no spark in cyl #4... only when in cyl head though? pull plug and its sparking?

[b00stinbmx]

ok so i started the car the other day, idled a lil rougher than normal and esp when reving up. pulled plugs... cyl 4 is wet. so i pulled the back 3 coil packs, put the plugs in and grounded them to the valve cover... #4 fired, spark looked identical to 5 and 6. tried a different spark plug, got the same results. I know its def not firing cause when i unplug it while motor is running i get no difference in sound/idle. I tested everything back from the ignitor. that checked out. tested power to the coil, tested ground. spark plugs are brand new about 1 month old.

the last thing i just tried before i gave up tonight is i pulled that #4 coil pack and cleaned the contact tip with some 1500 grit sand paper, inspected the whole thing, no tears in the boot or anything. Im stumped. it seems as if its getting grounded out or something when its in the motor and won;t fire, but when i pull it and turn the started over its firing perfectly... please help cause this issue is driving me nuts!

[Bluefire]

Maybe the #4 injector o-ring is shot and flooding the cylinder? i would also check compression just in case...

[Fibre guy]

+1I had a leaking injector and it gave me the exact same problem your having.Stumped me for the longest of times.