2004 Chev Cavalier - Misfire 2 & 3?

[autoxperts]

changed plugs did not change running. changed coil pack and check compression is 150 all the way across. still has missfire.

any help would be appericated

[steven kiser]

Are you getting impulse to each injector? On side by side misfires i remove plugs and do a quick leak down check. On occasion i will get air out of the corresponding cylinder. Also check for impulse to the coil.

[Cory]

I would check into the ignition module, These engines had problems with those. If you remove the module you can use a test light to see if those cylinders are working. I believe cylinder 2-3 actually fire at the same time, so probably use the same trigger from the ignition module.

[autoxperts]

the injectors are pulseing good. they do fire at the same time thur the module,but i thought if module was bad it was bad and would not fire on any of the four

[autoxperts]

and leak down passed

[ricmorin]

I don't believe all the injectors fire at the same time on this engine. The coils fire in waste spark 1-4 and 2-3 pairs, but I don't think the injectors do.

Anyway, have you done a running compression test? How about an injector balance test? It seems coincidental that it's the 2-3 pair. Have you scoped the primary and secondary waveforms from the ignition?

[autoxperts]

yes compression test good,injector balance good. so in the module will 1&4 fire if 2&3 is'nt

[ricmorin]

Sure. It's possible.

I'd compare patterns both primary and secondary on ignition between the 1-4 pair and the 2-3 pair. You may find your answer there.

[jbadenoch]

Ive had quite a few cases where the module would not fire coil for a particular coil, simple way to check, see if spark is strong and present on all coil posts. good luck

[92zman]

I have had module not fire just a few plugs. One thing have u checked for spark.

[steven kiser]

yes compression test good,injector balance good. so in the module will 1&4 fire if 2&3 is'nt

The answer is yes it will, can, and does. Remember, if you're probing the coil for signal test both leads. You may have a broken ground wire instead of a power issue. Not 100% sure here but this may be a ground trigger. If it is then there is a 12 volt feed to the coil (so it can amp up) and the ground pulls the trigger. I've run into so many different ground issues causing so many different issues it's mind boggling. I feel like Homer Simpson pulling at that last hair.

[autoxperts]

it was the ignition module. fixed thanks for all the help