Engine problem???

[CHROMEDCRUISER]

I was sitting in a parking lot yesterday idling and the tachometer slowly went down from 1000 RPM to 500 RPM and I could hear the engine sort of putter. The AC was on low. I have a 20003 touring edition 5 speed. Anyone have any clues as to what the problem is? It's never done this before, but I'm worried that it may do it again. Any tips or suggestions would be gladly appreciated.

[quicksilverdon]

Had you just started? Perhaps it came off fast idle too soon. When I start mine cold, it'll idle at 1,000, then when it warms, drops to 750. 500 is low.

[KingKole02]

Sounds again like the common bad sparks plugs and wires. Your idler maybe set too low for some reason too.

[CHROMEDCRUISER]

Well, I had been running for a little while, about 10 miles, and when I parked and put the car into neutral, the RPM's dropped to 500. I have driven several times since and there has been no problem. Thank you for the replies, any more suggestions?

[milPT]

Sounds to me like your idle is a bit low (I know, I know, duh). Do you know anyone that is really good with cars? have them listen to it and they might be able to turn your idle up. Doesn't mean that your spark plugs and wires are bad, could be, but not always.

[dizzydevil]

I have a 2002 PT Limited. I have had a problem for about a month now. If I park it (warmed up) it will idle at around 1000RPM and then drop to 500 and come back. I also notice that it seems to surge when stopped at traffic lights. I bought it used it has 38K on it and I have had it reprogrammed by Chrysler Dealer at 32K for same problem in Oct. 2003. I don't think programming had anything to do with it. Since it has happened again. Any ideas?

Diz

[CREWZIN]

Diz,

Was the air-conditioning running or the fan switch on defrost (which also runs the compressor). When the compressor comes on the idle may raise to compensate for the drain in power and when the compressor shuts off, the idle may return to normal running (should be around 700 rpm's + or -).

[quicksilverdon]

Welcome, dizzydevil.
I'd put in wires & plugs. May not be the problem, but can't hurt & then you could rule them out. I went with Champion plugs & Crane wires (RaceAndStreet.Com) because I had a miss. Strictly speaking, if you don't get a spark , you should get an error code, but not always.
I'd do both plugs & wires, since you have to take intake manifold off, which is a pain, plus I had at least one bad wire before 40,000 miles. I'm now at 72,000+ miles, have not had a problem since plugs & wires.

[quicksilverdon]

Just saw this on another forum:
http://www.ptforums.com/zeropost?cmd=tshow&id=1757
Can't hurt to try disconnecting battery....[:I]

[dizzydevil]

Thanks for the responses. Yes the Defroster was on. But I have had it off before and it does the same thing. Kind like it surges and then stops and runs fine and then surges again. I will try the suggestion of the Battery and Plugs/Wires. I'll let you know what I find. I'm thinking it may be the IAC module... Anyone had experience with that?