AtlasXVIII

My 96’ z28 apparently is dead. I was on my way to a car meet and after driving 5 miles the car stall, but it started right up. I continue my way to the event and at a red light I found this sexy WS6 TT revving at me, we do a little 60 pull “I know I was going to get my *** whooped” but I played a Little bit with that guy, after reaching 100mph the car stalled. I tried to star the car again and it was back firing at high RPM, and stalling, the car would idle for few seconds ok, but then die again. I don’t know how you call the car went it idles cold, I think is called “close loop” or something like that but the car was doing that. The car would rev to 1,500 rpm and then drop to 800 rpm, and continue doing that but stall. After few tries it starts right up drove about 1 mile and stall again. Got it towed home. Before that the car stalled about 2times 2 months ago in my garage but would fire up again. I got a new daily so the car was parked for about 1 month. I put new ICM, COIL and crank sensor they did have warranty “Love auto zone” the car is not starting anymore. All fuses are good, Fuel pump primes, no security light, Fuel pressure is 42.5. The car cranks but no start. Don’t have pulse to the injectors or power to coil “no spark” the only thing left is the Opti. 96’ lt1’s came with vented opti but apparently the last owner remove the lines of vacuum. I ordered the lines and fittings- GM p/n 12555323 and GM p/n 14082470. I’ve making some research about opti prices and the ac Delco is about $500, AutoZone have the duralast for about $220 and lifetime warranty but cheap stuff scares me. “You get what you paid for”. I was reading something about low resolution signal and how they affect everything. Is there any way I can test the opti?

GaryDoug

See this procedure, especially the part about the low res (pin B) signal test.

4th Gen LT1 F-body Tech Articles

I do not recommend testing Ohms with the ignition on, so do it only with the ignition off.

Injuneer

Tech problems should not be posted in "Parts For Sale".

Moving to "LT1 Based Engine Tech".

Injuneer

Could also scan it for codes. There are trouble codes for the Opti.

Why did you replace the crank sensor? It's only there to detect misfires, and has nothing to do with running the engine. Did you have a code for it?

Cheap Opti's are a complete crap shoot..... generally have high failure rates. Some people get lucky though.

AtlasXVIII

Can’t scan for codes, it says “Error communicating with Computer” I change the crank sensor because it was under warranty.

Injuneer

Check the cig lighter fuse.

Chimera96

First check the fuse Fred notes

you could very well have a electrical or mechanical failure with your Opti.
But....
It would be very helpful if you scan for codes

a unvented Opti can quickly build up crud inside which will prevent it from operating. You would need to pull it, remove cap & rotor and look inside. If so you can carefully clean it with Q tips & alcohol

AtlasXVIII

Cig fuse is ok, I can charge my phone there and would power up the Scanner. Maybe the last owner cut something? I check already and all cables seem to be ok. I’m waiting till I have space on my garage to pull the opti out, I order a volt meter just waiting to test the opti before removing it.

bw_hunter

I'm nt quite sold on the idea that a vented Opti will build up with crud if the hoses are disconnected that would be significant to keep the thing from operating. I guess it's possible but I think it isn't likely.

If you can't scan for codes you may be able to reset the computer and get it to run. Disconnect the battery or pull the PCM BAT fuse for a short period of time and reconnect it. THen check for spark or injector pulses...

Chimera96

GM changed to a vented Opti because non vented Opti's did get oxidation build up

From personal experience I had Optis die (brand new dealer installed AC Delco Optis) in 500-800 miles due to a non venting system (Mr Goodwrench at some point reversed one of the blue/white check valves on the vent harness during Opti service)

The green slime just poured out of the Opti....3 of them. All of these were done back in 97 when car was still under warranty.

Fortunately I saw the problem at a cruise night when I was parked next to another SS (Impala) and saw the orientation of his check valve was opposite mine. No problem since I put it back on correctly. I did inform the Service Mgr and mechanic of my discovery and it was a face palm moment for them. The dealership did sponsor our car club and was very willing to work on modded cars and even install head/cam on them.

Since the OP noted he didn't have a vent harness on I brought up the "possibility" his Opti problems may be due to oxidation contamination.His issue could certainly be a physical failure within the Opti or somewhere else in the ignition system. It will be clear if there is Oxidation inside when OP removes C&R

bw_hunter

Please understand that I don't discount your experience, I just don't think that is a typical failure with an opti. Firstly, the oxidation products of brass are typically black, not green. It's generally a powder, not a semi liquid. Yes, there are copper pieces in the opti but the oxidation products of copper are either black or red. The green you described came from something else to my way of thinking.

I've take apart several optis including the one from my 94 that I replaced when I went to the vented setup. The unvented opti, which worked fine, had a thin reddish residue over everything. It wasn't enough to interfere with anything and that opti was about 40,000 miles old.

Anyway, asides like this don't help the OP. he needs to test the opti using the methods outlined and then decide if replacement is indicated. Which is probably the case but with several hundred dollars on the line it's best to be sure...

GaryDoug

Copper oxide is black, but the natural patina layer that copper produces over time is brown, slowly turning green-blue after a few years. The Statue of Liberty is a classic example.

bw_hunter

That blue green color is really an effect from acids in the air...not an over time change in the oxides. Copper sulfate, copper nitrate, etc. are that sort of color. Oxides, like those formed inside a chamber full of ozone are black or red....and not slimy

GaryDoug

Patina | Definition of Patina by Merriam-Webster

bw_hunter

It appears that Mirriam Webster and I agree that the green patina is a product of acid in the air.

Ozone in the opti is different.....color and chemistry.