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Old 03-15-2005, 12:55 PM   #1
CirrusWRX
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Default High idle, CEL, Outback EJ25, misfire, related?

I'll do my best to lay it all out there to be as complete as I can be.

Car
1997 Legacy Outback Wagon = engine replaced at 150,000 miles by me with much help from friends. Cause of death still unknown, but cyl #3 had 0 compression, made a really nasty ticking sound, idled lumpy (ran on 3 cylinders...) and CEL's out the ass. Valve problem? Piston problem? Don't know, but it sounded like a Diesel engine before it let go.

Engine transplant came from a 1998 low mileage Forester with new headgasket, timing belt, and nicely resurfaced heads- same EJ25 engine, but reused the 97 intake manifold, odds and ends, and whatever wasn't on the new motor.

Car has been running very well, with over 8,000 miles on it since the "swap" with a few exceptions that I am asking for advice and direction about.

Problem
Shortly after working out a few bugs that were my fault, we noticed that the CEL would come on about 50-200 miles after resetting it via OBD II scanner: P0507 Idle control system RPM higher than expected, which was true because the car always wanted to idle at just a tick above 1000 RPM, even after it was warmed up. We also got P0303 Cylinder 3 misfire detected and P0304 Cylinder 4 misfire detected which I think has been solved, though it COULD be related.

In an attempt to fix all of the above, here is what we have performed.

1. New spark plugs, gapped correctly.
2. New spark plug wires
3. New coil distributor pack
4. New fuel filter
5. New EGR
6. Did our best to inspect all hoses were routed correctly, no obvious tears/leaks (visible)

As of all of this, the misfires have seemed to go away - they happen, seemingly randomly, only for about 5 seconds, maybe once every 500-1000 miles. *I* think it actually has something to do with gas/fuel related, but I'm also willing to accept the high idle has something to do with it as well. I figure if we can solve the high idle, then we'll tackle the misfires (or hope that they go away by themselves...)

Last night, in an attempt to try some more things, I cleaned the MAF (looked brand new, but shot it with electronics cleaner nonetheless.) I didn't have time to take out the idle air controller, but I want to definitely clean that out. I shot the throttle body with throttle body cleaner.

I know there is a whole troubleshooting sequence for the IAC but we just didn't have time to run through it. It's definitely "working" in some fashion, because we let it idle and then unplugged it and the RPM's dropped (car almost stalled.) Adjusting it clockwise would yield higher RPM's (like 2000 RPM idle) and counter clockwise would yield lower RPM's on startup, but it would then just sit and hover at a hair above 1000 like usual, even if I secured it all the way counter clockwise.

TPS changes would cause it to hunt for idle, so we put that back to where it was. Throttle cable seems to have proper amount of play, throttle response is good when blipping in neutral and accelerating normally. Car drives great and can't notice any changes when cruising, until, about 50-200 miles later, while cruising or while stopped, the CEL will come on and it's a P0507. No behavioral changes WHILE the CEL is on (driven for hundreds of miles with it on, get the same gas mileage, etc.)

As I said, I want to clean the IAC (or get another one to swap/test it out with) and there is still a very realistic possibility there is a leak somewhere that I haven't found yet, but I'm looking for any and all suggestions.

What I find bizarre is the fact that the car seems perfectly happy idling at 1000 RPM, but I know this isn't right. But I would expect it to "hunt" or idle roughly if a sensor was whacked out or clogged up. I also have a newer set of injectors I may throw on there for gits and shiggles (possibly related to misfire CEL's, but we *may* have solved that...)

Any and all suggestions welcome! Thanks in advance if you read all my crap.
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Old 03-15-2005, 05:15 PM   #2
CirrusWRX
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Bump for the night crowd?
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Old 03-16-2005, 10:37 AM   #3
CirrusWRX
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Any ideas anybody?
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Old 03-17-2005, 09:29 AM   #4
CirrusWRX
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Old 03-17-2005, 09:47 AM   #5
Mulder
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So the IAC on the motor now is the original 97 one? I'd definitely try cleaning that first and see what happens. Maybe put a vacuum gauge on it and check for possible leaks that way.
You replaced the EGR, which is good, but there could still be an issue with that. If the valve isn't closing fully for some reason, or there is leakage across the gasket from the exhaust side to the manifold side, a small vacuum leak could result.
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Old 03-17-2005, 02:42 PM   #6
CirrusWRX
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Thanks Mulder - I was getting lonely!

Yeah - the IAC in there is the original 97 with 158,000 miles on it, so I'm betting it's in desperate need of a cleaning, but I don't understand why it would idle (stably) high- I could understand if it was hunting, or if it didn't work at all (unplugging it allowed the idle to drop down rapidly and ALMOST stall the car...)

Just got the word last night that the car made it from New Brunswick up to Vermont, non stop with no CEL. Then, he turned off the car, unloaded some stuff, went BACK to the car and had to turn it on to move it, and BAM: instant CEL.

Of course, during the entire trip it was idling at 1000 RPM. *shrug*

I'm still wondering if there isn't a stupid leak somewhere that I just can't find. I take it there is no "easy" way to find it, like misting the engine with soapy water or anything, is there?
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Old 03-17-2005, 02:52 PM   #7
Mulder
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You can take a can of something combustible, like carb cleaner, and while the engine idles spray a little around the areas where you suspect there might be a leak. If there is indeed a leak at that spot the idle speed will change.
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Old 04-27-2005, 11:26 PM   #8
CirrusWRX
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Still haven't found a solution- hoping to find a local area that can pressurize with a "smoke system" to see if anybody can detect where air might be coming from.

Anybody else care to chime in?
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Old 04-28-2005, 08:35 AM   #9
staticfritz
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kyle,
p0507 is only detected after 2 driving cycles - thus the cel after loading up.
i emailed you the pages for diagnosing p0507
looks like you'll probably just have to replace the iac from what i'm reading....
lemme know if you need any other pages.
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Old 04-30-2005, 11:27 PM   #10
CirrusWRX
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2002 x2 Silver WRX
Sedan, White WRX Wagon

Default

I think I might have fixed this damned thing!

I'll post more about it when I have confirmation over a couple hundred miles, but basically, it came down to cleaning the IAC. I took another IAC from a 97 impreza that I had and cleaned the heck out of it with intake manifold cleaner, movied it around, cleaned the little wagon wheel thingy that sits in the air passage, etc. Had to mess with the settings a few times to get it to idle properly, but now, it appears to start very well when cold AND hot, and idles right around 600-700 RPM.

Hopefully this was it and doesn't require hunting for an intake manifold or other vacuum leak!
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Old 05-01-2005, 03:11 AM   #11
staticfritz
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rock on
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