve ring, opening to the throttle body where the valve sits, and the lines coming from the IACV itself with qtips)
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Old 12-01-2012, 11:21 AM   #18
69subaru360
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My 95 WRX engine used to do that on a cold start. If I turned the key on and off a few times to prime the fuel pump, it started normally. I think the old pump was bleeding down pressure. Since I upgraded to a walbro and bigger injectors it has been normal.
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Old 12-03-2012, 12:16 AM   #19
Kijho
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Should have put that in what I've done too.

Walbro fuel pump
New fuel filter
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Old 12-03-2012, 12:20 AM   #20
i_c_the_light
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Used to have this problem on my old '90 LGT and my TZ wagon. My flatemate has this on his '93 GT-S2.

I'm blaming the fuel pump.
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