15 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHIACV (Idle Air Control Valve)
Reported or suspected cause
documented in other thread
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that report identifying a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Leading evidence: 'documented in other thread' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'documented in other thread' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check crankcase vacuum' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
Replaced MAF sensor and cleaned IACV a little bit.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
Cleaned more and since then it has been idling perfectly.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
Idle problems came and went, parts were replaced, parts were cleaned, etc.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
15 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T194705Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
For those of us with '99 & '00's with idle air control valves...
I had a hell of of time tracking down some idle issues this year. Problem was documented in other thread. Idle problems came and went, parts were replaced, parts were cleaned, etc. Basically the idle would hunt from 600rpm to 1000rpm up and down up and down. Or it would stick at about 1200.
As it turns out I find that I have to clean my IACV about every 1500 miles. I spray it with carb cleaner, use a soft brush and scrub it best I can. Activate it with a 9 volt battery and spray it with more carb cleaner. Let it dry. Then spray liquid wrench dry lube before installing. Idle instantly runs perfect immediately afterwards and for about 1500 miles.
Anyone else having to do this?
Anyone know if there is something to prevent it from getting dirty?
Does this suggest that something is amiss in my engine or is this typical?
Thanks.
Just changed oil this week with JG DT40. Was planning on doing it next change in 6 months.
What's the connection with semi-clogged pick-up screen and the IACV?
I had an intermittent hunting idle, mostly when doing Autocross or equivalent heavy driving. While installing the FVD sump I found some plastic bits on the oil pickup screen blocking about 30% of it. After cleaning those off I never had the issue again.
FYI, you came use a 55 micron filter on a 5 gal bucket to strain and reuse your oil if you decide to drop your sump. Also the following were recommended and came handy when dropping it.
Brass brush
Rubbing alcohol
Brake cleaner
Razor blade
Loctite 5900
New bolts
7.5lbs torque wrench
Don't know what the correlation would be between the oil pickup tube screen and the IACV. But I can tell you that when mine starts to idle crappy I head straight for the IACV. I have no idea how that gets so gunked up but it does. I use the 9V battery and Q-tips with carb cleaner. Usually it is black with stuff. Clean until the valve is shiny, the little part that rotates inside the valve. I actually thought it was black! Turns out it is shiny metal. Too bad a new OE is $562. Was just going to replace but when I saw that it was clean, clean, clean! Always fixes up my idle, nice and steady. I've done this probably 4-5 times in the last 30K miles...just for reference.
I'm curious if you guys checked your crankcase vacuum. I wonder if an ineffective/failed AOS will contribute to this issue. Even though the AOS is after the idle valve, maybe the air flow can somehow cause the blow-by to contaminate the idle valve.
Well, I do have to admit that the times that I've had the TB off and removed the IACV, I've only given it a cursory cleanup. Along with the MAF sensor. So it started with replaced OE starter, cleaned up IACV a little bit, sprayed with some cleaner and re-installed. Replaced AOS and cleaned up IACV a little bit. Replaced re-manned starter (big mistake) with new starter, cleaned up IACV a little bit. Replaced MAF sensor and cleaned IACV a little bit. That was all good. Then idle went haywire and pulled the TB, removed ICAV and totally cleaned it out with the carb cleaner, soaked it for 24 hours and Q-tips, activating it with 9V battery. It was a bit sticky and the valve would work, then it would not. Cleaned more and since then it has been idling perfectly.
I know of 2 ways to tell if AOS is failing, one is excessive vacuum when removing the oil cap, the other is smoke form tail pipes. My car shows neither of these. My indy has never mentioned AOS concerns.
As far as I know my '99 has original AOS, is there any other test you know of that I can perform?
What tests would my indy do to verify a failing AOS?
You can't test it accurately with only removing the oil cap. Yes, if the cap is very hard to remove, you know for sure the AOS is bad. However, if the cap is not too hard to remove, it's inconclusive because the vacuum of good and bad only differ by a few inches of water.
You need to use a manometer. A healthy AOS should read about 4~5 inches of water. If you get beyond say 8 inches, the AOS will need to be replaced.
Any pics of the valve itself, and where on the throttlebody it is located? I have a 2000 with rough idle as well. I know the supercharger liquid-to-air cooler has some oil in the bottom that I need to drain out/clean.
I noticed some dirt sticking to oil around my throttle body and boots, and the back of my AOS is the same so I'm just going to change mine as maintenance... probably when I do that alternator/starter Y-cable.
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