Manybrews - need some help

[RED2KESV6]

I have a 2K V6. Recently when the engine is fully warmed up the idle speed in gear (at a stop) drops to about 500rpm, then increases slightly. Sometimes after dropping to 500, it will speed up to about 700, then drop back to 500 - erratic idle speed. When the low idle first started I did what everybody says to do first - I had the throttle body and related stuff cleaned, but that didn't help. Took it back to the shop yesterday where the tech did a troubleshooting flowchart. He said the IAC tested (ohmed) out OK. Found that the plugs (have about 60 K on them) were pretty worn - gap of .050, but the car runs fine other than for the low idle - no misfire. Tech said he can't be sure what exactly is causing the low idle, and I don't see how the worn plugs, although I will get them replaced soon, could be causing the idle problem, especially the erratic speed and the tech agreed. For now he adjusted the idle speed a little higher and I'll see what happens. Any other things that could be causing the low and erratic idle?

[WarmAndSCSI]

I haven't seen manybrews around lately... I'm guessing the problem is your IAC. It cannot be tested fully with just an ohmmeter: http://www.fast-4ward.com/3GsvcManual/13A.pdf. Try to find a used IAC and replace yours just to be sure.

[Galant306m]

could be a Cam positioning sensor. would be throwing your idle all over the place because it dosnt know the position of the cams.

[WarmAndSCSI]

^^ Except that would likely rear its head under load and you'd be getting some form of backfiring. He's looking at a problem with ONLY idle surging which will have specifically to do with the idle control system.

[GOOSEY2099]

^ I Concur

[boostzealot]

the iac sounds right in most cases but i remember having something like this happen a while back and it ended up being a very slight vacuum leak. under load it was fine and seemed to be normal but the minute i tried to let her idle it would drop like it was going to die and then would try to find its "happy place" but was having difficulty. i would while you are changing your spark plugs replace all your intake mani gaskets including the one between the tb and the upper intake mani and verify that all your vacuum lines for evap and other type of controls are in place and well sorted out.

[WarmAndSCSI]

^^ good point. Vacuum leaks won't affect anything once you get past idle.

[cdipier2]

that might be my issue too. although it doesnt do it all the time. it only goes down 500 sometimes, and other times it idles normally. i have a spare IAC im gonna switch it out, reset my computer and see what happens. i was gonna do it this morning but it was sleeting :lol:

[RED2KESV6]

I haven't seen manybrews around lately... I'm guessing the problem is your IAC. It cannot be tested fully with just an ohmmeter: http://www.fast-4ward.com/3GsvcManual/13A.pdf. Try to find a used IAC and replace yours just to be sure.

The link takes me to info for the 2.4 liter. Is the IAC check the same for the V6?

Thanks to all for the replies so far.

[WarmAndSCSI]

I haven't seen manybrews around lately... I'm guessing the problem is your IAC. It cannot be tested fully with just an ohmmeter: http://www.fast-4ward.com/3GsvcManual/13A.pdf. Try to find a used IAC and replace yours just to be sure.

The link takes me to info for the 2.4 liter. Is the IAC check the same for the V6?

Thanks to all for the replies so far.

The 3.0L MFI doc (13B.pdf) refers to 13A. I meant to post that.

[RedGalant2k1]

What is the car idling at?