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Symptoms of a bad IAC valve?

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Old 04-27-2009, 09:21 AM   #1
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Symptoms of a bad IAC valve?

Hi everyone:

Need the group's collective knowledge here. I have a '98 Tacoma 4x4, V6. I am wondering what the typical symptoms of a bad IAC valve are? Sometimes (more often in the last week or so) the truck will idle around 2,000 rpm on a cold start; after a while it will go back to a normal idle.

Reason I suspect the IAC is, a while back I had a CEL on and the computer was throwing a code for a bad IAC. My mechanic cleaned out the throttle body and the code went away. Now it is not throwing a code but the idle-up is screwy. Want to be sure it is the IAC before spending $$ on the part...

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Old 04-27-2009, 11:07 AM   #2
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I had a bad IAC valve and the only symptom was the high idle, 1700 rpm cold and 1200 rpm hot, no CEL. I replaced the valve and idle has been normal since.
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Old 04-27-2009, 12:00 PM   #3
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I have actually cleaned mine up really good, actually taking it off the throttle body which can prove sometimes difficult. You have to take off the valve anyway to replace it but you can really clean it out where is adjusts in the throttle body with some carb and choke. In my V6 camry, it would start and then quit. Bad IAC. I took the throttle body completely apart, including the IAC valve and found that it wasn't even moving at all. Cleaned everything really, really good, put a little oil around the rubber gaskets to seal them and it works awesome, no more trouble. I probably used about 2 cans of Carb and choke.
BTW, if you just spray carb and choke into the throttle body with it on the car and running, it will not clean the IAC.

Last edited by stir_fry_boy; 04-27-2009 at 12:01 PM.
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Old 04-27-2009, 01:46 PM   #4
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Alright...I'm reasonably sure that is the issue. I'm going to just replace the IAC since the mechanic already reamed it out once; chances are if I just spray carb cleaner on it I'll be in the same boat in a few months. Thanks!
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Old 09-14-2009, 05:03 PM   #5
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When I had my A/C on, the idle would intermittiently drop down to 300-400 rpm's along with a "click" sound. I cleaned the IAC = smooth idle and no more rpm drop w/ the Air Conditioner on.
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Old 05-11-2016, 02:17 PM   #6
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IAC valve

Hello group,
I saw the posts concerning IAC valves.
Please tell me if this makes sense. The symptoms on my 96 Camry with 188K have been lingering on and off for close to 9 months.

~Engine dies at red lights
~Sometimes very hard to restart, 3 mins maybe of cranking.
~From drive to Park, RPM's would surge to about 2000.
~Engine never stalled while in motion.
These were very sporadic symptoms. I would have one bad week followed by 2 months of no issues.
No check engine light was on.
Code could not be obtained.
Mechanic said it had to be caught in the act. I agree.

Just by pure luck I had my car at my buddy's shop and it would not restart. He put the reader on it and it said 4 degrees. He knew that was the IAC. It was replaced and no issues in 2 weeks. No 'Park' surge in 2 weeks, that's the big thing. I am 99% sure that was the issue.
Does the above info make sense? I ask because I have to drive said Camry 1600 miles next week. I would hate to break down in the wrong part of WV. No offense.
I have looked up symptoms extensively and can not match the IAC with what mine were. Except for the idle surge part. However, there is nothing about stalling at a red light with car in drive. Then, the hard restart on a warm engine.

Thanks in advance, Jim
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Old 05-28-2016, 07:24 AM   #7
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mine would not start if the engine was warm, idle was not good.
on the 02 V6 it is easy to clean up, I think there are some write ups on it.
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