Rough idle/stall

[LSlayer]

Hello my Fellow Ford men,

I'm having an issue with my mustangs idle RPM. It becomes weak, erratic and eventually dies if you dump the clutch to aggressively or stall the car completely. If I try to restart it immediately, the symptoms persist for numerous start attempts unless I can raise the RPMs and get it to hold, or just wait an hour or two and even then its still hard to get it to start. Is this a fuel pressure issue? Here are the recent items change and maintenance performed:

Cleaned and oiled air filter
Cleaned MAF after I figured I over-oiled the filter.
Changed air filter, MAF and cleaned Throttle body
Changed Fuel filter, spark plugs(gapped within limits) and passenger upstream O2 sensor.(based on CEL code)
Had alternator and battery checked(within limits)

The idle issues really started getting bad after our cold snap set in a couple weeks ago. If I go start and drive it normal no issues. But if I let the clutch out to quick or stall it, then I'm in trouble. I do get some white smoke at first when I try to restart, but it doesn't last. Any sound advice is appreciated.

I posted in the similar thread below but didn't get any replies. Thanks

-Tim

 

[BruceH]

I'd suspect the tune isn't optimized for cold weather. Believe it or not sct has the base tune values pretty rich with a cold motor. Some tuners account for it and some don't. I've suffered exactly what you have going on and it was fixed by adjusting the cold motor fueling.

 

[LSlayer]

I've ran EVOs tune for almost eight years in colder weather and never had an issue. Is this something we can adjust on our handheld? After I changed the O2 I re-loaded the tune just to see if that helps. Maybe Ill give Fred a call and see if he can do anything for me.

 

[BruceH]

I've ran EVOs tune for almost eight years in colder weather and never had an issue. Is this something we can adjust on our handheld? After I changed the O2 I re-loaded the tune just to see if that helps. Maybe Ill give Fred a call and see if he can do anything for me.

If it was fine before then it's not the tune.

 

[ClassJ]

How did you clean the throttle body? Did you remove from the car and get it nice and clean? Sounds like an idle air control issue and that is all throttle body related.

I had similar symptoms that went away after a really good TB cleaning

 

[ClassJ]

Also trying another MAF may not be a bad idea, and make sure there are no leaks downstream of it.

 

[LSlayer]

I Did not remove the TB, but I will to see if it's gunked up at all.

 

[JeremyH]

Something to consider.

http://www.s197forum.com/forum/showpost.php?p=218817&postcount=79

 

[o2sys]

Vacuum leak maybe? I had a similar issue after my pd blower install. Had rough idle, the car would drive but would stall when I came to stop. And the car kept rising the RPM to compensate for the lack of vacuum.

I bought a cheap boost/vacuum gauge and hooked it up to the PVC hose and was reading -5 to -10 (fluctuating) which was not enough,normally it needs to be -20 Hg/in. Also my wideband was reading full lean during idle.

So I used the old cigar smoke test and found my leak and problem was solved. Previous to this solution me and my tuner were thinking I had a bad frps or maf or injectors or something but it was simple vacuum leak.

 

[skwerl]

I had a bad coil which was creating an intermittent miss. Didn't even throw a code but I found it by unplugging the coils one at a time while the car idled. Once I found the bad cylinder (idle didn't change when unplugged) I swapped the coil with one on the other side of the engine. The miss followed the coil, so I replaced it and the miss is gone.

 

[DAN 05]

Glad it was a coil and not something like a broken timing chain guide.

 

[LSlayer]

How did you clean the throttle body? Did you remove from the car and get it nice and clean? Sounds like an idle air control issue and that is all throttle body related.

I had similar symptoms that went away after a really good TB cleaning

I removed the TB and cleaned as best I can. I think it worked. I haven't duplicated the condition by stalling the car but it idles a lot better and doesn't want to die out when I let out the clutch like before. Thanks Class J!

 

[GTstang06]

Did you try replacing the throttle position sensor? I had an issue similar to this and I swapped out the tps sensor and I was good to go.

 

[ClassJ]

Glad to hear!