97rebuiltZ28

First off I rebuilt this Camaro and have had it running for about 4 months now. I’m about to sell this car and want it to at least be running alright before selling.

The rebuild included new opti, new plugs, plug wires, coil, and icm. All parts only have 2k miles.

So I was driving the other day and it started having what felt like a “rev limiter” at 3k rpms. The next day I tried to replicate that and it ran perfect until it got to temperature and died.(I figured it was probably the ICM) It would start back after setting for a few minutes but would die after a few seconds. I drove it home today(5 days later) so I could replace the ICM and it made it home, *it never got to temperature so it ran fine.*

I just replaced the ICM and it started for 3 seconds and died and now won’t start back. What’s up with it???

Note: It is an Autozone ICM and I had a warranty so they replaced it for free. They said the old one tested to be okay but the test isn’t always 100% accurate.

Injuneer

Can you scan if for codes?

What happens when you turn the key to "start"? Starter cranks engine? Engine show signs of attempting to fire, or nothing? Have you checked for spark at the plugs? Can you check the fuel pressure? What does the "SECURITY" light do?

What brand is the Opti?

97rebuiltZ28

When you turn the key to start it does crank but does not seem to fire. The only code is P1371. Opti is an autozone opti. Just about all of the parts were bought there. The security light seems fine. And I can’t check fuel pressure here but it seems fine because when I replaced the fuel pump it ran horribly and it runs really smooth when it runs. It just won’t start.

Injuneer

P1371 is the most likely cause of your no start problem. It is set by failure of the low resolution cam position signal from the optical module in the Opti. And it doesn’t turn on the SES light.

When P1371 sets, the PCM shuts down the fuel system. The pump will still prime for two seconds when you turn the key to "run", but it will not continue to run, and the injectors will be turned off, unless the PCM receives the low resolution pulses from the Opti.

97rebuiltZ28

*Update* I let it sit for a few hours and it started right up. Ran great like it always has. It hit about 175-180 and it died. No warning. Here is is a video of it running fine other than the squeaking belt. Skip to the last 30 seconds to see it die. Also in the video about halfway through I show all of the different data in the computer on my car.

Injuneer

Shows you have one code when it’s running. Did you clear P1371 earlier? Shows you have one code after it stalls. Same code?

Clear the codes and try again.

In one case one of the members here (author of Scan9495) helped someone with a problem similar to yours. He is able to run the Opti in his LT1 simulator. Heated up, failed. Opened the optical module, and found a sloppy solder joint in the Chinese module. As the module heated up, the joint opened up and interrupted the circuit. Resoldered the printed circuit board, Opti was healthy again.

In general, the less you pay for an Opti, the quicker it’s going to fail.

97rebuiltZ28

Thanks for all your help Fred! Yes that was the same P1371 code. It throws it every time it dies.

GaryDoug

You can confirm an Opti failure by just watching the tach while cranking after it has shut off. The needle should normally go up slightly but won't move if the Opti has failed. Watch for the 2nd crank in this video of normal operation. The first jump is just for the starter coming on.

97rebuiltZ28

I’ll definitely have to try that. Is it always an accurate test?

Injuneer

You have to clear the code after each event, or it will show up as a "stored" code every time you scan it. Are you doing that? It take a reasonably large number of "drive cycles" without the code recurring, before the PCM will self clear it.

Chimera96

OP

Injuneer and GaryDoug have given very qualified solid advice.

As noted the offshore Opti is known for issues due to inferior parts and assembly. Common denominator in chain store brand parts. rockauto.com has a wider range of replacement parts in terms of "economy", Daily Driver and Professional. You would do better getting the later from wherever you get parts

Since Autozone will warranty your Opti and you are selling the car just swap it out for another. Seems like a 50/50 crap shoot on cheap offshore Optis but ideally it gets you to a point the car is sellable..I would also resolve whatever belt or accessory is squeaking

You have a code which points directly at the Opti. You are fortunate in that there is a code. OPTI and ICM can fail and not set codes

97rebuiltZ28

@Injuneer the code was cleared, but when it died it would come back. In my above post I didn’t answer you very clearly. Thank you all for giving your input here. I’ll update later if I get around to changing it out.

97rebuiltZ28

Update: I replaced the opti and it now runs great again! Also I saw I said it was an autozone opti, it was actually O’reilly’s. Another thing I see above I didn’t mention my P0336 which I have know idea why. (I may have cleared it at the time of posting this original thread?) anyway I have had a P0336 since the original time of rebuild and it was already stored in the computer when I first started the car 6 months ago. I replaced the crank position censor too and it still has a P0336. I read somewhere that cheaper Optis sometimes cause the code to stay on.

Injuneer

The crank position sensor (CKP) has nothing to do with running the engine. It was only added to the LT1 in 1996 to meet the OBD-2 requirement for misfire detection. The PCM is looking for TINY variations in crank rotational velocity, and comparing them to the known variations caused by the firing of each cylinder.

The PCM compares CKP pulses to Opti pulses, and a fault with either can cause the P0336 code.

Has the code returned since the new Opti was installed?

97rebuiltZ28

It has returned and even after I clear it comes back. Again I did replace the ckp. But the code was also prestored in the computer when I bought the car unrunning 2k miles ago.