Hey guys sorry to ask for help with my first post but I just picked up a 06 RXT that wasn't running and have a couple questions. Story I got was it was in the shop for quite some time and they concluded that the ECU was bad but didn't have another to test with. It looks like they had the S/C off, Fuel Line was off at tank, Muffler and So on...

I charged the battery when I got it home and tried to start it. It had a mini backfire that was quiet and sounded like it came from the middle of the engine. Then there was the explosion. It destroyed the ABS resonator and my ear drums. I'm planning on tearing the engine down to see what damage that explosion did internally. Could something like that bend a rod? I might try to get away with just a top end rebuild if possible. It turns over fine. With all the plugs out, seems like it mist's out some fuel. I could not find a FP gauge to adapt to the test port. I also need to pick up a compression gauge that fits. 0-2 on the autozone loan-a-tool program.

#1 - I took the valve cover off and noticed where the water jacket bolt's bottom out, decent size chunks are missing inside the head, exposing a small part of the bolt. Is this common? Did someone over torque the water jacket? It looks like most are either cracked or chipped. Do I need to replace head? Have them welded up? Don't worry about it?

#2 - Is there anyway to test the ECU for correct operation? I'm thinking its either out of time or could the ECU cause the backfire? They replaced a sensor, can't remember if it was the crank or cam. The Cluster did not display any errors. Sometimes it does a different beep pattern when I put the key on and it will not crank at all, can't remember if it was 2 or 4 beeps. Might help explain a bad ECU? I could not find info on what said beep pattern was for.

#3 - Can/should I test some things before I take the engine out and tear it down?

Thanks in advance and sorry for the lack of info. Let me know if you need any info as this is my first PWC. Been waiting forever to find the right time to jump in!