Well, I have changed the opti, double checked the wiring and still no spark. Is there any way to test the PCM?

 

Wow, something is weird here.. Obviously your PCM is working and turning on and everything- running your gauges, and fuel pump and what not... I'm not sure if when the pcm's go bad if they lose all functionality or just a driver or 2. But from the ones i've seen if the pcm is bad nothing works as far as- no fuel pump, no gauges working, no injector pulsing, and no DLC signal...

 

The PCM does not control turning on of gauges or the fuel pump. When you turn the key to on power is provided to those components, that is all they need to turn on. Bad PCM will cause exactly this condition (cranking but not starting).

However generally when the PCM is bad the injectors will not open. So if you are getting fuel I don't really see how that could be cause (unless it is some kind of weird selective failure).

 

The PCM does have to see a signal from the IPC in order to start.- So thats what i meant. As well as the pcm triggers the fuel pump to prime on Key on. ( mine does anyways but its OBDI) My Fuel pump wont prime unless the IPC is plugged in, and the car wont start unless the IPC is plugged in also...

I would agree about the PCM causing the cranking but no starting. and also agree it would be odd for a selective failure.

Im searching for more tests..

 

http://www.alldatapro.com/alldata/PR...1970/130971971

http://www.alldatapro.com/alldata/PR...71970/58923689

http://www.alldatapro.com/alldata/PR...71970/58923690

http://www.alldatapro.com/alldata/PR...71970/58923687

Diagnostic Aids

An ignition coil wire that is open or shorted to ground can cause a no start condition.

Test Description

Number(s) below refer to step number(s) on the diagnostic table.

Important: The battery should be fully charged prior to any tests.

2. Checks for proper output from the distributor ignition system. The spark tester requires a minimum of 25,000 volts to tire. This check can be used in case of an ignition miss, because the system may provide enough voltage to run the engine but not enough to fire a spark plug under heavy load.

4. This test will separate the distributor cap, rotor and ignition wires from the ignition coil to help identify a secondary ignition system problem. It is necessary to unscrew the top terminal on the ST-125 spark tester for a proper fit in the distributor end of the coil wire.
5. This will determine if the proper available voltage exists in the primary ignition circuit.

7. This check will begin to determine if the PCM is providing a signal to the ignition coil module or not. If the PCM is not providing a signal to the ignition coil module, the problem exists between the distributor and PCM.

12. If the PCM is detecting low resolution signal pulses and no IC signal was available at the ignition coil module, a problem exists with the PCM or the circuit to the ignition coil module.
13. If the PCM does not detect low resolution signal pulses. the distributor or distributor to PCM circuitry is most likely the problem. The remaining tests will determine if the proper signals are being sent and received from both the distributor and PCM.

22. A grounded coil circuit will cause the ignition fuse to open, and a no-start condition will occur

 

Heading into garage with troubleshooting guide, see if I can come-up with anything different this time.

 

?????????????

 

Wow. You guys have been doing alot of work trying to get this thing going. Maybe I missed it some were, but did you try to run a new heavy duty ground from the ICM bracket to the frame? If you would give that a quick shot and see if it gets you some spark. I know this seems very simple and out in left field but it has a purpose.

 

You know, that is actually a valid point. I do remember when we were building a TPI car a while back and we got everything together and it wouldnt run, come to find out we had left a ground wire off the back of the passenger side head.. We connected that and she fired right up...

 

Thats kinda what I was thinking. I figure it might not hurt. That stupid braided bonding strap is garbage anyway. If the ground is not closing out in the ICM then you get no pulse out. Or you could also have weak or inconsistent spark.

 

yeah, if you have some spare stereo amp wiring or something laying around- that usually works pretty good...

 

Not the skinny stuff. Like indiroc said it needs to be like the monster cable stout stuff. The thin stuff will melt and burn you. Ask me how I know. LOL.

 

Well, it doesnt have to be like super monster, but an 8 gauge wire should work ok.. Now, the only time the wire should melt is when there are to many amps passing through when there is no fuse. But that shouldnt happen on the ground side..

 

I does infact. It arched and sparked and burt the crap out of my thumb and index finger. It was not my car it was a swap I was helping a friend with. He may have had a bad ground some were else to.

 

Put in new bonding wires and cleaned all the grounds, Still nothing. Anyone have a PCM they want to get rid of?

 

well, we've tried about everything.. I would shoot for a PCM too.. Check on here and ebay..

 

What do you think about the crank position sensor? Is there any way to check it with a voltmeter?

 

Hang on before you throw in the towel give me a chance here. First things first. Unhook the maf before you try to start it. Tell me what is and isnt hooked up.

 

the maf isnt going to affect spark man, but it will affect a/f ratio, however, if there is no maf signal then the computer reverts to the map sensor and the volumetric efficientcy table.

As far as testing the crank sensor, get a good namebrand dvom, one that has a digital scale that moves across the bottom (fluke 73 and others, bluepoint also), back probe the sensor, have someone turn over the engine andwatch the scale, it should go right and left as the wheel turns.

I do happen to have a PCM out of a 96impala if you might be interested in it..

 

How much do you want for the PCM?