Idle Air Control Valve
- Capn Crunch
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Idle Air Control Valve
Hi all,
After replacing the fuel pump on my starboard engine injectors had a much better pattern but engine would still stall as soon as put into gear. After mechanic inspection he identified the source of stalling as the Idle Air Control Valve I'm having trouble sourcing the shown part and the only number I can find is on the unit itself: 59559 (and directly under that number is: C0244&)
I did find a part @ AutoZone that looked the same at first glance, tried it and after ECU tried to map it idled at 1250rpm.
Wasn't an exact match it turned out - so I took OEM part to NAPA and they found a part in their warehouse that looked identical but showed fitment exchange for 88-92 vehicles that mostly had 6 cyl. motors not V8. Gonna give it a try, but hoping someone here has some insight into sourcing the actual replacement.
Also, I was told yesterday that when that part gets replaced that a process of adjusting the idle speed is necessary, but no indication of how to do that in a TBi setup. Anyone that can confirm that?
One other question - is it worth the effort to try using some PB Blaster to free up the mechanism on the old control valve?
Any help would be greatly appreciated!!
Mark
After replacing the fuel pump on my starboard engine injectors had a much better pattern but engine would still stall as soon as put into gear. After mechanic inspection he identified the source of stalling as the Idle Air Control Valve I'm having trouble sourcing the shown part and the only number I can find is on the unit itself: 59559 (and directly under that number is: C0244&)
I did find a part @ AutoZone that looked the same at first glance, tried it and after ECU tried to map it idled at 1250rpm.
Wasn't an exact match it turned out - so I took OEM part to NAPA and they found a part in their warehouse that looked identical but showed fitment exchange for 88-92 vehicles that mostly had 6 cyl. motors not V8. Gonna give it a try, but hoping someone here has some insight into sourcing the actual replacement.
Also, I was told yesterday that when that part gets replaced that a process of adjusting the idle speed is necessary, but no indication of how to do that in a TBi setup. Anyone that can confirm that?
One other question - is it worth the effort to try using some PB Blaster to free up the mechanism on the old control valve?
Any help would be greatly appreciated!!
Mark
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- bud37
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Re: Idle Air Control Valve
They can be cleaned but you need to be careful.....there are videos on u tube that will help with that side of it. To check operation you should really be connected to a scan tool of sorts.
Regarding the first start with the new one there is a procedure for it to learn where closed and open is.......again check on line for your year and engine combo. Seems like the one you put in was staying open and not trying to control the idle speed......which is the job of the ecu. Also check out the crusader parts source for the number then cross that if you want to go to Napa, pep boys , advance etc. I have got stuff from them and it worked just fine.
Make sure the throttle plates and body/ flame arrester are clean.
Regarding the first start with the new one there is a procedure for it to learn where closed and open is.......again check on line for your year and engine combo. Seems like the one you put in was staying open and not trying to control the idle speed......which is the job of the ecu. Also check out the crusader parts source for the number then cross that if you want to go to Napa, pep boys , advance etc. I have got stuff from them and it worked just fine.
Make sure the throttle plates and body/ flame arrester are clean.
FWIW.....The above is just my opinion.
- pepmyster
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Re: Idle Air Control Valve
Had the same problem, VP 8.1's. Goggle IAC 3843751. This is what I used, worked fantastic. Hope this helps.
- Capn Crunch
- Deck Hand

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Crusader 350XL injected, Hurth Inboard - Location: On the Mighty Columbia River in the Pacific Northwest
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Re: Idle Air Control Valve
Thanks very much, I think it's beyond cleaning. The issue I'm finding is several look the same, but very few are worm-gear driven - most are more like a solenoid.
- Capn Crunch
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Re: Idle Air Control Valve
Thanks, that one actually looks like it might work! As mentioned in my reply to Bud above most aren't worm-gears... do you recall whether this referenced one is, or more like a solenoid?
- pepmyster
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Re: Idle Air Control Valve
Gezzzz so hard to remember...Most likely a worm gear since it always variable in opening the passage. I noticed another number I put in my notes, 217435. All were for gm v6 and v8 engines.....
Last edited by pepmyster on August 11th, 2021, 7:06 pm, edited 1 time in total.
- bud37
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Re: Idle Air Control Valve
They are small stepper motors that open and close in counts and need to be partially open when at idle to keep the engine running. They do look different, but don't let the application fool you, the same ones are used in many different apps. Check the wiring connector as well.
FWIW.....The above is just my opinion.
- bud37
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Re: Idle Air Control Valve
Oh I just thought.......have you put the working one from the other side in to try it and make sure it is the IAC ?
FWIW.....The above is just my opinion.