Andaloro99

The past few days I have noticed when I come to a stop in neutralmy RPMs rise to about 2,000, drops to almost zero, and starts to idle rough.My foot is not on the gas or the clutch.

I don't know if this is justme being oversensative, but it seems like it is riding rougher all the way through the power band. Anyone have any thoughts? The car is a V6 manual with K&N CAI and dual GT take-offs with custom H pipe.

Thanks!

DelStang86

I have the same problem, and I have no idea what's wrong with it.

Andaloro99

I don't know if it is just a quirk of the car, or if something is actually wrong. Do you have an intake or exhaust on your car? My concern is that it has to do with one of those things, or at least I'm concerned the dealership will try to blame it on one ofthose things.

Ken Rogers

I think it's normal for this rise in RPM, but I don't recall the reason why. Could it have something to do with the power brakes needing a higher RPM?

Ken

Erdrickk

thought I recall someone saying something like it does it to burn off the extra carbon or exhaust or something like...some sort of emissions control thing

Ken Rogers

Have you recently disconnected your battery? The computer might be having to re-learn the idle setting after losing it's memory from a disconnected battery. A mechanic friend of mine told meit can take a car several days to re-learn, and theissuecan beworsened by a dirty throttle body.

Bandit111

The thing that bothers me is the part where you said rpms drop so low.I have an 07 and it was doing the same thing and idling rough at stops.I even took it to a dealership it was getting so annoying about a month ago.Of course,i put my stock filter back on and detuned,haha.

Anyways,i have yet to know what the problem really was.Ford said it was just fine,and you know what,it was...after i got it back i have no problems even with xcal and tune.They said they did nothing to it except run tests.Humm.The rough idle and rpm drops to almost stalls have gone away totally.

Some ideas.

>Dealership said have throttle body flushed every 15k miles
>try some different gas
>let them look at it and it will fix itself,lol

wolfey2k

I'd try resetting the ECU. Disconnect battery for 15 mins. then reconnect.
See if that takes care of it.
The symptom sounds very similar to a clogged and or failing idle speed control valve.
Our late model stangs don't use that method.
There is still an EGR valve though.
If the EGR valve sticks open at idle, even a little bit, that can cause one of your symptoms.
Of course it could be getting told to do that for some reason too due to some other malfuntioning sensor.
Could be dirty and sticking.
Without my knowing how many miles are on your car I can't really tell but if it's been a while since you've had regular maintanance, then it could just be crud getting on the throttle valve or crud buildup in the EGR ports.
I'd find and clean all the crud out first then go from there.
Also check for any vacuum leaks. A vacuum leak will cause all sorts of weird problems.
The high idle then it almost dying indicates a vacuum leak is a potential cause as well.
Anything that causes more air to be taken in than is supposed to be will cause the engine to idle up then fall almost dead as the system tries to compensate.
Hope this helps you figure out what's happening.
If I come up with any other idears I'll let you know.
Wolfey2k

Andaloro99

Thanks guys. It hasn't done it for the past 5 days or so...it may have just been a bad tank of gas? The car only has 8,000 miles on it. I will let you know if it ever comes back. Thanks for the advice.

DragonPL

Yes it's a topic that keeps poping up here on the forums all the time, Looks like it's a normal thing something to do with the O2 sensor, the only solution I found iswhen stopping to go to nuteral right when the RPMs in what ever gear you're in areas low as they can be before stalling, and not to -roll down- hills in neutral but in gear, because that same reving thing happens,