Hi All,

I know this question has been asked before but my 1998 Ram 1500 with the 5.2 L stalls when I take off the throttle, and before I start throwing some serious money at it I'd like to see if anyone here has solved it. What I noticed was it would idle fine but after taking my foot off the gas it would lug down to around 450-500 RPM and either stall or bounce back up. It would do this in park, reverse and drive. When I kept messing with it trying to keep it from stalling it sometimes wouldn't start right back up and I'd need to let it set for an hour or so then it would start fine.

Now I have already tried the IAC solution and did a thorough cleaning on my throttle body replacing the IAC motor. After doing this it seemed to run better for a day. I drove it around for a fair bit but then this afternoon I noticed when just lightly hitting the throttle after a a short, less than 1 mile drive, the engine bogged down to around 500 RPM and acted like it wanted to stall.

Could it be an issue with the computer or something????? Since after i reset it by taking the battery terminals off and it ran fine until it recalibrate after driving for a bit, or should the computer have nothing to do with this issue?

Also note that when I removed the throttle body there was no gasket between the manifold and the TB, not sure if this is an issue but I plan on putting one on. A big storm came in so I can't work on it for a day or two but plan on taking a look back at the throttle body and putting the gasket on.

Thanks for if anyone has any ideas!

 

What brand IAC did you install? These trucks really dislike aftermarket sensors in critical locations..... I replaced my IAC with one from the parts store, to alleviate the same symptoms you are seeing. It was *better*.... but, would still stall more often than I cared for... So, replaced the IAC again, with a spare Mopar unit I had on another motor. Problem solved.

 

I installed a "Original Engine Management IAC34" iac valve. One I found on amazon. Ill look around for a Mopar one then and hope thats it.

Do you know if theres any way to test IAC motors without a scan tool? I took the original motor out and cleaned it up good but after reinstalling it I still had issues, thus why I bought this one. Just would like to know if I can salvage it at all.

Oh and quick note too, I haven't had any check engine lights either. If it still is the IAC thats bad would it not trip the CEL?

Thanks I really appreciate the help!!!

 

Generally, they either work, or, they don't..... No way to test without a scan tool. At least, not easily.

The PCM considers the IAC a "pass/fail" part. If it controls idle speed when the PCM tells it to, then, all is good.... If the PCM tells it to change idle speed, and it doesn't, then, it's bad.

You run into problems when the 'new' IAC simply doesn't react the way the PCM expects. It opens/closes to fast/slow, or moves further per "step" than the PCM is programmed for. That's why you see swapping out the "new" IAC, for a Mopar unit, tends to solve the occasional stalling problem you get with the aftermarket units.

 

I think it's 12 volts to the IAC. 2 pins make it go out, 2 make it retract. It's important to try not to manually push or pull the plunger while it is out of the TB. That can damage it. Try 1 and 4 for one way and 2 and 3 for the other way

 

But keep in mind that it is very easy to shoot the pintle right out of the IAC.....

 

You watch your mouth young man!

 

Young? Ah, if only that were true.

 

Hey thanks for the replies guys, while I look around for a Mopar IAC valve I'm going to try putting the original back in the truck to see if I find any difference. Im also going to check the voltage going to the valve like you say.

Also do either of you have gaskets between your TB and intake manifold. Noticed i didn't have one so not sure if I should get one or not.

 

Yes on the gasket.