LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

how to test for spark thru an opti WITHOUT having it installed!

Old Jan 16, 2014 | 07:15 PM
  #16  
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Re: how to test for spark thru an opti WITHOUT having it installed!

And you are using the correct method to short the pins and read the flashes? Do you get the 12 code?
Old Jan 17, 2014 | 01:41 AM
  #17  
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Re: how to test for spark thru an opti WITHOUT having it installed!

I have a code scanner for the 1993. But yup i get the code 12 3 times and then get 28 3 times and 66 e times then right back to12 3 times.

Ive got it running now though. I had 4 optis and 3 of them had something wrong with them. Have 2 92-94 spline styles and 1 95-97 style that was untested.

1st unvented opti has 260k on it cap was destroyed but still ran rotor was junk too.

2nd unvented opti the disk that spins and tells what cyl to fire ripped in half (bearing failure)

3rd and final opti (vented) was untested.

So i tested the vented opti and all worked how it shouldve but the mileage on it is unknown so i came up with a plan. ill gut all 3 and rebuild one FULLY Working hybrid opti.

So the end result was i had the 260k mile opti shell with the 2nd non vented optis optical sensor and the vented optis cap and rotor button. So hoping its all going to work i put it together ran my vac line for the opti hit the key and it fired right up, revs alot faster then with the old opti too,

So now i have a spline driven VENTED optispark. Best of both worlds to me.

Check the youtube name in the video posted above for the most recent video.
Old Jan 17, 2014 | 01:45 AM
  #18  
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Re: how to test for spark thru an opti WITHOUT having it installed!

Oh and fred thanks for all of the help with everything, not trying to nut swing. Just really appreciate the help and thanks to everyone who helped out aswell. You guys kept my eye on the prize
Old Jan 17, 2014 | 09:41 AM
  #19  
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Re: how to test for spark thru an opti WITHOUT having it installed!

Originally Posted by SuperSportSS
Yup checked for codes and nothing. So i think it has a bad optical sensor and its not throwing a code, every bad optispark ive had always never throws a code. I dont get it. You guys that get codes are lucky.
What went wrong with them? You won't get a code for a problem with the high voltage section (cap/rotor). Only problems with the optical cam position sensor will set codes.
Old Jan 17, 2014 | 06:54 PM
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Re: how to test for spark thru an opti WITHOUT having it installed!

Ive had to change 6 in my time of having lt1 cars. One went completely out no codes no nothing and it was the optical sensor 4 got water in them and rusted so bad they wouldnt run right and the last was this one. Never got a code
Old Jan 17, 2014 | 08:01 PM
  #21  
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Re: how to test for spark thru an opti WITHOUT having it installed!

First time in the 18 years of working on these cars I've heard anyone have that problem. Might want to try replacing the ECM.
Old Jan 17, 2014 | 09:40 PM
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Re: how to test for spark thru an opti WITHOUT having it installed!

This all happened on 4 different cars. And theyre ecms were fine.
Old Jan 18, 2014 | 03:51 AM
  #23  
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Re: how to test for spark thru an opti WITHOUT having it installed!

Just wanted to update and share, the optispark in the video in post #1 was put on a 1995 z28 today and it ran the car perfectly. A friend was changing his water pump and figured we would spend the extra 15 min and test this opti. It fired his car right up and never gave an issue in the 5 min we had it running before having to shut his car down so it wouldnt do any damage.

So the test does work for testing optisparks so far. Ive tested 3 so far this way and theyve worked well so far tested 2 spline driven and 1 dowel vented style.
Old Jan 18, 2014 | 08:02 AM
  #24  
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Re: how to test for spark thru an opti WITHOUT having it installed!

Just an FYI in case you don't know about it, but the vented optis also had a bearing vs. the bushing on the earlier style. I think that is one of the reasons they go on for a long while and can easily be rebuilt with just a cleaning and a cap/rotor change. Honestly, I don't think there are near as many problems with the later versions.
Old Mar 29, 2014 | 10:15 AM
  #25  
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Re: how to test for spark thru an opti WITHOUT having it installed!

Ive had a few optis tested this way now and it has worked every time for me so far with the 15 ive tested this way so if anyone needs to test an opti on the fly just make sure you dont spin it by hand it will shock the hell out of you
Old Aug 27, 2019 | 05:50 PM
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Re: how to test for spark thru an opti WITHOUT having it installed!

i had read on a previous thread tha the IAT sensor has an influence on the timing, by the list you left us, im going to assume that it would be a myth?
Old Aug 28, 2019 | 06:44 AM
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Re: how to test for spark thru an opti WITHOUT having it installed!

Originally Posted by joesz2814
i had read on a previous thread tha the IAT sensor has an influence on the timing, by the list you left us, im going to assume that it would be a myth?
I wonder if there is some validity to that. Ive noticed the factory IAT sensor installed in the 1LE air intake elbow is physically shorter the factory IAT installed in the stock air silenced air intake elbow.
They have to have different part numbers because of the obvious physical size so I was wonder what effect the different IAT does if any.
Old Aug 28, 2019 | 08:24 AM
  #28  
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Re: how to test for spark thru an opti WITHOUT having it installed!

Originally Posted by joesz2814
i had read on a previous thread tha the IAT sensor has an influence on the timing, by the list you left us, im going to assume that it would be a myth?
You might want to start a new thread for this topic, since it is off-topic, having nothing to do with pre-testing an Opti. Plus it's unclear whom you are addressing the question to. If it is the “thread stater” he was banned from this site a long time ago and cannot respond.
Old Jun 4, 2025 | 08:17 AM
  #29  
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Re: how to test for spark thru an opti WITHOUT having it installed!

I've got a 95 Z that I've been troubleshooting for WEEKS. No spark, etc. The customer brought me a new Optispark and I am going to use your method to test the new one. You are a genius! Your method will save me HOURS of disassembly/reassembly WITHOUT knowing if this is really the issue. THANK YOU! YouTube - @lonzgaage
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