97LT4

I'm completely befuddled at this point!! This car is having a hard time cranking over and I have no idea why.
I have 1997 Z28 with an LT4 kit (cam and 1.6 roller rockers), exhaust and intake. All mods installed 10+ years ago. I put the car into storage about 5 years ago. 2 Years ago I took it out of storage in hopes of driving it again and of course the car wouldn't start.
I tested the opti and it was bad so I replaced it with an OEM one. Car cranks fine at this point but still no spark. So I replace the coil and ICM. Still no spark.
At this point I figured the computer had failed so I took it to GM. Suspicion confirmed. Computer had failed so they replaced it. Still no spark. They replaced 2 connections that had corrosion on them and also the coil wire due to corrosion.
At this point the car started but they had fried the starter and the battery was weak. I brought the car back home and installed a new starter as well as new battery. Now the car seems to have trouble cranking over like something is stuck or tight ( i think it's out of time). So I jack the car up and jump the starter using a jumper pack with the car off. Starter and engine spin freely. I go to crank the car over via the key and the tightness/kickback returns. I try jumping the starter again and there's no issue. Finally I turn the key on and jump the starter and the tightness/kickback returned again.
So at this point I'm heavily leaning towards the car being out of time but I'm not sure how it happened or how to fix it. I did replace the opti but I'm pretty certain it was replaced properly. I didn't have to force anything together.
Any input would be greatly appreciated.

Thank you!

Injuneer

If it starts and runs fine when you start it by shorting the starter, not likely it's out of time. Sounds more like a power supply problem or problem with the ignition switch, or a component between the ignition switch and the starter.

97LT4

It doesn't start when jumping the starter. The engine spins freely but does not start when I jump the starter with the key off. But when they key is on and I jump the starter the engine does not spin freely.

Injuneer

I read that to indicate the starting problem had been solved. Apparently it has not been solved.

If the engine spins freely when you apply 12V directly to the starter, even if it doesn't start (which it wouldn't do with the key in the "off" position), the fact that it seems labored when you use the cars ignition switch/battery/wiring, does not confirm a timing problem. It indicates a power source or wiring problem.

That is not to say that the failure to start is not due to misalignment of the Opti.

Does it even attempt to start when you crank it with the car's battery - a few sputters, or no sign of life at all?

Does it still produce a spark?

Have you scanned the PCM for codes - there are a couple, for the Opti cam position sensor and the ICM that do not turn on the SES light?

I really think you need to address the power problem. A starting system that's sucking up all the available power, and still not turning the starter vigorously, robs power from the ignition and injectors. What does the dash volt meter read when you try and crank it with the switch/battery? What happens if you attach the booster battery in parallel with the car's battery and try to start it?

97LT4

I guess I should've said it started for the dealer. When I got it home and replaced the started I was able to get it to turn over once but it ran pretty rough so I shut it off after a few seconds and it was very difficult to get it to turnover. I had assumed this was due to having the stock computer settings again. (My old computer that failed was programmed for the lt4 kit etc...) So I got the new computer programmed for the LT4 kit and I haven't been able to get it started again.
I had LT1PCMTuning do my computer so I'm pretty confident that it's not the tune that caused it. If anything it made me lean more towards it being out of time since it got worse with the tune.

I will try the stuff you said above and report back.

Thanks Injuneer!

LT1_383_Stroker

While cranking then engine make DC voltage measurements across the following points:

Battery(+) and Battery(-)
Battery(+) and starter solenoid (+)
Battery(-) and engine block

The first measurement will give you an idea of how much the battery voltage sags under load.

The second and third meaurements will test the voltage drop across the battery cables. If either measures significantly high, you have a bad cable. Rock Auto sells some pretty decent replacements from AC Delco.