I hop in the stang yesterday morning to head to work when it starts idling rough right when I crank it. I always let it warm up about 45 secs or so, so I sit there listening. The idle stays rough, starts shaking the car. The CEL comes on, and I pull out my SCT2 to read em. It gives me P0301, P0303, and P0300 which are all misfire codes. I call the Ford dealership for an appt, but it's not gonna be til Tuesday that they can get to it.

The car is slightly modded with a JLT cai, sct2 tune from Brenspeed, UD pullies, and bassani cat'd xpipe with some bassani axlebacks. I plan to put the stock airbox back on and reflash to stock before bringing it in. It seems like some fouled spark plugs, but I don't use octane booster and always use name brand gas. I know there's a TSB about coil packs rough idle and hesistation which is what I think it may be. I'm scared they gonna try to give me the runaround because of the couple performance mods, but I'll cross that bridge when I get to it. Has anyone experienced this?

 

I've experienced rough idle, stumbleing, and smoke upon startup only once in a great while, although I've never gotten any engine codes. Here's the problem that I'm referring to: http://forums.bradbarnett.net/showthread.php?t=58616

I don't know if this is the same problem as yours or not.

 

I too have that had happen on a rare occasion. Now it idles super rough, doesn't get any better after warming, and has a strong gas type odor. I've reflashed, unhooked the battery, etc, to elminate it being computer based. I'm tempted to buy some new plugs and change them out to see if it that fixes it.

 

Sounds like you're right- either a misfire problem or its getting too much fuel for some reason. Good luck getting it fixed.

 

I've had this problem as well. It only happens when I don't crank the engine over enough to start it and then immediately try again. It's a fuel issue IMO.

 

check the plugs and wires

 

Last time I saw misfire codes I had two cylinders with broken ringlands....

Your not forcefed so I doubt thats your problem.... might just be bad plugs.

flash stock tune and put the stock intake back on... change the plugs and reset the codes and see what happens. It's possible you got a batch of bad gas with some water in and it screwed up your plugs.

My neighbor put gas in her car and it wasnt the best gas and a couple of her plugs got messed up, so i changed her plugs and coil packs and reset her Passat's computer and it ran fine afterward.

I think it's bad gas like ^ said....