[kszmustang]

i have a 2004 v6 3.9 automatic the car has 150,000 miles and the transmission started to slip really bad and my motor was burning water and has a exhaust leak on the passenger side were the ac drains like most mustangs have so i got a used motor and trans that have 70,000 miles on them...the motor did not come with ac compressor,power steering.alt or coil pack so i used the ones off my motor..install went great no probs then the car ran great for a day (120 miles) i was drivinh about 55mph and it started to make a backfiring sound on the passenger side when i stoped and was at idel it ran very rough but one i got up to speed it ran better now i have a check enging light that says p0301 cyl 1 missfire...i have new plugs and wires and the prob is still there....one person told me its is my valves because of the exhaust leak and another told memy coil pack is dead on #1 is there a way to test the coil pack with out a ohm meter......PLS HELP

 

[Markstang]

if it were the coil pack, neither cylinders 1 nor 5 would be firing since they are paired and fire at the same time.. you can check for spark in cylinders multiple ways.. noid lights are one way.. you can also pull the wire while its running and hold it close to listen for spark, or see if the engine runs any worse.. if it doesnt, then that cylinder was misfiring... there are also a couple other ways I'm sure.....

did you use the factory routing of the plug wires and the standoff things that hold the wire from touching the block or anything metal?.. if it touches, it can still arc through the insulation and fail to ignite the cylinder

 

[kszmustang]

yes i did use the factory routing.... i pulled the wire and held it close i can see spark jumping on 5 and all the others but there is NO spark jump on cylinder 1