Jcastro2333

I just bought a 93 firebird formula with 86,000 miles on it and it randomly shuts off when I drive it. The first few days I had no issue then now out of a sudden car will randomly shut off after a short time of driving. The times that this has happen to me time varies before I can start the car up again some times I can start it again instantly sometime it takes 20 mins to a hour before I can. I haven't noticed anything wrong with the car driving wise it will drive good then just shut off randomly. Anybody have any idea what could be going on?

Jcastro2333

Sorry forgot the mention I texted the previous owner and he said he did put a brand new ICM.

joelster

Ignition switch on the steering column. Very common for them to fail. I had to replace them on both of my 4th gens.

bowtienut

iTrader: (1)

I've had one opti failure and it acted exactly as you describe.
Failure of the high res portion shuts off the injectors.
Do a search and you'll find instructions on checking for high res pulses, before you pull the opti.

joelster

When you say it it takes 20 minutes to start it up again, is the starter engaging? Or are you turning the key and nothing happens?

Jcastro2333

Starter is ingauging I feel like it might not be getting any spark I've been told most likely it is the optispark starting to go bad it's random though I drove the car all day today with no issue. I bought a new optispark today and plugs and wires. The car has 86,xxx and I'm assuming all that stuff is still original I'm just worried about changing all of that and it still having that random issue.

hrcslam

You need to verify the issue before you throw parts at it. When you are having the issue, check for spark AND fuel injector pulse. If you don't have both is likely the optispark. If you have either one, it's likely not the optispark.

What brand optispark did you get? This is important.

If no spark only, check icm and coil. Maybe cap and rotor.

myltwon

iTrader: (1)

Verify fuel pressure. Should be 40ish psi with the key in the on position, spike to 43-47psi with the vacuum reference pulled off the FPR, and after the car is shut off should take quite a while to bleed down.

Could be the optispark as others have suggested, but unless you're sure that's the issue its one of the most over-blamed parts out there.

warriorcustoms

iTrader: (10)

On My 3rd gen Z28 the ICM would do that & I pulled it out & put new dielectric grease on the thing... Never done it again... The 4th gen is a totally different animal LoL the Security VATS bullshit can Drive Ya Nuts!!! My firebird was doin stuff pretty close to what your explaining... I ended up replacing the key switch because the wires were broke on the thing... After I did that I found this site & the VATS delete how to thats the way to save yourself some Headaches!!! Google or search on here for VATS bypass or VATS delete... its Easier than the key switch lol You can turn it off in the PCM if you have tuning equipment... After that if its not runnin test the Opti harness , ICM & coil

Jcastro2333

Just wanted to let you guys know I replaced the optispark and it resolved my issue.

bufmatmuslepants

iTrader: (3)

Thanks for updating the thread, helps with a lot of people troubleshooting when threads have a resolution and don't just die

ahritchie

iTrader: (1)

OPTISPARK