I have a 99 mustang gt. For the last month the check engine light has come on and the engine has run rough. I ran some seafoam through the intake and gas tank and reset the computer. Couple of days later the problem is back. I hooked up my scanner to it and it says #6 is the problem. So i figured it was a coil or a injector so I swaped them each to a diffrient cyclnder to and switch the other ones to #6. Reset the computer. Couple of days later light comes back on with the same problem and my scanner still says its number 6!!!!! Does any one no what could be wrong with my car? By the way the spark plugs are new and still good. And as far as I can see all the connections are all still good

 

What exactly was the code that you pulled?

 

I dont remember exactly im at work but I know that it was said cylinder# 6 missfire

 

I HAVE AN 03 GT AND MINE IS DOING THE SAME THING. FIRST TIME I CHECKED IT, IT SAID MISSFIRE ON 2 AND 4 SO I REPLACED ALL SPARKPLUGS AND RESET IT. IT CAME BACK ON AND SHOWED MISSFIRE ON 2, 4 AND 8. I CHANGED THE COILPACKS ON 2, 4 AND 8 AND RESET IT. IT CAME ON AGAIN AND SAID RANDOM MULTIPLE MISSFIRE. MINE HAS BEEN LIKE THIS FOR ABOUT 4 MONTHS. WHICH IT IS NOT MY DAILY DRIVER. I WASHED MY HANDS WITH IT UNTIL I SAVE UP ENOUGH TO TAKE IT TO A MACHANIC. IF YOU FIGURE ANYTHING OUT, LET ME KNOW AND I MIGHT TRY IT ALSO.

 

I've had several of the same problems months ago

coil packs

1 went and tripped light missfire #5

second went out with no CEL ended up being #6

Check your plugs while your at it (gap)

 

you say "rough" as in...it sounds like its misfiring, just loss of power, or its not idling right etc...can u give a better description?
but from what im getting, have u checked your fuel filter? Double check all your ignition, and make sure everything is tight (may be vacuum)...it could be your egr or pcv systems...check your ignition first, just throwing out ideas

 

when I say its running rough its hessitating and idles very rough to the point to where at times I have no power

 

Hmmmm im no mechanic but that sounds like coil to me

 

have u been runnin a lot of fuel additives? check ur plugs expecially #6 for build up or miscoloration