Track1LE

Hi all looking for my next step in this headache. I swapped a LM7 into my C10 back in February and it was running great up until about a month ago. Started running rough only code P0300 random misfire. AT first it was just cylinder 3 & 7 now all of bank 1 is dead i can disconnect the coil harness and it does not effect the engine. Below is the diagnosis steps i've taken so far.

swapped coils, plugs, and wires
checked for intake leaks with carb cleaner
checked compression all cylinders @ 150psi
swapped pre cat o2 sensors
removed valve cover bank 1 nothing stood out
swapped injectors
checked injector signal with noid light
check power to coils
checked spark with a spare plug

Everything checked out problem is not found yet. Next up is i'm trying to find an ECU to swap i'm at whits end. Anybody seen anything like this before? Thank You

Track1LE

forgot to mention fuel pressure is good too koeo @ 60psi running @ 60psi

sowbelle

You mention pre cat o2 sensor
Do you have a cat on each side? If so is that one plugged?
Any other obstruction in the exhaust for that side?

Track1LE

Yes cat on each side i used the stock manifolds and cats from my '14 1LE they were essentially new when put on as i put LTs on as soon as i got my camaro. after each cat is just a dump, its easy enough to remove the cat i can give it a try or i might be able to get a backpressure gauge from work

sowbelle

or switch cats?