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Timing

I have a93 olds 3800 acts like its out of time , but after tearing down to timing chain I found it was not. car was running a little rough one morning and after driving approx. 20 blocks she shut it off. it never started again

Check for spark with timing light or spark checker.
Check fuel with starting fluid, spray with straw into throttle body or carb.
Commpression check should be next.

it has spark as it fires, tried starting fluid got extreme backfire. it fires back in muffler giving it the sound of firing late. how dow you use timing light on system with crank sensors? wondering if starter control module could cause it to sound out of time? or if the crank sensor can be tested,since I already have it off

There are so many possibilities, such as burned/warped valves, or a failed component in the ignition system. (what kind of ignition system is it? does it have a magnetic pick up in a distributor with an igniter? or is it completely electronic?) If the former, it could be a stripped distributor gear or a sheared gear pin. If the later it would be a part replacement at best. Do a compression test, and while you have the plugs out, put a timiing light on it and see if the spark is in time with the no. 1 tdc.

no distributer it has cam sensors and crank sensors and starter control module all electronic.

I suppose that you mean that the timing marks still align, when you say that it’s in time. Check for a WORN timing chain: turn the crankshaft with a wrench, and observe how many degrees it turns before the camshaft begins to turn.
You can check timing. The repair manual will instruct you. Clip a timing light to the #1 spark plug wire, and check against timing marks you have put on the cam and crank pulleys. It doesn’t have to be exact; just close.
When you say it backfires, do you mean it backfires back through the intake, or down through the exhaust? Makes a lot of difference, which one applies.

it back fires out the exhaust,I find no timing marks on balancer pulley,when I rotate the crank shaft the timing marks come together right where they are suppose too. I am starting to believe the problem is in the electrical components