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Jul 14, 2009 | 02:41 PM

Formula96

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Now what????

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)

Jul 14, 2009 | 03:59 PM

ss.slp.ls1

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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.

Jul 14, 2009 | 04:17 PM

Formula96

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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?

Jul 15, 2009 | 08:00 AM

Formula96

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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...

Jul 15, 2009 | 11:31 AM

ss.slp.ls1

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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.

Jul 15, 2009 | 11:38 AM

Formula96

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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.

Jul 15, 2009 | 11:42 AM

ss.slp.ls1

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Quote:

Originally Posted by 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.

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?

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Jul 15, 2009 | 12:29 PM

ss.slp.ls1

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Quote:

Originally Posted by 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.

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.

Jul 15, 2009 | 12:43 PM

#10

Formula96

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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.

Jul 15, 2009 | 12:45 PM

#11

ss.slp.ls1

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Opti harness is good?

Jul 15, 2009 | 01:05 PM

#12

Formula96

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

Jul 15, 2009 | 01:07 PM

#13

ss.slp.ls1

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Quote:

Originally Posted by Formula96

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

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

Jul 15, 2009 | 01:09 PM

#14

Formula96

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

Jul 15, 2009 | 01:10 PM

#15

myltwon

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maybe a blown pcm fuse or ignition switch?

Jul 15, 2009 | 01:23 PM

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ScrapSilicon

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From: back to Jax :(

Quote:

Originally Posted by Formula96

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

Quote:

Originally Posted by myltwon

maybe a blown pcm fuse or ignition switch?

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

Jul 15, 2009 | 03:19 PM

#17

Formula96

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From: Longview, TX

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?