Enlighten Me


AngryLepercon

AngryLepercon

15+ Year Member

Joined
Sep 1, 2008
Messages
2,150
Points
3,101
City
Maryland
Vehicle Year
1999
Transmission
Automatic
Enlighten Me
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What is that part in the circle called?
 
Idle Air Control valve (IAC) I believe. Another member can confirm.
________
Suzuki GV1400
 
Last edited:
automatic nitrous lubricating recipricator sending unit:buttkick:idk
 
yep that is an IAC (idle air contorl valve), if it is bad your truck will either idle to high or to low and possible stall the engine, sometimes like in hondas when it goes bad the engine alternates from high rpm to low rpm as if you were revving it. If you dont know what it does, it lets air in to the intake when your throttle is closed.
 
Mine doesn't seem to have problems RPM wise it just makes this horrible noise on start up. and I think it has to do with a bad shutter for the first 2 min of it running.
 
Possibly the computer is making it do that and it may itself be working fine. I wouldn't throw it out until I was sure it was bad. It's a very simple part. Pull the plug and put an ohmeter across the pins on the ISC--you should see in the neighborhood of 10ohms. If you do, the windings are in good shape. Then take it off and take it apart and look at it.

Then use a voltmeter, turn the key on and see if one of the pins on the harness is giving 10.5 or so volts and remember which one that was. Plug it back in and backprobe on the other pin with the engine running. When you vary the rpm you should see the voltage on that pin move from between 3 and 11.5.

If you've gotten that far, the ISC is fine and something else is making the computer try and correct the idle like crazy--causing that noise. Manifold leak, temp sensor--time to troubleshoot.
 
I think it is the part itself to be honest not the computer but I could be wrong. Once I had it running just finished changing the oil and it started humming pretty bad i took the wrench i had and tapped it and it went away. So it is in the part somewhere.
 
To my knowledge, alot of time when that thing goes bad, it will make a noise and if you listen for where it's coming from, it sounds like it's coming from the airbox/ intake, when it really isn't.

Mine has kind of an eratic idle (like somethin isn't compensating correctly) after you let up on the throttle while moving (from say 1/2 throttle, to 1/4 throttle).

I figured I'd take the vavle out of the Explorer I got, and put it on, and it still does the same thing.


Those valves are spendy though if I remember right...
 
Wow. I would just like to comment on how this is the first thread i have read in a while where it was straight tech info. No BS or argument. Its very nice to see.
 
Yup, that would be the idle air control valve. I think the one for my 2.9 was about $50 and it solved some weird idle problems I was having.
 
dogboy said:
To my knowledge, alot of time when that thing goes bad, it will make a noise and if you listen for where it's coming from, it sounds like it's coming from the airbox/ intake, when it really isn't.
Click to expand...

Thats exactly where it seems to be coming from.
 
just beat it with a hammer until it stops, usually works for me, and then i have to fix something else that was damaged in the process,
 
I did that once and it did stop but came back the next day. I don't know is there a float that could be stuck or a bad seal somewhere?
 
i've cleaned them before and fixed it..

when mine started making noise i just replaced it.
 
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