random misfires under load

[Fosters]

Ok, i've been experiencing some random misfires ever since i washed the engine a long time ago. I've since taken out the coils,blew out any remaining water/dust, taken out the spark plugs (ngk tr55ix iridiums) they all look good, cleaned all the coil spring connector thing, still nada. It doesn't want to throw a DTC code/check engine light at all. I'm wondering if it is a bad coil, how i could go about testing them to find the bad one?? Symptoms don't happen when it idles or is driven slow, only when accelerating fast(er) than normal.

If not a coil, the only other option seems a vacuum leak of some kind. what's the best way of finding those? I only know of the PCV, egr and iac ones, any others that might cause this?

What else can cause misfires?

[mnstang]

anything can cause a misfire just about. fuel problem, compression problem, ignition problem, timing problem, etc. anything really.

i've got some cop coils wet on the inside before and it made them not work at all. i put them in an oven for a few hours on very low heat (150 or so) and it fixed them.

if it was a vacuum leak you'd experience your issues more at a lighter load.

you could get a good scanner and watch your misfire counters when driving to find out which cylinder it's happening, then switch parts from cylinder to cylinder and see when it changes.

[Sweet35th]

Ok, i've been experiencing some random misfires ever since i washed the engine a long time ago. I've since taken out the coils,blew out any remaining water/dust, taken out the spark plugs (ngk tr55ix iridiums) they all look good, cleaned all the coil spring connector thing, still nada. It doesn't want to throw a DTC code/check engine light at all. I'm wondering if it is a bad coil, how i could go about testing them to find the bad one?? Symptoms don't happen when it idles or is driven slow, only when accelerating fast(er) than normal.

If not a coil, the only other option seems a vacuum leak of some kind. what's the best way of finding those? I only know of the PCV, egr and iac ones, any others that might cause this?

What else can cause misfires?

The coils can carbon track very easily, and no extent of cleaning can ever make them the same again.

If you want to swing by the shop, I can hook up the WDS, and we can moniter real time cylinder missfires, do a power ballanced test under load, reletive injector flow test, ect ect.. Cost is $125 for engine diagnosis.. Could save you from throwing $100s at the car hoping to solve the problem.

[Fosters]

The coils can carbon track very easily, and no extent of cleaning can ever make them the same again.

If you want to swing by the shop, I can hook up the WDS, and we can moniter real time cylinder missfires, do a power ballanced test under load, reletive injector flow test, ect ect.. Cost is $125 for engine diagnosis.. Could save you from throwing $100s at the car hoping to solve the problem.

You only tune Diablo though, right? no SCT? just in case any changes need to be made to the tune; it's still tuned on phoenix terpentine... errr gasoline...

[Sweet35th]

You only tune Diablo though, right? no SCT? just in case any changes need to be made to the tune; it's still tuned on phoenix terpentine... errr gasoline...

Yes diablo. We are considering also geting the SCT software.