The problem is that GM states that the engine will continue to run with DTC 36. It only needs the low res pulses to run. The high res pulses "fine tune" the spark timing to reduce spark scatter, reducing emissions and reducing the risk of detonation with the stock aggressive timing/CR.

Its only in the last 2 years or so that I've seen people reporting their engine did not run with DTC 36, and I still don't understand why.

 

We shall see this afternoon. And we will crush your rebel alliance. Or not.

 

Fred, I think you hit on the answer to this in one of your earlier posts to this very thread. I totally agree with you, I think the engine will run ..... in the total absence of a high resolution signal. Without any high resolution signal .... the PCM programming just "defaults down" to running the engine on just the low resolution signal. The "no run" engine condition only manifests itself when the PCM is getting intermittent high resolution signals.

Speedy, "crush away" my friend. If you can "generate" an intermittent high resolution signal loss to the PCM, well, there is an "ole" engineers saying ...... "one test is worth one thousand opinions". Keep me "in the loop" as to what you find.

 

Speedy, it is true that a code 36 will not cause a 'computer commanded' shutdown, but your engine can stop running (shutdown) and only throw a 36 and all be caused by a cheap Opti gone south, just like mine did in this thread:

https://www.camaroz28.com/forums/sho...highlight=opti

 

When i had this code ,the car would run normal for a while then bog badly& show code 36 on my scanmaster.The funny thing was that once it did this the car would run great after that providing you didn,t shut car off!when you drove again that bog would occur again.I even tried a test where i got the car to bog once which gave a code 36&then tried to cross 4 lanes of highway(from standing start)&made it across easily b/c if it would,ve bogged again i wouldn,t be alive today!Btw i went to a Msd opti & have had no problems since.

 

Plan on removing the wire and trying it with the signal totally gone and then intermittently putting it back. But the dam battery was dead so maybe today weather depending.

I will post the results soon as I can.

 

Well I did it. In no way shape or form did a problem with the Hi res signal cause any engine problem what so ever... Other than the code, the SES light and the fans come on. PERIOD.

I also learned something about the harness colors from the OPTI to the first connector.

But let me elaborate on the opti signal and what I did. I cut the purple/white wire about 1/3 the way from the connector at the intake and stripped the wires back with the engine running the entire time. I then fanned the connections together for several seconds all while running.

Continued to let it run while I scanned and cleared the code. Of course the code came right back. Then fanned the 2 wire ends together for some more time and confirmed the code. Cleared it and let it come back again very quickly.

Then I twisted the ends together albeit not very well and came back and cleared the code again. Even with the wires crappily twisted together, the code returned. When I cleared the code, the fans and the SES went off. Then within just a few seconds when the code came back, the SES came on along with the fans.

Now everyone has to admit that my signal was as intermittent as it gets. NOT once did the engine stumble or hesitate.

Sorry but the rebel alliance is crushed. I think that the people that had a 36 had another problem and the opti fixed both problems. Maybe they had a poor scanner, maybe they missed a code. Maybe the fact that a 36 sets the SES but a 16 doesn't threw them off. I don't know about that for sure. But I do know what I just did and it did NOT effect the running of the engine.

As far as the wiring from the opti to the first connector. It was different than the shop manual. The ignition feed wire was yellow instead of Red. And I seem to remember others in the past coming across this same thing.

So in summary I proved what the manual says. There is no question. Anyone want to see proof I can tape it and post the film.

 

Speedy, first off you are to be commended on performing the little experiment you described above ..... it is things like this that truly expand our knowledge of the LT1 motors that we have all grown to love/hate.

Now, by using your own words and description given above .... I will show you where your experiment went awry. I will try and keep this very "short and sweet".

See your sentence highlighted above that goes "Even with the wires crappily twisted together, the code returned." What was REALLY happening here was that the high resolution signal that you assumed was getting through to the PCM when you "fanned" the cut wires ...... was really NEVER making enough contact to actually send the intermittent high resolution signal to the PCM ..... as you yourself proved by saying that even with the wires twisted together ...... the PCM was still not getting the high resolution signal .... see what I'm saying here?

That high resolution signal the PCM is "looking for" is a VERY low voltage waveform, which, even at and idle speed of 1,000RPM is sending at least what, 500 camshaft revolutions per minute times, at least 180 pulses per revolution, (i.e. a high resolution "slot" every two(2) degrees on the wheel), equals a minimum of 90,000 pulses per minute, or 1,500 pulses per second ...... at idle speed!

If the wires actually being, (albeit "crappily"), twisted together still set the DTC 36 code ........ then "fanning" them certainly did not send the PCM an intermittent high resolution signal, right!

Also, I think you just mispoke above when you stated that the DTC code 36 sets the SES light when the DTC code 16 does not .... it's just the other way around on my car, NO SES light was set with the code 36, it was just "hard set" (i.e. "active in real time", and not just stored in history) on the scan tool.

Okay .... I'm off to Tatooine now for another rebel allience meeting! (Opps, could you just forget I said that).

 

The goal was to send intermittent breaks not to have the wiring fixed. I had that before I started.

I fanned the connection for several minutes. I was mimicking a faulty (make and break connection). Did it perfectly. I was not making a repair.

It won't matter what you do to the hi res signal. It never did and never will cut the engine off.

And a 36 does and did set the SES. A 16 does not. You are wrong again.

Admit it.

 

so im actually bringing this thread back and i need help, i just put a new petris optisprk in and just tried to test it the code 36 alone pops up and is not working how it should, new spark plugs n wires, even new alternator cuz the old one died, i checked all of the harnesses for the icm pcm and even to the optispark itself, the only thing is im looking at the coil and wire for ignition, or maybe my pcm died throwing a false code 36 but at 5k to 6k it still breaks up, i have no clue and this car has my flipped inside out. i need advice or help...please let me know i have a 95 camaro. the upgrades are only msd wires coil and msd 6al box ive tried unplugging it and just running the regular harness then the msd one. and still nothing.

 

I too am getting a code 36 with my 87 Vette.. It didn't start throwing the 36 till after I solved the code 34 issue lol.

 

Do you have an LT1 transplant in your 87?