misfire cylinder 3, misfire cylinder 7

[Graham052]

a couple days ago I started up my car and it ran really rough, shaking the car, it eventually smoothed out, but I could tell it was not running right and the check engine light came on. I took it to advace auto to get the codes pulled; misfire cylinder 3, misfire cylinder 7. by now the car is running fine, but I unhooked the battery to get rid of the CEL, a day or two later the light is back on. I have not taken it back to get codes again but was wondering what might cause the misfire. I just replaced the plugs, so now I am thinking of new plugwires or plugwires and coilpacks
the car has ~64,000 miles

 

[Roger_4.6_96]

Time for New

1.Wires
2.Spark Plugs
3.Coil Packs

 

[smokin'Red35th]

what would cause the misfires?

 

[Go HoTO!]

I had similar problem due to being too lean with a MAF. I put the stock MAF back on to fix my problem. This does not look like the case with you, though.

 

[stangchef]

As much as you might not want to hear this...pull the JET chip and clear the codes and see what happens. My car would run great with that chip for a little bit and then it would run real rough and eventually die and wouldnt start back up. Remove the chip and everything was fine....I dont know why I sent it back about 4 times before finally giving up!

 

[Graham052]

ok, I will pull the chip after I get off of work and see what happens, the thing is that it is running fine right now it was just that one time.... but I still have the CEL maybe Ill have the codes pulled again quick to see what it is this time. I am also still planning on getting some plugwires too since they are probably due anyhow. thinkin MSD, any other suggestions or help?

 

[bdcardinal]

just a thought, are 3 and 7 companion cylinders? if so then the coil in which the wires are next to eachother is bad. Accel and MSD both make aftermarket coil packs. MSD, Ford Racing make wires plus other people im sure.

 

[Graham052]

just a thought, are 3 and 7 companion cylinders? if so then the coil in which the wires are next to eachother is bad. Accel and MSD both make aftermarket coil packs. MSD, Ford Racing make wires plus other people im sure.

yep. thats what I was thinking

 

[bdcardinal]

http://www.allfordmustangs.com/techarticles/firingorder.htm

looks as though they arent, but check to see that the wires arent crossed. its always possible.