I know this question probably seems stupid, but I just got a new optispark from the store, hoping to fix an intermitant failure I was having. Long story short I put it on but my car would only backfire and wouldnt start, I figured it was my wires to my spark plugs, were in the wrong order. So I took everything off again and pluged them in. Still only backfires with no catch, any advice on what I have wrong? or did I just get a bad optispark? (This backfire no start only began when I changed the optispark so this deffinantly the optispark I just put on) Nothing is modified execpt a shiftkit. Also the ICM and coil are new.

 

You don't mention which year you have, but 93-94 and 95-97 have different versions of the optispark. 93-94 is driven off a spline drive and 95-97 is a pin drive. 93-94 you have to be very careful to index it's position correctly. 95-97 is tougher to screw up, but it still can be done.

It's very important that for both units that they go on flush with the timing chain cover. They should mount without having to "pull" them on with the bolts. Doing so with the bolts could indicate a mounting problem and you may damage the rotor assembly if there is an interference problem.

It's also possible that you have a bad unit. I would only trust GM(Delco) or Delphi units.

There is a sticky at the top of this forum on troubleshooting the opti with an excellent video from GM on the subject. Here is a direct link to the video, but do read the thread as well.
http://www.youtube.com/watch?v=lFCjaz6zHfc

For proper indexing of the opti from Shoebox's site....

93-94


95-97

 

Sorry I have a 94, So I have the right optispark. I took off the optispark and realigned the teeth, it went right on. I was putting back on the sparkplug wires when I noticed that the wires to 1 and 8 didnt want to click into place, I looked at the wires and noticed that they are missing a small circle of metal on the inside that all the other wires have. I think it might be possible that they broke off when I took the old optispark off. Do you guys think that bad sparkplug wires could be the cause of this new issue?
the piece that is missing is the snap lock plug grip on the two wires:
http://image.circletrack.com/f/engin...plug-wires.jpg

 

If that piece is missing you will likely get no fire from that plug. It shouldn't cause a backfire, but a bad miss.

 

could that be what I am experiencing then. I have smoke shoot out the front of my engine when I turn it. I assumed that was a backfire, but maybe thats what your talking about. Sorry I am a first time mechanic

 

What brand is the new Opti?

Are you absolutely sure the plug wires are on the correct terminals?

Did you loc-tite the new Opti rotor screws before you installed the Opti?

Are you absolutely sure you have the "odd tooth" on the Opti splined shaft aligned correctly? "Went right in" does not guaranty it is correct.

 

Its a GM

yes I just replaced all of them still no start

No I didnt use loc-tite

I am not, the odd tooth on the opti is alot smaller on this opti than on my old one. I am getting 1-4 volts to my coil, I am not sure if that means its one right or not tho.

 

You should elaborate on this. Try to be more specific what you are talking about and give a better description where it is coming from. If it is coming out of the throttle body, and you are sure the opti is aligned correctly, then recheck the firing order on your wires. Also it would be easy enough to replace the old ICM and coil assuming you didn't replace them to troubleshoot the backfiring..

 

Since you're not sure the opti is installed correctly you need to remove it and make sure. The symptoms you describe are typical of an out of time distributor. Take the cap off and check the rotor screws while you have the opti off. You can start the car without the water pump to make sure it will run before you put it all back together. If you still have the old opti you can compare the position of the rotor and the large spline on it and the new one. That may make it easier to be sure you are using the correct spline on the new one.

 

Just to comment on the plug wires, they can easily be the source of a misfire. I had a set that had no visible issues, were fine at idle, but at high load would misfire left and right.

If they are old, then change them out with good brand. I use AC Delco wires, but they can be pricey compared to the AutoZone/Advance brands.

The reason I stick with them is that they go on fairly easily without a lot of fighting to click on to the plugs(they are good quality wires too). Nothing worse than having to fight to get a tight set of wires(boots) onto a plug in the tight confines of the LT1 engine bay in an F-body.

To flat out not start though, does sound like something other than plug wire issues.