I have an 07 gt. I recently changed the spark plugs in my car. I ended up breaking them which sucked but I got them all replaced. About 2 weeks later while I'm driving down the highway at 70 mph, I get a flashing cel? and a misfire. Could the coil pack be bad. I didn't change it, just the plugs.

 

What's the code say?

 

It was a p0301 and p0303. Cylinder misfire at random. I bought a new set of coil packs, hopefully that fixed it. So far no issuez

 

What plugs did you put in?

Also, those 2 codes aren't for random misfires, they're for cylinders 1 and 3 misfiring

 

I would check the actual plugs and wiring before I went with new coil packs. Switch the plugs and coils and see if the code follows them. That we you can know for sure instead of just throwing parts at it.

 

The plugs I used are ford motorcraft. Autozone hooked up the scan tool and it showed 3 codes. P0300, p0301, p0303. He recommended that I change the coil pack. I did. My car has 119k on it and the plugs and coils were still original.

I changed the coil pack Monday morning. It's Thursday and I haven't had any misfire issues since. I also used a can of seafoam to clean stuff out. My car has accelerated better, and it seems to run better.

 

Yeah the original plugs are probably what was causing the random misfire and multiple-cylinder misfire codes.
When they get up over 100k like that, that's the sign you need new plugs, lol.
Of course, many people do them early, especially on the 3V engines, where they tend to break if left in there till 100k

 

dude I broke all 8 in the cylinders trying to remove them, it was terrible lol. Autozone gave metheir removal tool. Ever since changing the plugs and coil pack I haven't had a misfire issue. I've even drove it hard to see if it would do it but it hasn't. I think I'm just being very paranoid now