Formula96

first did shbox opti signal test, (i am a dumbass and did it wrong), i thought the results ment coil, replaced, still no start. Did test right this time, not getting 1 - 4 volts on A/C while cranking w/ DVOM hooked up from B on ICM wires to ground. That meant Opti or wiring or PCM, replaced opti wires, no worky.

Today i replaced the Opti, still no fire, getting the same results on the DVOM test.

I don't know what else to replace other than the ICM (can't find a test for it) Crank sensor (checking it now) and the PCM....

frustrated...... (and hot)

ss.slp.ls1

iTrader: (36)

Did you check the three ground wires on the coil stud? One of them is the engine to chassis ground, follow that and make sure it's grounded too.

Formula96

yeah, all good, right now doing misc wire chasing, does anyone no which wires from the opti to the pcm should show signal volage while cranking?

Formula96

alright, was getting 3 volt high res and 1 volt low res at the PCM from the opti, so i figured it had to be the ECM, put a buddy's ECM in and still same results, i know that some kind of signal is getting to the pcm but maybe its not the right signal???

Today we are going to check for perfect continuety from the opti plug all the way to the ECM, if all that is good i am going to take apart the brand new opti and look for failure...

ss.slp.ls1

iTrader: (36)

AFAIK, the opti sends a signal to the PCM which in turn sends a signal to the ICM which then triggers the coil to fire. If your PCM is getting the right signals (only way to test that properly is with an oscilloscope) and your PCM is not bad, then it could be a faulty ICM not causing your coil to fire.

Formula96

forgot to say i did the noid light test on #1 fuel injector, it is not getting signal to fire either, which puts me back to wiring or opti.

ss.slp.ls1

iTrader: (36)

Hmmm.
Is the car is cranking over?
What brand opti did you use?
Rare chance it could be a VATS issue. Is the security light flashing/on?

Formula96

car will turn over all day, meaning not a VATS issue. It was a NIB Delphi from thepartsladi (EBAY). I sent her an email this morning regarding the issue, havn't heard back yet.

ss.slp.ls1

iTrader: (36)

Well the reason I said rare event of a VATS problem is that the BCM supplies a ground to the starter but it also sends a signal to the PCM to supply a ground to the injectors to cause them to fire. Usually the when there is a VATS problem you have a no start condition. However once, and only once, I was working on a 3rd gen and it was cranking over but the injectors weren't firing. Bypassed VATS with a resistor and it fired right up...

Back on topic...you said that your injectors are not firing. Do you have spark? A easy test would be to have someone spray starter fluid into the TB while you are inside cranking it over. If it starts and runs, then you have other issues than ignition.

Formula96

no spark at plugs or at coil, fuel pressure is good, the #1 fuel injector noid test is also a tell tell sign of bad opti, pcm, or wirering, because it gets its signal of when to fire from the opti as well.

ss.slp.ls1

iTrader: (36)

Opti harness is good?

Formula96

brand new... i am telling you, i am stumped. http://www.lsxtune.com/shop/product_...roducts_id/928

ss.slp.ls1

iTrader: (36)

Did you check all of the fuses? In car and under the hood?

Formula96

no (blushes), i believe i checked all that would apply but i will check every one of those bastards.

myltwon

iTrader: (1)

maybe a blown pcm fuse or ignition switch?

ScrapSilicon

iTrader: (3)

sometimes a fuse will look good visually but will be bad when checked for continuity

Formula96

does anyone know if a bad crank position sensor can have anything to do with a no start situation?

I have read that it will not, but my local part slingers tell me otherwise. As far as i know the comp and tach both get the rpm's from the cam sensor (opti). Any help?

ss.slp.ls1

iTrader: (36)

CPS only serves for misfire detection, it won't affect anything.
Your parts slangers probably don't know a lot about LT1's...

Formula96

that is what i was thinking

myltwon

iTrader: (1)

I had a parts slinger who swore up and down that my car didn't have MAP sensor because it had a MAF until I made him look it up