Okay guys it has been 3 weeks since I washed my engine bay and I still have a misfire/sputter while driving only (around 1800-2000 rpm's). It was really bad the first day. Since then it has been the same. I changed all cop's and plugs. I ran a scan with my diablo and no trouble codes. I have tried to get the check engine light to come on but it will not. Visably we do not see any vacuum lines loose or damaged. Any more suggestions beforeI head to the high priced Ford dealer? The car ran like a scald dog before I washed down the engine. Needless to say never again. 99 Mustang Gt.... Thanks for any help!

 

Oh yeah, its not as bad now as it was the first day but it is the same now as it was the second day. Just thought I would explain it a little better.

 

same thing is happening to me...around the same RPM...hope somoene can help us out...

 

bump...anyone? I assume that this prolonged exposure to this sputtering might lead to bigger problems?

 

Mine began doing this but it didn't have to do with washing my engine. The back of my intake gasket was leaking water and it got under my COP. I replaced the intake gasket and it took a few days to dry out before it would fully clear up.
Sounds like your problem might be a little different though. Just throwing another random option out there.

 

I had this problem, too, but likeTX97GT, mine had nothing to do with water. I must have had 1 or 2 bad COP's. After replacing them all (with new ones) and the battery it was gone. It was like that for about 6 months, before I finally fixed it.

 

Mystang, if all your hardware checks out, like COPs, plugs, andinjectors for your 99 GT I would try TSB 01-01-09, an 80$ reflash to the PCM done by the dealer. Worked for me, and I have a 99 as well. The computer is just dumb in our cars thats the problem.

I'll refer you to my original thread:
https://mustangforums.com/fb.asp?m=4511996

 

My wifes car had the same problem. Spitting and sputtering, no check engine light and some days it wasbad and other days it was not so bad. it only sputter at low RPM's. it was her #3 fuel injector. a bad fuel injector will not alwaysthrow a check engine light. they will probably put it on the machine, charge you $85.00 and tell you that your not getting any fire to one of your cylinders.

 

if it was me i would pull your cops off shoot them with some compressed air to blow out any water and put a new set of plugs in it. try that or when it is skipping just unplug & plugin the cop one at a time and see which one is skipping.

 

How are you supposed to be able to unplug a cop and tell if it is bad? It doesn't skip unless he is driving it? Do you unplug it, then drive and see if there is a difference?