Car can't drive when cold. only once warmed up. Misfiring when Warm....

[JakeP]

Does it ever bring up a check engine light? if so, what code?

[immajackuup]

o2 and idle control valve is bad.

[dkbmxer002]

i have the same exact issue and have for about as long as you.. i have tried quite a few different things as well with no luck...


one symptom that may or may not be related that i also see is after driving on the highway for a while (and i believe only in cold weather) the car will sputter when i floor it on the highway cruising.

[fiftytakedowns]

I get a 1271 engine code, which means coil 1 I believe, but I replaced with a coil on plug conversion. same code spit out.

brand new 02 sensor less than 5000 miles.

ICV is working, you can see it flip open and closed.

[fiftytakedowns]

fml

[JakeP]

lol. don't commit suicide yet. Maybe try checking the ohms on the DME temp sensor? unplug the ICV? Have you thought about posting this on m42club.com?

[Ryann]

As suggested above, I think you've got a vacuum leak somewhere. Find it. Check all hoses and gaskets that connect to the intake manifolds AFTER the throttle body. Also, injector o-rings.

[fiftytakedowns]

As suggested above, I think you've got a vacuum leak somewhere. Find it. Check all hoses and gaskets that connect to the intake manifolds AFTER the throttle body. Also, injector o-rings.

HMM injector O-rings. I do have the mustang Injectors in there.

[dkbmxer002]

why would leaks cause issues only when cold though...?

[JakeP]

Doesn't really make sense if it only does the crappy idle when the motor is cold. If it was in intake leak, it would cause a crappy idle all the time.

why would leaks cause issues only when cold though...?

I think we're on the same wavelength...

[jlevie]

why would leaks cause issues only when cold though...?

A cold engine needs a richer mixture. Even a small intake leak will lean out the mixture enough to cause problems. Since the DME is running in open loop mode while the engine is cold it can't compensate for the leak. Once the engine comes up to temperature the DME shifts to closed loop mode and uses data from the O2 sensor to increase/decrease fuel trim to achieve stoic conditions.

[dkbmxer002]

but then wouldn't it have the same issues any time it goes into open loop mode..

[fiftytakedowns]

why would such a aggressive fall on it's face occut during this situation, at the same RPM?
the RPM threshhold RAISES as it gets warmer as well.

[fiftytakedowns]

lol. don't commit suicide yet. Maybe try checking the ohms on the DME temp sensor? unplug the ICV? Have you thought about posting this on m42club.com?

they already gave up on it, I had a multiple page thread goin. I know multiple people are having this problem too.

[dkbmxer002]

yup. my guess was going to be either failed temp sensor or the maf was bad. haven't had time or money to replace either of them yet.