when checking these harnesses you can't always just look for continuity. measure for resistance. anything more than about one ohm is too much.

 

Ok well as i suspected it was the ICM. I also used some washers to space the whole bracket off the head. I'm still gonna replace the Opti anyways just cause it has a ton of miles on it and the notorious manifold leak has got some oil on it. I go out of town too much so might as well just replace it to stay on the safe side.

 

Jordon,

I had a similar problem... Check to see that nothing is driving off the ignition circuit to power ANYTHING. the pcm will "overheat" and shuts itself down.

I do not think its the opti on this one. Check the pcm ignition voltages.

I had this problem when i installed my CSI water pump off the ignition source... car would run fine... Shut itself down, quickly changed the pcm and car fired back up, do that test. Could be a faulty pcm or pcm being voltage drained.

 

Check the ignition module(white plastic thing) at the bottom of the steering column where the circuit from the key is transferred from the switch to the ecm and wiring harness.Its is mounted on top of the column. I found one that was fried and it exhibited the same problems you are describing. I could be wrong but I think its your problem. Its a $6 part but mif signal isn't transferred then it won't start or stay running.

Vince

 

spray-
Thats a good idea, thanks.. something to try.

OK, well, as an update.. I yanked the front off the motor (Ysi trim and WP) and put another opti on it. also disconnected the MSD. the combination gave me spark.

BUT NOW the bastard still wont start. it just coughs through the intake a bit.

Anybody know how to make a noid light? I really just need an LED and a resistor I would assume. How much voltage does the PCM pulse?

what a pita. no codes. here is the datamaster file while cranking.

http://www.fastblackcar.com/misc/again4.uni

*rips hair out*

 

I know its sounds stupid and I know youve been around these cars for along time but it from what it sounds liek now is that your off a couple of teeth on the opti. Now that youve got spark and fuel I would check the down and the optiand make sure your not a tooth or two off. I thoght it wasnt possible until I did it in my car.

 

Check what i told you on the PCM. can be a faulty or problems with the pcm.

 

a) Are you getting the proper values at the ICM?
b) Are the injectors ticking?


If a and b, then seriously check the harness(or fuel tank).

The best test is what I wrote earlier in this thread, put the opti signal on a DSO and see what is making its way thru the wires.

 

The signals seem to be correct at the ICM, not sure on the injectors. hence the reason I want to make a test light.

 

You can build one up with a resistor and LED but i just cheat and listen for the injector ticking with a long snapon screwdriver.

If you hear any ticking then assume that is not the problem because it would atleast fire a bit. I know it sounds like harping but when I lost the harness at the opti, injs didn't fire a bit and ICM was testing right. If they are firing and the ign is not, I can hear then without the 'bone conduction stethoscope' with no problem. Those little joker are louder than you think.

The other detail of my testing is hook up a spare opti outside the car. So you don't hear the starter. Just spin the wheel and the inj will sing to you. Nice for under the hood testing of LT1 inj and ign.

 

This is the best thread EVER for opti info!

 

best idea, EVAR!

 

Jordon,
I had a similar no spark situation with my sons 93 Z. Lost the low res signal
and set a dtc 41. Replaced the opti, and still no spark. The 41 cleared and now have a low res signal...no spark. Followed a pinpoint test in shop manual and had all the correct readings, tested harness and connectors for resistance, all good. replaced coil and icm (all ac delco stuff) .. no spark.

I found the small "pos" connector that plugs into the icm (small 4 pin connector labeled a b c d) was all good when testing for voltages, but the openings that actually slide over icm pins were slightly ovaled out of shape. Not sure why..but I reshaped them with my oring pick, (compressed them some) plugged it back in and now I have spark.

Maybe a long reach...but when grasping at straws...get a handfull!!

HTH

Keith
p.s. I think I remember you from the old LT1 edit days when that list first got going!
I was Offshorerunner back then.

When you find out what was wrong please tell us!

 

anymore news on this?

Good luck

 

Jordan,
The Opti is faulty and a PITA to change. It heats up and fails; it cools down and works strong until hot then dies. You'l have to get a new one; the GM's are better than after market. That's my guess.
http://web.camaross.com/forums/newre...e=1&p=3061495#
Confused
Bill