Re: First break down ever
 

No it forces it to stay in open loop when an O2 is disconnected.

Re: First break down ever
 

Do a simple ohm check on the coil to test it. Maybe a weak coil that is breaking down at temperature is causing the problem.
http://shbox.com/1/coil_testing.jpg

Re: First break down ever
 

Just got finished throwing a new stock coil on it. Same thing. Going to disconnect the O2 sensor next and see if it keeps running with one unplugged.

Re: First break down ever
 

Unplugged O2 sensor and it stayed in open loop and did the same thing. Let it cool for 3 hrs and restarted and gotthe same result. So this means i have a part that is breaking down when hot? The ICM and coil are both brand new, replaced after this problem started. The ICM was free warranty replacement and the coil was only 20 for a stocker. Only thing left is the opti, PCM, and ?? MAF? This is driving me batty!

Re: First break down ever
 

I think you got distracted from the issue of it going back into open loop then shutting down. What is causing it to go back into open loop?
I'm still learning too but, this is the way I understand things work.
The opti makes a 5v waveform for the computer, it analyzes that and sends it to the ICM. The ICM amplifies the 5v signal to 70 volt for the coil. The coil is just stepping that signal up again.
It would be great if you could monitor the wave form while the engine is warming up. You could watch and see if the wave degenerates. If it does then it's the opti led.
I also wonder if the fuel pressure is staying strong after a few minutes of running, then dies off

Re: First break down ever
 

The PCM does not pass the 5V square wave through to the ICM. It counts the pulses, to determine the cam position, determines when to fire the plug, and when to fire the injector, then sends a signal to the ICM to fire the coil at the right time, and another ground to the injector, of the correct duration to deliver the desired amount of fuel. The fact that the Opti produces a 5V square wave, and the PCM produces a 5V pulse to signal the ICM is coincidental.

The engine will run without the high resolution pulse, because the PCM can determine where the cam is in it's cycle simply by looking at the variable width of the low resolution pulse from the Opti cam position sensor. You will just lose a bit of timing accuracy.

Re: First break down ever
 

Thanks Injuneer. That was a very informational blurb. Like I said I am still learning.

Re: First break down ever
 

Uhhhhhh.....what? sorry not a pro like you guys. That was like speaking russian to me. Can you dumb it down a bit?

Re: First break down ever
 

What didn't you get?

Re: First break down ever
 

He was explaining the difference in the hi-res signal sent to the computer by the Opti was different than the pulse sent to the ICM. He was correcting the statement that I posted.
We are no closer to figuring out the cause of your engine shutting down tho.

Re: First break down ever
 

Roger thank you Psycho.

BW- So hilarious.

Re: First break down ever
 

Dynaspark Opti en route. I'll keep everyone posted. Gotta get this fixed for my top end work.

Re: First break down ever
 

I just asked a simple question....

Re: First break down ever
 

My apologies then. I figured you were being a smart ass since it was your first post of the thread. My bad

Re: First break down ever
 

I have had an issue with something like this....twice. Once with my lt1 and once with my TBSS. Both of them were due to high resistance in the wiring to the ECM. You don't have any kind of ign box like a msd or crane do you?