1996 Vette Opti-Spark

[582Boat]

Driving down the highway the 1996 Vette just stopped, like you would have turned the key off. Replaced the Opti-spark distributor, and all the good stuff. After completing this the car continues to not start. Apparently there is no firing of the sparkplugs. Where do I go next to fix the problem.

 

[ecss]

If no codes are set.

Make sure the coil fuse is good. It's located in the fuse panel when you open the passenger side door. Fuse #25 Coil fuse 10 amp.

If the fuse is good, disconnect the four pin connector at the Ignition coil module.

Pin A is a Pink/Black wire
Pin B is a White wire
Pin C is a Black/White wire
Pin D is a Dark Green wire

Using a Volt meter set to AC,
Connect meter Black probe to a ground or (Pin C Black/White wire is ground).

Connect Red probe to Pin B (White wire)

Crank the engine. Voltage should vary between 1 to 4 volts.

If the voltage is incorrect, could be a faulty PCM.
If the voltage is correct, faulty Ignition Coil Module, Ignition coil or Tach filter.

 

[shawn tallent]

I also have a 96 & no offense but I don't understand when something happens to these cars everyone starts shouting opti is bad.I would almost bet money your coil or your ignition module is bad.I recently had a problem with mine & everyone said your opti is shoot , thank goodness I didn't listen turned out to be a 50.00 O2 sensor. GOOD LUCK!!!! The best way to check is take a old plug wire hook it to the coil with a plug in it & see if its firing if its not the problem is one of the 2 things I mentioned......

 

[cwb]

Thanks doc for posting the message for me earlier, and thank you ecss and Shawn for your ideas.

Here is a little background....
My 96 is stock with 104,000 Mi. We were traveling down the highway when the car completely lost power, display stayed lit but car would not restart. After cranking it over it woul almost act like it was dieseling for 2 seconds.
Upon getting it to the garage we checked the fuel pressure which was good. Next we found that we only had spark on the drivers side. we replaced the opti spark and tried to start it, but had nothing. Had a friend who loaned us a new ignition module and still nothing. Checked it for spark and found that we have spark from the coil but it doesn't leave the optispark. Today on my lunch we checked the module as Ecss had mentioned above and it varied from 1-3 volts... any ideas? Not sure what the Tach filter is... Also, Shawn how do I check the O2 sensor. Mechanic that is helping me said that it gave a reading around 16,000 that went up with every time we cranked it labled "KS" not sure what this ment. otherwise no codes were thrown. Thanks for your help guys, sorry I am not more help at describing but I am definately no mechanic...

 

[ecss]

Next we found that we only had spark on the drivers side.

Are you saying all plugs on the driverside had good spark?
Cylinders 1,3,5,7 and no spark on 2,4,6,8?

we replaced the opti spark and tried to start it, but had nothing. Had a friend who loaned us a new ignition module and still nothing. Checked it for spark and found that we have spark from the coil but it doesn't leave the optispark.

So when you replaced the ignition coil module now you have spark at the wire that comes out of the coil and goes to the optispark?

mentioned above and it varied from 1-3 volts... any ideas?

That indicates the PCM is probably at least receiving the low resolution signal from the optispark and is pulsing the ignition module which is normal.

the Tach filter is...

The tach filter is used to filter the signal at the primary of the ignition coil and used by the tachometer. If the tach filter is defective, it can short out the signal and cause ignition problems such as no spark to the coil or erratic spark at the coil.

Can your mechanic place an inductive pickup timing light on the coil wire? Then crank the engine. He should see a continuious pulsing of the timing light. If the signal looks good, could be a bad coil wire, or the optispark cap/rotor has a problem.

Here's a link that shows the inside of the optispark.

http://www.charm.net/~mchaney/optisprk/optisprk.htm

 

[compyelc4]

Did you check the terminals on the end of the plug that fits in the top of the opti? If your old opti was internally corroded it will be necessary to replace that harness too. When my opti went south I too replaced the opti without checking the input terminals. Finally wisened up. When I checked the terminal ends they were corroded. They were corroded from copper sulfate that was off-gassed as a result of antifreeze "mixing" with the high voltage arc inside the opti. I replaced the short harness, and pump, now all has been fine for quite a while.

Also, did you take a good look at the weep-hole in the pump to make sure it is not leaking on the opti? If the pump is leaking it will take the new opti out quickly.

One other thing to check. Make sure you are getting vacuum on the plenum side of the vacuum hose running from the opti to the plenum. If no vacuum then you most probably have a pinched vacuum hose behind the opti. It receives metered vacuum from the front of the intake manifold. My hose was crimped into a 90 degree bend at that point removing all vacuum from the opti. It is that vacuum that "dries" out the opti in the event it collects moisture. I learned all of this the hard way.

 

[cwb]

Thanks for all of the suggestions we are hoping to work on it again tomorrow...will let you know how it goes.

 

[jjw94]

96 Opti

I also have a 96 & no offense but I don't understand when something happens to these cars everyone starts shouting opti is bad.I would almost bet money your coil or your ignition module is bad.I recently had a problem with mine & everyone said your opti is shoot , thank goodness I didn't listen turned out to be a 50.00 O2 sensor. GOOD LUCK!!!! The best way to check is take a old plug wire hook it to the coil with a plug in it & see if its firing if its not the problem is one of the 2 things I mentioned......

Have a 94 LT1 that I have had problems starting, especially after the car has been driven for a short time. What types of problems did you have when the car started to act up ? Did the car throw any codes, seeing as the 02 Sensor was bad ? Any smell of gas in the engine area ? I agree with you that everyone is saying OPTI when these types of symptons are being seen. I am not convinced it is my problem, even though the GM dealer is saying it is. Any information would be appreciated. Thanks.