Idle air control valve?

[bigdog379x]

Recently my 305 has been idling really speradicly on cold idles, jumping from 800 rpm to 300 rpm and stalling but only when the truck is in drive. If i put the truck in nuetral it will idle fine. Since i got the truck its always had a slight buck at idle in park, kinda like a cough out the pipes. Would this be symptoms of an IAC going bad or is it anything deeper than that?

 

[dkennedy]

If it is a 88 - 98 model engine and if helps at all, when my wife gets home I'll have her scan a page out of my book to show you how to check it with an ohm meter... although the IAC has to be checked with a scan tool to get an exact idea about the condition of the part's opperation, in the case of an IAC failure it will rule it working or not.

 

[bigdog379x]

Yeah its a 95 model tbi. And if you could do that, that would be great. Thanks.

 

[dkennedy]

You'll have to blow the image up in in your imaging program (Control+), but here it is... starts in first column on the right as it was continued from the previous page. The connector plug may or may not be the same as yours, and if it's not let me know and I'll try find the right one so you can test the wires correctly.

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[bigdog379x]

Well changed the IAC and no dice. Still does the choppy idle in gear but now its starting to do it when its warmed up and in gear. Any suggestions on what else it could be?

 

[K3500]

im in the same boat! as soon as i put my truck under a load in either drive or reverse i get some crazy idleing going on. i removesd my throttle body and cleaned the carbon buildup. then i did an oil change and put fuel system cleaner in it. then i just did a fuel filter. the fuel filter has helped it a little however it is still doing it sometimes instead of alll the time.... im gonna look into more on the fuel side of things....

 

[dkennedy]

If I thought I had a fuel issue, the first thing I'd do is hook a fuel pressure gauge to it and make sure there is adequate fuel pressure, then I'd and have someone hold the brake and drop it into drive and see what happens.

 

[K3500]

really, ill give that a try!! thnx

bigdog379x- did u try any fuel issues?

 

[Blue95]

Mine has a slight hiccup type miss in drive too or in park at a warm idle, I think my distributor gear is worn out