edit: See my last post. The problem which broke two optis within 500 miles of driving was the pin in the cam was too long.:edit

After it gets warmed up my 96 SS starts sputtering and backfiring and then cuts out and won't start again until it cools off. It runs fine until it gets hot. I have a wideband O2 in it and it starts going LEAN when it starts sputtering. I also have a fuel pressure gauge and the fuel pressure is fine. I tried a different MAF and that's not it. According to the code it threw and the diagnostics, it's the opti, or the computer. I see no way it's the opti. My computer communicates fine with LT1 edit and the scanner. I've watched it on the scanner and there doesn't seem to be any link with when it goes to closed loop.
I haven't had time to really rule out the computer because I haven't tested it with the new one yet. I only ran it with the old one until it cut out, then put the new one in, and it wouldn't start just like before.

Ideas?

 

The ICM can cause that.

 

What code(s) did you get for the Opti? Heat soak could be shutting down the optical sensor module. The misfires would put raw air into the exhaust, driving your wide-band toward "lean". Heat soak in the ICM could be doing the same thing, as mentioned in the post above. If you have a code for the Opti......

 

I don't remember the codes right now; I looked them up in Mitchells and went through the diagnostics and it says it's a bad computer or bad opti. I didn't know that missing would or could actually cause a lean condition at the O2's, but that's good to know. I don't have a crank sensor any more because of my double roller timing chain, which is a shame because with that sensor of course you can watch misses by cylinder on a scanner.
The darned opti I replaced (again) about 1000 miles ago; but if the new computer doesn't work I guess I'll be replacing it yet again.
Do you know why a new (remanufactured) opti might suffer this problem from heat when the old one didn't? The black sensor on the reman ones it looks like they actually cut the plastic casing, replaced the electronics in there, then welded the plastic back over it.

Thank you gentlemen.

 

Hello,

Yes it could be the opti... but be sure to check the wiring harness
that plugs into the opti. This harness is known to cause problems.
See if you can use another harness (a known good one) to prove
or disprove a harness issue. Also besure to check electrical
conections from the opti back to the ecm. Water/moisture plays
havoc with car wiring so besure all connections are corrosion
free and claen (use an electrical cleaner, most auto parts stores
carry this).

Hope this helps...

 

Something else to keep in mind when replacing
electrical components on any Chevy... Buy the
original Delphi Part. The cost will only hurt your
wallet once instead of multiple times with the
China made or reman one.

Some day in the future after many more years
of trial and error China may be able to manufacture
a quality part as good as the Delphi but until
then buy the Delphi.

Best of luck on your repairs...

 

Thanks. I checked the wiring harness first thing. I haven't checked it all the way back to the computer. The diagnostics said to check it. I don't see how getting hot would cause a connection in the harness to open, but then it has to be something and just about everything seems as unlikely to me as anything else. Maybe I'll try the harness again.
New bad news: I got a used computer to either fix it or rule it out but it needs the new tune in it or it won't run. I tried to upload the tune and the OBDII Programmer software won't let me because it says I only have one license. Perfect right. The list of hurdles continues. I emailed Carputing I think it was and I'm waiting on a reply.

 

Heat soak may be causing the optical cam position sensor in the Opti to fail when hot. If you have the codes for the high and/or low resolution pulse pattern loss, it would be pointing in that direction.

 

this same thing happened to me with a brand new out of the box opti from summit racing. It would die within fifteen minutes of the car running once it got warm. Id let it cool off for a few hours and it would start up and run until it died. When it would die the rpms would dance around a little bit. Most of the time it would die at idle at first and then it would die even at fifteen hundred rpm. Usually thats the symptoms of a bad opti. I thought it was my computer but rarely do these computers go bad. Also im pretty sure that the opti had got some moisture in there because it started about three days after i had driven it through rain something you should never do with these cars as far as im concerned. But like everyone else has already mentioned you should make sure you know exactly what your computer is saying before going to any conclusions even though sometimes its a bitch to read those computers with the different plugs and different years of scanners and sometimes thier locked from a previous owner. Good luck man i was just wanting to let you know the exact symptoms that i had when my opti went bad so you could relate.

 

I'm voting opti because it sounds like the heat soak issue I just spent 2 weeks troubleshooting. As much as I hate to say it I bought one of the 75 dollar opti's on Ebay because funds are low...but it works perfectly and the car runs great.

 

I also say a bad opti!

 

Slick-Z. Thanks. I've never heard of an opti dying this way until I had this problem. Sounds like that's it; your symptoms sound identical to mine. And of course when Injuneer says something it's probably right.
One thing is, I'd just replaced the opti about 300 miles before this problem started, so I'd mostly ruled it out. It's a reman from Advance. They replace the bearing and it looks like they cut open the sensor housing and replace something and solder the plastic back over it. It doesn't look cheaply done; everything looks clean. But the advantage of the Advance purchase is it's a lifetime guaranteed POS. So I won't have to buy another one. I'll just have to put in the 8 hours of work to replace it; after already having paid for two tows, a used computer, and 80 hours of scratching my head and pissing with various things and walking an hour on the side of a highway up to the last place it broke down to limp it home, and the stress and frustration of the lastest problem etc.

 

Yep, bad opti. When I took it off I could hear something rattling in it. Both the heads of the Phillips head bolts that hold the bearing in place had broken off. But that wasn't why the car was dying when it got hot of course.
The first time it started missing I was going over an extended length of very rough road. I pulled into a parking lot and it sorted itself out and drove fine later. When I had to get it towed it was raining very hard out, and it was never right after that. My air filter is 8 inches off the ground and I had the plastic covering off the bottom of the car cause I'm always working it. I figured if some water had gotten in there and was vaporizing when it got hot to blind the sensor, that the vacuum should pull it out.
So the problem is related to it getting wet. I suppose some water got inside the casing of the sensor if that's possible and circuits expand and contract with temperature.
Well, damn the optispark.

 

It broke again, just the same way. It held together for about 100 miles this time. The freaking pin in the cam was too long, pushing on the back of the bearing assembly and breaking the bearing assembly retaining plate. I thought it had broken last time because the bolts in the reman opti were junk. But it was the pin. So I ground the pin down and put it back on.
What was happening was the little disc inside with the 360 slits was rubbing on the sensor since the shaft was off and free to wobble. So it got the sensor hot until it no longer worked.

 

Bingo! Good to know! When I do a rebuild, I am considering getting rid of the Opti if possible. Too many thing to worry about with it. They don't deserve THAT bad of a reputation, but it's enough that for me it's worth changing out.