My bet it wasn't the misfire or backfire, but someone trying to rev past the misfire that gendered the engine.
I loved telling people to read the TM when I was Maintenance Chief. Now that I'm a civilian, I get to enjoy telling sailors to read the TM.I served our country too, in the same fraternal organization he was in. I, however was Motor Transport maintenance, ending up as an MT Maintenance Chief. I'm 74 years old, tell him an "old Corps" MT Maintenance Chief told him to read the damn TM (FSM) and do it the right way,
I highly doubt that the camshaft position sensor was reporting a bogus position to the ECU (engine control unit). It was just reporting what it was detecting. So either the camshafts were out of time in relation to the crankshaft or someone got the connectors switched between the intake cam position sensor and exhaust cam position sensor.. . . I think it was the Autozone sensors that caused the backfire and damage. I asked him to pull the timing cover and let me have a look at the cam timing and it's spot on. Dot to dot they line up along with the crank mark in the correct position. He said the car was running "okay" but was stuttering some. Had the codes read and the Zone genius sold him the cam position sensors. He said as soon as he put them in, it started backfiring. Can't prove it was the sensors, I'm sure, but I STILL think that's what caused the problem. . . . .
The sensor itself does NOT adjust the timing. It just reports the relative position of the camshaft to the crankshaft. Based on engine running conditions the ECU will pulse an electrically controlled solenoid and allow a certain amount of pressurized engine oil into the internal workings of the camshaft sprocket. This will either advance or retard timing of the sprocket relative to the camshaft which changes camshaft timing. The calculation for determining the amount of oil to admit and move the sprocket relative to its camshaft is done in the ECU software. As this happens the camshaft sensor is monitoring the advance or retard of the relative timing and providing feedback to the ECU.. . . .. . . Supposedly the cam position sensors automatically adjust the timing if it's a few degrees off. Personally, I don't see how a sensor can adjust the timing several degrees, but I've never claimed to be a mechanic.. . . . .
I would suggest to remove the damaged engine and set it along side the replacement. Compare the 2 units and look for any detail changes. Look at flywheel diameter and the offset at the hub for differences. Count the number of teeth on the flywheel and note any differences.. . . A couple of questions I have and haven't found an answer for is if we'll need to swap the flywheels and if he'll need to have a dealer flash the ECM. Reason I'm asking is he bought a low mileage engine out of an automatic and it has around 40,000 miles on it. His car has over 100,000 miles. His car is a manual shift.. . .
Thank you for your input AllanC. Much appreciated!I would suggest to remove the damaged engine and set it along side the replacement. Compare the 2 units and look for any detail changes. Look at flywheel diameter and the offset at the hub for differences. Count the number of teeth on the flywheel and note any differences.
I would think you would use the existing exhaust manifold mated to the damaged engine. Do the intake manifold match and appear to be the same? Look at the fuel injectors on the intake manifold and sensors and the throttle body. Is everything identical? This kind of inspection will go a long way to ensure this is a successful transplant.
Since you are NOT replacing the ECM and will continue to use the existing unit in the vehicle I would see no reason to reflash and ECM. Fuel management data recorded in the ECM for the damaged engine will be replaced and updated when you start and run the replacement engine.