Thread: Idle fluctuation and stalling when put into park? Trac light on?

For a few months I have been noticing when I put the car in park, most of the time but, not always the idle will drop real low and then come back up and it will teeter tot back and forth about 3 times before coming to sit where its supposed to be. Tonight though I pulled home and put the car in park but left it running and after a few minutes of it idling totally fine out of no where it starts stuttering and then it will recover and it'll go back and forth until it finally stalls unles I give a little push on the gas. I should mention that after it stalled the traction control light was on and not turn off able. I was also watching my wideband the whole time and it was really weird because when it would start stuttering the afr was dropping into the low-mid 12's. Any ideas what this could be?

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Bump still kind of an issue. It Hasn't stalled recently but ive still been having really weird intermittent idle where it'll go rich and then lean. Etc etc

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sounds like it needs a maf adjustment, probably the tcs is something different.

Originally Posted by SgtMarshal

sounds like it needs a maf adjustment, probably the tcs is something different.

Tcs? Torque converter?? Well all the sensors seem to read pretty normal all though i did add the nitrous tb spacer around the same time I started noticing it. What's weird though is how it seems intermittent which is why I don't think its just a vac leak.

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Hm... strange. Maybe the ait sensor since it's getting cold?

And no codes whatsoever? Have you checked the fuel pressure just to be sure?

Originally Posted by wstefan20

Hm... strange. Maybe the ait sensor since it's getting cold?

And no codes whatsoever? Have you checked the fuel pressure just to be sure?

It doesnt seen to be the iat, that sensor is also reading normal.
I haven't checked fuel pressure although I doubt that would be an issue when I can go WOT with no issues.
My current tune has all the check engine codes turned to no reporting so I have no idea if I have any. Ill reflash a tune tomorrow so I can get the reporting back.

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traction control system

edit for more info:

mine does the same thing, except the rpm's dont drop down very low, I can watch the afr go rich and the idle will get rough.

Originally Posted by SgtMarshal

traction control system

edit for more info:

mine does the same thing, except the rpm's dont drop down very low, I can watch the afr go rich and the idle will get rough.

Its not supposed to do that though right? Maybe the car doesn't like having the plugs gapped so small. I read somewhere that a smaller plug gap can cause a rough idle?

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I've heard a malfunctioning abs module can sometimes cause erratic rpm like this because it is a pass through for the vss data. I'd be curious to know if there are any abs codes, and if not, what the live speed sensor from each wheel looked like.

When I had a problem with my module, one wheel would bounce from 0 to 80 all over the place and my traction control and abs would go haywire!

Probably not the problem, but I'm just curious why the abs light is on.

start engine.. lift hood...tap maf with finger. Anything different happen? If yes.. time for maf

Originally Posted by Scottydoggs

my top swap hated a spark plug small gap. 0.50 works best for me. felt like the engine was misfiring all over the place, idled ok tho.

Well I regappes my plugs at .35 for the nitrous. It seems to run perfectly fine in normal cruising at wot situations.

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Originally Posted by BillBooost37

start engine.. lift hood...tap maf with finger. Anything different happen? If yes.. time for maf

Ill try that when I get off work. I have 2 spare maf if that's the problem.

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Whenever I had a similar issue..I'd pop the hood, tap and presto I knew what the issue was.

Originally Posted by wstefan20

I've heard a malfunctioning abs module can sometimes cause erratic rpm like this because it is a pass through for the vss data. I'd be curious to know if there are any abs codes, and if not, what the live speed sensor from each wheel looked like.

When I had a problem with my module, one wheel would bounce from 0 to 80 all over the place and my traction control and abs would go haywire!

Probably not the problem, but I'm just curious why the abs light is on.

Well the abs light isn't on. Only the Trac off light. Although I havent had that happen for a while and it only happened if the car actually stalled.

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Originally Posted by suitercrew

Well the abs light isn't on. Only the Trac off light. Although I havent had that happen for a while and it only happened if the car actually stalled.

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Interesting... if you end up needing a maf sensor though, I've got a spare oem one lying around here somewhere... that is if I can find it...

Just to update the SOLUTION was replacing the upstream o2 sensor for the 3rd time in a couple months. Never ever buy bosch oxygen sensor.

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