most confusing!

[younggun7187]

hello. im currently building a tube frame car sporting a 97 vette powerplant, completely standalone, throtle by wire, . brand new ECU and custum harness. it will not run on cylenders 5 & 6. fuel, air, and spark are all there. also passed compression and leakdown. any ideas?

[younggun7187]

oops i meant 4 & 6

[markzman97]

plug wires swapped around?

[younggun7187]

iv swapped everything there is to swap. coils, injectors, wires. cant get the misfire to move.

[markzman97]

I mean do you have the 4 6 pulg wires in the wrong place, switched with each other.

[0rion]

was the motor tore down prior to installing it? How many miles are on the motor? Seems like a weird situation and the only thing that I can think of right now is maybe bent pushrods or something along those lines? I'd hate to send you on a wild goose chase so don't go tearing the heads apart on my account. That's just the best guess I can come up with at the moment. 2 and 8 aren't showing misfires? Just the middle cylinders? It also sounds like you've covered most of the bases I would have by now so I'm kinda at a loss.

[TransAm11973]

does this sound like ecm to you guys? i mean if everything that he said is there is, then could it just be the computer f-ing up, or connections??

[younggun7187]

no 2&8 are doin fine. just the middles. sinse the first post i even went as far as trying a completely different set of coils. nothin! then i borrowed 2 more ECUs and tested it with both. didnt change anything! the engine hasnt been gone through at all, its out of a wrecked car. but we ran it at an event in october with a different modified loom and computer. the driver wrecked it into a wall. and as for the pushrods iv checked them all out on that side. strait as an arrow!

[0rion]

is the coil harness on that side of the motor a stock harness or did you guys make your own? The thing that gets me is you say you're getting spark and fuel so that makes me think that everything from the pcm to the plug is fine and that it's mechanical.

[younggun7187]

the coil harness is original, but i went ahead and back probed it anyway, everything was fine. i think im just gonna put it away for a while!

[0rion]

make sure you check stupid stuff too while you're at it. Make sure the plugs are ok and the ceramic isn't cracked or something stupid like that. Also go over the wires really good to make sure they're not cracked or something stupid. I know you said you checked everything, just trying to give some ideas. Most of the time in my experience it ends up being something really stupid that you've checked 10 times already.