Oscillating Idle...

[dobie3]

encountered after placing shift in Park. Essentially, the idle fluctuates between 800 rpm (normal) and about 1500 rpm several times before settling at 800. At first, I thought I had my foot on the gas, but now I realize it's the car.

Any thoughts as to why? Solution(s)?

Thanks,

[Joe_Black]

Mine does this occassionally as well, just haven't got around to asking about it.

[Moncha]

One semi-common problem could be the intake manifold gasket.. Those that have had that problem can answer to that..

[HotFlyer]

Mine just started that too.

[VX1]

Happens to me too, just every once in a while, maybe once in a couple of months. It's been like that for years with no ill effects.

[Navigator]

Mine does this when the temperature outside is above 85 and the humidity is over 80%. I think the VX is choking on smog like the rest of us. Issue goes away when the temerature and humidity drops below those levels. I doubt if it's anything serious, it does go away.

[Joe_Black]

LOL! That's like 95% percent of the normal weather here!

[Navigator]

I love it there, but man is it ever like a sauna July 4th weekend I am there like clockwork, does it get much hotter than that? Anyways, that issue only arises on bad air days here in MD, I think you guys have better air quality there, but definately more heat and humidity LOL

[Joe_Black]

Jul 4th? Hot? Nah, we're just coming out of Spring at that point. Come down, say, around early September. That'll charge your batteries! As a Florida native, my sinuses freak out if the relative humidity drops consistently below something like 60%. Trips out West always take weird "climatizing" turns! LOL! Don't even get me started on cold! I've spent too many Christmas visits to Alexandria and Thanksgivings to NYC for that! No no no... sun sea and sand for me please!

[andy454]

Could also be a dirty idle air control valve. If it gets gummed up with carbon then it can't react fast enough and may overshoot and undershoot. Simply remove the valve from the throttle body and clean with carb cleaner. Also clean the air passage in the throttle body. Could be the intake gasket as well. See my post on how to check for a leaking gasket. just use some carb cleaner and spray around the intake. If there is a leak you should hear a change in rpm.

[iownvx]

Mine did it first at less than 1000 miles. So I'd dount if it is dirt.

[dobie3]

I'll follow advice and keep you posted.

[Joe_Black]

Yeah, mine's done it since it had 16 miles on it. I've had the same thing happen with my '95 Trooper Limited with the 3.2L DOHC. Changed the PCV with next tune-up and checked all seals with nothing showing up. So when it happened on the VX I poked around and couldn't find anything obvious either.

[Jolly Roger VX'er]

Just a thought....are all you guys experiencing this with the air conditioning "on"....just wondering if the load on the engine of cycling the compressor could be affecting your idle....

I also know that on some cars the air conditioner compressor has an idle control module....don't know if the VX has one...but just a thought....

Honestly don't run my air conditioning much at all but the few times that I did I thought I noticed my idle speed vary along with compressor "load" which I took as normal.

Hope this gives you something to go on!

[AnalogVX]

Originally posted by Jolly Roger VX'er
Just a thought....are all you guys experiencing this with the air conditioning "on"....just wondering if the load on the engine of cycling the compressor could be affecting your idle....

I also know that on some cars the air conditioner compressor has an idle control module....don't know if the VX has one...but just a thought....

Honestly don't run my air conditioning much at all but the few times that I did I thought I noticed my idle speed vary along with compressor "load" which I took as normal.

Hope this gives you something to go on!

Good point. I noticed the same.