Occasionally, when I go to start my engine, it starts up and then idles really low or stalls, unless I hold some throttle. Almost sounds like it's cammed. It has only done it on cold starts, so I'm assuming that it's my IAC valve sticking closed and not letting enough air in to idle. It really doesn't bother me much, because it happens very rarely and after holding the throttle for a minute or two, it'll idle just fine. I'm just curious if anyone else has had something similar happen, and what the issue was. The sound of the engine when it idles low is what has me most interested, because it sounds completely different.

Here's a short clip of it.

(Don't mind my red shift indicator, I have it rewired for a different purpose.)

 

Looking at your profile, it appears you have a 3.9 96 model?
Do you have a scanner that you could hook up? If so, look at the IAC and see if the counts are changing on start up.
Personally, it sounds like a miss to me.... How old are your plugs, wires, cap, and rotor?

 

Yes, I have a 1996 with a 3.9. I do have a scanner, but it's fairly limited on what it can read. I don't recall seeing anything about IAC counts. I could look at the manifold pressure when it's running rough, that would rule out or confirm my initial thought. My cap and rotor are brand new, so are my plugs, and my wires are fairly new too. I replaced them all just as a tune up a little while back, and this issue was happening the exact same before I did that.

 

Most scanners (not readers) let you look at each item in real time. If you can see the iac count, give it gas, then let it idle and see if its changing. It should if its working.

 

Oh okay, I guess my device would probably be considered a reader then, although it can still view some live data. I probably wouldn't be able to read the IAC count then, and also because I never know when it'll happen, and last time I didn't get my reader connected quick enough to see what's going on while it ran rough. If it happens again, maybe I'll try shutting it back off, taking out my IAC valve, wind it back a bit, put it back in, and see if it still idles low or stalls.

 

NO! Don't fiddle with the IAC valve itself!

Clean it, clean the passage, but DON'T wind it!

That's a sure way to damage it.

If you want to buy a new one, just buy a new (Mopar) one, and be done with it!

RwP

 

I see, alright good to know. I guess then, if it happens again, I could create a large vacuum leak and see if the idle improves.

 

I believe some of the parts stores have scanners that you can use. If you are monitoring the IAC counts, you should see them changing. Usually when you give the vehicle gas, the IAC count will drop. Then when it comes to a idle, it will go back up. I dont believe you need to catch the vehicle when its doing this. You can test the IAC when warm....

 

IDK if this will help but on the snap on MT2500 there is a option reset for the IAC.