Does the IAC valve need to be adjusted?

Does the IAC valve need to be adjusted?

Postby uofurex [OP] » July 19th 2013, 10:40pm

I just installed an Idle Air Control (IAC) valve and I am wondering if it needs to be (or can be) adjusted? I changed out the old one because my Van is idling rough. With the new IAC in the Van, it ran great for about 15 minutes, then the rough idle came back. Any help would be much appreciated!
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Re: Does the IAC valve need to be adjusted?

Postby chevymaher » July 20th 2013, 4:58am

No it can't be adjusted on a 95.
Unless You pay incredible amounts of money. Take college programming course. Put in a chip socket. Buy a chip burner. Buy a chip. Experiment with burning a chip. Learn how to use the free programming programs. Learn to direct the computer to use the port that program wants. Find the port that the program trying to use.
Computers are cheaper and easier.

Remember that turning that screw a half turn to idle it up for free was a lot harder than it seemed.
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Re: Does the IAC valve need to be adjusted?

Postby redfury » July 21st 2013, 3:08am

uofurex wrote:I just installed an Idle Air Control (IAC) valve and I am wondering if it needs to be (or can be) adjusted? I changed out the old one because my Van is idling rough. With the new IAC in the Van, it ran great for about 15 minutes, then the rough idle came back. Any help would be much appreciated!


The IAC is self adjusting. Turn the key on for 10 seconds, then turn off. The IAC will seat itself and then back off a predetermined number of "steps".

If you are still having idle problems, then you either have a blockage at the IAC port, or something else. You can also test the iAC function by disconnecting it and starting it up after doing the 10 second key reset. If it idles fine and doesn't go bad, then you have something that is telling the computer to adjust the idle. Realistically though, all the IAC does is adjust the idle speed by allowing more air into the intake, which is determined by engine load ( such as turning on the A/C or putting it in gear ). It sounds to me more like you may have an EGR issue.
A temporary fix usually becomes a permanent solution, therefore it does not exist.
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Re: Does the IAC valve need to be adjusted?

Postby uofurex [OP] » July 26th 2013, 6:42pm

I did not do the "Turn the key on for 10 seconds, then turn off. The IAC will seat itself and then back off a predetermined number of "steps"." step after installing the IAC, would that matter?

The EGR was also replaced prior to replacing the IAC. The guy who owned the Van before me replaced this. Is there a way that he messed this up you think?

Thank you so so much for your response
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Re: Does the IAC valve need to be adjusted?

Postby redfury » July 27th 2013, 7:16pm

Everyone on the board will agree that whenever the EGR is replaced or serviced it should have the "clean screen" gasket used in place of the normal open one, which will block any carbon deposits from getting to the valve and causing it to stick open. The EGR will cause idling problems if there is an issue with it. Usually the IAC isn't a problem, even if a code comes up for it...it's just usually running outside of it's parameters trying to compensate for something else.
A temporary fix usually becomes a permanent solution, therefore it does not exist.
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Re: Does the IAC valve need to be adjusted?

Postby Leeann_93 » August 1st 2013, 1:46am

^ yup, pull the EGR, clean the pintle and seat, clean the bore which feeds it, reinstall with a Dorman/HELP! Clean screen gasket.

Have you tested fuel pressure/leakdown? What kind of mileage are you seeing? In the case of both my '93 Bravada and '93 Astro with CPIs, the fuel pressure regulator and 'nut kit' were leaking under the plenum. That's what carboned up the EGR valve and caused it to idle like crap once it warmed up.
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