Camaro_gal

hi, I recently just bought a 1994 camaro z28 lt1 5.7 L. At first starting it up took a minute but we assumed that was just bc the car had mostly been setting. while it was cold though the car ran fine never suspected any problems but then On the drive back home once the car had warmed up it started acting up, all symptoms seemed to all be related to the optispark. Loss of power, misfiring, backfiring, stalling and completely dying out. Luckily right when i bout made it to my driveway it made a noise and died out and hasn't started back yet. I ordered a optispark off of ebay for $50 changed it out and still does not start. it fires but will crank until its like the battery is dead. I have tried to research and try to find all possible problems. I thought of the oil cooler being clogged because of a recent cam swap but that wouldn't keep the car from running? The car hasn't ran hot any since the problem started. i have also read that possible bad IGM, crank, knock or cam sensor but i have read a lot of reviews about people buying cheaper optispark distributors especially off of ebay and them being dead right outta the box and most definitely junk! Any input or advice would be greatly appreciated. Thanks

C409

..... Try troubleshooting it ! ... any codes ? ... How long was it sitting ? ... clogged oil cooler ? Geez ! ..... Look at the basic stuff like fire , air , and fuel ... I would start with fuel ... what's in the tank ? .....

Ian67

When you have been trying to start it, does it smell of fuel and do the cooling fans come on automatically even though the engine is cold? If you have these symptoms it could be the engine ecm.
I fitted a new optispark to my '92 Corvette thinking that was the problem. I ended up replacing the stock ecu for a Microsquirt V3 and now it's running again.

pacoW

start with the basics, Spark? Fuel pressure? Fresh gas?

FASTAZU

$50 opti

bob arrowsmith

Please try not to be to frugal when buying opti, you get what you pay for....

1984Z51auto

So, are you getting a Check Engine light? Any codes stored?

95BLKVette

Don’t throw out the old Opti!

Read the codes and post them....that is a must!

Could be ignition module mounted to psssenger side front head that connects to coil and ECM; it fires the coil....basically a power diode.

Good luck.

BrandanC4

If you have spark, then ignore the opti for now. Spray a little gas into the air intake. If it turns over then dies. It’s a fuel delivery issue. Start there. Don’t use starting fluid. Just plain gas

BrandanC4

The opti is like a light bulb. Once it’s gone it’s gone. If your problem is intermittent like mine. Then ignore the opti.

MatthewMiller

When the car began running badly, did the tach still work correctly without jumping around or going to zero? If so, then it's not the opti module. If it runs okay cold (open loop) but then starts running badly once warmed up (close loop), then my first guess would be an O2 sensor. Long story short, that happened on my car with the 94/95 PCM installed and it didn't throw a code until I put the 96 PCM back in. If you aren't getting any trouble codes or a CEL, then you could diagnose this by datalogging the O2 sensors while running warmed up (air/fuel readings). If one side is flatlined then you have a bad sensor.

The opti can have a failure mode of running well cold, if the module is failing once it gets got (again, what is the tach doing?). I would not trust a $50 replacement part - there are known issues with a lot of those things. Ditto the coil.

Purple92

What you describe could also be the coil driver - sometimes when they get hot - they get "unhappy" !!!

As other posters have stated - You need to check for spark - both at a couple of spark plugs, and at the coil output.

Remember - the opti provides the PCM with both a high res output and a low res output. If one is present but one is missing - the computer throws a code - if both are missing - the PCM doesn't think the engine is turning - so no codes...

BrandanC4

Pro-tip...autozone will test your ignition control module for free. Just remember to clean the heat sink with runbing alcohol and put a coat of CPU silicone grease between the ICM and the heat sink.

MatthewMiller

some have the tester and some don't. It used to be that every parts store had them. Another tip regarding testing: have them run the test a few times to make sure the coil gets good and toasty. If you have a heat-related failure mode, it may pass the first time through since it isn't as hot (it gets pretty hot pretty fast during the test cycle).

FASTAZU

And the OP has not returned

Camaro_gal

Camaro_gal

The guy I bought the car from invested some time and money in it. He bought a block out of New York ended up coming out of a 94 capris. Ordered heads from eBay but bare units. Heads are ported. He built the the engine took to garage swapped em out cam swap whole new cam kit. New oil pump, new timing chain, new plugs, wires. Still has break in oil I’m it but am gonna drain it. Did notice some little metal shavings in the oil that’s why I wondered that oil cooler could be clogged. But that wouldn’t keep it from running right? The car had approximately 5 miles put on it since everything being replaced until I bought it drove around 200 miles and has been parked since. Little over 2 weeks ago. Car made a noise and died and hasn’t ran since, I’ve tried everything I could think of. Swapped the PCM out I think it did sound a little different but still not starting. To me the car sounds like it’s outta time.. but is that a possibility? Do notice the wiring looks bad on places and am gonna look into getting that changed out. Got a spark tester all plugs are firing. Could timing chain be off? Out of time? There’s only one way of putting the opti in to bolt back up.

**NO CHECK ENGINE LIGHT**
**CODE PO42**

95BLKVette

One other thing.....I’ve been through 4 opti units over the years so it becomes second nature....the opti also controls your fuel injectors which no one has mentioned. I bet your injectors are not firing! You need to get a Noid light and test any injector plug. Unplug one injector and plug the noid light in the connector and see if it lights when you try to start the engine ...no light equals opti has to go!

BrandanC4

So I found this guy on youtube and he's my most favorite person right now.... The first video is super long BUT will show you how to run diagnostics on all the parts you need to check. It's worth the time to watch and might save you some big $$...Part 2 has some additional diagnostics and shows the actual fix, and the last video he fixes the same issue but alot faster and he even found a shortcut thru the fuse box..

This guy is a freaking genius.


This guy really knows what he's doing;

Video 1 Diagnosis (very thorough)

Part 2
Video 2