Corvette C4 Forum 1984 through 1996

optispark distributor question

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  #1  
Old 04-11-2007, 01:07 AM
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Default optispark distributor question

Is it possible to get an optispark distributor installed so far out of time that you loose all spark from the coil?

 
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Old 04-11-2007, 01:15 AM
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Default RE: optispark distributor question

If you have no spark, then distributor timing does not affect that. If it is out of time then the spark will still be there just not firing in time with compression strokes on the engine. You might have internal probs in the Opti, such as a pickup. I would look elsewhere.
 
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Old 04-11-2007, 01:50 AM
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Default RE: optispark distributor question

Thanks for the reply LB. I thought that would be the answer, but I'm a rookie at this stuff. Actually, I may have purchased a faulty distributor. It just doesn't seem likely to me. The original opti was working. I bought a MSD, installed it and when I tried to start it, "no spark". It's also logging a failed start code 41 which would (I think) agree with the rest of your reply. I'm not sure, but I think the sensor in the distrib originates the signal going to the coil so it fires?
 
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Old 04-11-2007, 02:14 AM
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Default RE: optispark distributor question

A dead giveaway would be watching your tach while cranking. If you have no cranking rpm, then either the pickup is bad, not hooked up correctly, or no power to the distributor. If you can check injector pulse with a "noid" light, that will also tell you there might be dist. problems.
 
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Old 04-11-2007, 03:03 AM
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Default RE: optispark distributor question

I don't have a noid light set, but no rpms are indicated during cranking. See, I told you I'm a rookie, too bad you don't live next door. <smile> I'd keep you up nights with tons of questions.
I think I checked the power at the connector where the distributor connects to the wiring harness alongside
the fuel rails. I'll check it there again to be sure. I hate to penetrate the wires on the distributor itself in case it is faulty. I'm leaning more in that direction. (you're a good man LB)
 
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Old 04-11-2007, 08:47 PM
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Default RE: optispark distributor question

You cant mess with any timing on the opti.
 
  #7  
Old 04-13-2007, 12:40 AM
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Default RE: optispark distributor question

Yes, I understand what you are saying about the timing on an opti. BUT, I have replaced the factory opti with a MSD distributor and while I have not adjusted the factory setting, it has the ability to advance or retard 7 degrees. That aside, I convinced MSD the distributor was bad. They replaced it with another one and I'm still getting the 41 error code when I try to start the engine. (cranks but doesn't run) No spark from the coil.
 
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Old 04-13-2007, 09:39 AM
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Default RE: optispark distributor question

Ok, 1st lets look at why. Was your car running before you replaced the dist? I'll have to check my wiring diagrams and get back to you. Have you been able to check and make sure you have a voltage supply to the distributor? I uploaded a wiring schematic. The yellow wire on pin C should have 5v with Key On, Engine Off. Pin D grounds through the distributor. Pins A & B are going to be putting out a digital signal, one high resolution, one low resolution. You might not know what that means, but with the distributor hooked up and probing those wires while cranking, you should get some sort of DC voltage out of them. Also, check your connection on the wiring harness from the distributor to the wire loom. It is up about a foot and a half from the distributor plug in. I had one that the pin had backed out of the harness connector just enough to make slight contact and the car would start and run, but have intermittant dieing problems. The distributor harness is about a foot long and has a connector at the distributor and one upstream a bit. Also, this may seem silly, but verify the rotor is turning. We have a saying in our business. KISS, Keep It Simple Stupid.

[IMG]local://upfiles/1427/B67D887248684658B4AD08C623CA94B4.gif[/IMG]
 
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Old 04-13-2007, 04:03 PM
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Default RE: optispark distributor question

Yes, the engine would start and run with factory opti prior to installing the MSD distributor. After it heated up it would miss,sputter,etc. and then die without setting any DTC's. After cooling down for 30 mins. or so, it would restart and run again until heating up.
I convinced MSD the first distrib. was faulty. They replaced itwith a new one. Now after installing the second MSDit's doing the same as the first one (which was probably not bad).
With the keyON and engine OFF I read 12v.at pin "C" Well above the 5v it should be. Not sure what, if anything, this much could mean.??
I have continuity between pin "D" and the block. While cranking I read 1.5v. at pin
"A",and 2.36v. at pin "B".
I may be getting ahead of you, if so correct me and keep going. I'm not reading any A/C voltage at terminal "B" on the coil module while cranking the engine. It seems all this is pointing at the ECM?
 
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Old 04-13-2007, 06:28 PM
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Default RE: optispark distributor question

If you are getting voltages out of out of A and B, the problem is not in the optispark. Should not be a/c voltage at coil, dc voltage. You can test with a test light with the lead hooked to B+. It will flash if it is getting a signal. Have you checked your coil fuse to see if you have power to the coil? Also check pin B @ coil to see if the power makes it to coil (12v). On the front of the passenger side cylinder head is an ignition coil driver that the ECM uses to fire your ignition coil based on your high and low resolution signals. That might be the place to look next.
 


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