Where is the IAC located?

S

s-crazy

New member
Hello SY/TY Members! :D

I'm trying to determine if my IAC is the issue of why my truck will not idle after it warms up. I can get it started with the aid of spraying starter fluid down the turbo inlet, and it will idle for about 10-20 seconds (only cold), but once it warms up, it dies once the rpm drops below around 1300 rpm. I can keep her running manually by keeping the idle above 1300 rpm, but once I let go of the throttle, it just shuts off. Anyway, where is the IAC located? I read in one of the threads, that you can disconnect the IAC while its running to determine whether it may be bad.

Thanks,
Chris
 
S

s-crazy

New member
Re: Where is the IAC located?

I'm assuming it's got electrical lines running into it, but does it have vacuum lines running into it as well? I tried to attached a digital picture of the throttle body just to make sure I'm looking at the right thing, but I see there's no method unless I link it to a URL.
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: Where is the IAC located?

Don't just replace the IAC, (often they can just be cleaned out). You will need to clean out the IAC passage in the TB as well, if the IAC is gummed up.

Someone may have adjust your idle up using the screw on the TB, (BTW this really isn't intended for raising or lowering the idle, as raising it up take idle control from the ECM) A scan tool can help you diagnosis this but seeing it the IAC is out of range when at 1300 rpm.
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: Where is the IAC located?

I don't know the exact procedure for our trucks but you can do it with a scan tool (your essentially putting it a range the ECM can adjust). With the truck fully warmed up and in low idle, I would adjust the IAC steps to ~10-15.
 
NecroWolf

NecroWolf

lost marbles member
Re: Where is the IAC located?

you could just adjust the ear that comes in contact with the screw... not quite as precise but it works
 
S

s-crazy

New member
Re: Where is the IAC located?

Ok, I pulled the electrical connector off what I believe to be the IAC which is located in the back of the throttle body and pretty much under neath the hose connecting the inlet and the cooling component. I started the truck and it will run, but at a high idle (2000-2200 rpms). I guess I will try to remove the IAC after the truck cools down, clean it and see if it takes care of the problem. A while back ago, I did adjust the idle screw, because the truck would stall once in a while when I would engage it in drive or reverse, but only when it was hot. I figured I'd tweak it up just enough to keep it from stalling. It was fine for 6 months, until now. I guess we'll see if the IAC is the culprit. Thanks for all your feed back so far!
 
S

s-crazy

New member
Re: Where is the IAC located?

Ok, I replaced the IAC. I performed the task to reset the IAC by jumping the 2 ports on the ALDL. Turned the key to on for 30 seconds and I could her the IAC spinning. I turned off the ignition, pulled the jumper from the ALDL, and then pulled the ECMB fuse out and replaced it. I cranked the truck, but it would not start on it's own with out the assistance of starter fluid. Once I got it started, it ran fine, but idled high. I adjusted the idle screw down a little and it ran fine for several minutes. As soon as it started warming up, the idle slowly dropped and as soon as it got close to 1000 rpm, it would die. Once it died, I could not start it back up, unless I sprayed starter fluid down the inlet. I can keep it running as long as I want, but as soon as it gets around 1000 rpm, it dies. Why will it not start on it's own? I checked the rail and it was getting plenty of fuel pressure. I'm assuming if it was a fuel pressure issue, it would not run at all once I got it started, because I can keep it running as long as I want as long it doesn't fall below 1000 rpm. The EGR looked good when I pulled it out. It almost sounds like it gets starved for fuel around 1000 rpm and dies. I'm going to get it started and watch the fuel pressure at the rail to see if it drops at any time while it's running. This is sooooo much fun trouble shooting these babys! I need to get a laptop and analyzer if I plan to keep this baby for a long time which I plan to do since I want to keep it. Thank God for these forums! :D
 
HotRudyRod

HotRudyRod

New member
Re: Where is the IAC located?

I was having the same idling problem with mine, i took it to this shop to get it serviced since i knew spark plugs are a pain to change and need some special elbows to remove the ones in the back. I picked it up and it was idling fine, next day i started it and same problem. Took the IAC off and saw the damn mechanic had just cleaned it up and installed it back up (it had carved a groove in the very tip and it was gettin stuck open on the TB flaps), i went back pretty fired up and made him give me my money back. I bought a new IAC and it works fine now. I figure im gonna have to replace those spark plugs too as i dont think he even bothered.
 
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