Oh man once you add in a human may have messed something up things get WAY more complicated. From personal expearance the last thing a mechanic want to see on any job that needs diagnoses is new parts. There are only so many things that will fail in normal use of an engine but add a human in the mix and just about anything can be wrong. Even if the car sat the opti would be really clean if its never run.

Before you do the compression test do a vacuum test and let us know what you reading is while cranking. Extremally low vacuum could indicate a plug cat or a timing chain jump. At cranking you want 3-5 inchs. While I do believe compression could be an issue because of the water it is hard to believe that you do not have 3 or 4 cylinders that would be good enough to make it sound like it was really trying. Engines normally fire really easy on starting fluid. I have used starting fluid on an engine that had about 80 PSI of compression. It tried to start and I ended with a fire ball out of the carb. Low cranking RPMs could cause low vacuum.

If you do not think the motor is turning fast enough add a block and chassis ground. That is just a wire from Neg side of the battery to the motor and a ground from the motor to the fender. If the Motor sounds like it spins faster, or these wires get warm you have a grounding issue. You can, but I do not advise adding a wire from the battery to the starter. Instead do a voltage drop test on the main battery cable. That is when you set you volt meter to DC 12V put the positive lead on the Positive post of the battery and the negative lead hooked to the other end of the main battery cable at the starter. When cranking read the voltage. If it is much over 1 volt then your positive cable is shot.

 

That's a really good point about the block and chassis ground, and drop test at the starter. I meant to do both today, but my heart just wasn't in it until my son got home. It does sound slow to me compared to other startups I've heard on good cars. The guy I bought this from, basically an F-body mechanic with his own shop, said my compression sounded good.

But speaking of which, I have some new information to add.

I wanted to return the noid light set tonight, so we re-tested. #4 did not get a pulse on any test we did. Each time we would get a good one, another random one after that (usually on the same rail) would not pulse immediately after. It would take a key out-key in process, usually with a little bit of a wait, to get another one to pulse. All of these injector plugs got 12v on the supply line. I do smell at least some amount of gas being dumped, or else I smell it out of the Schrader valve, but it's only after a crank attempt.

This is the spark test, happened to be #4 again, because it is easy. Good continuity between tester and a ground. Shirt between tester and A/C lines to make sure it didn't find an easier path. About 25k on the gap. I think the spark is a bit weak and inconsistent, but I absolutely am not an expert here.

 

I am not getting even 1 volt on the return line on the ICM harness. Combine that with good spark at coil and inconsistency with the spark plug spark and injector pulses, I ordered a new Opti today.

I genuinely don’t know what else it could be at this point. I can return it if I find something else is the issue, or get a bad one. I cleaned up the battery ground on the pass fender, saw that a PO put in a new starter recently and the connections are pristine.

Taking the water pump off will also help get the new plug wires on, so this seems like a good mesh.

 

Replaced the Opti after checking the harness gave nominal values. Only difference with it is I got some vapor backfire out of the intake. It still isn’t sparking properly, still not getting 1VAC on terminal B on the ICM harness.

 

check connections at the pcm for any corrosion or damage, also check wiring as best you can for anything out of the ordinary as well.

 

Good continuity on the white wire to PCM, zero ohms. Connections are immaculate.

Still troubleshooting.

 

I guess I'm down to figuring out why the PCM isn't supplying at least 1V, that's the big mystery. Lots of people over the past couple of decades with zero or over voltage, I have yet to see anyone with low consistent voltage.

The roundabout manner that the electrical signals is so confusing. If the ICM isn't receiving the proper voltage, it can still be the ICM's fault?

 

icm is not that costly. I had one go and it was confusing to figure out. it would run for 20 minutes and die, get a ride home and come to tow it home and it would start and make it home. finally just wouldn't run at all. after that I started carrying a spare in the car. at the time I was driving in secluded areas with no cell coverage so was concerned with how I would deal with it if it failed out in the middle of nowhere.

 

I got my oscilloscope today, so perhaps some answers are forthcoming. You are correct, an ICM isn’t that expensive, even for ACD. Which the one on here is, BTW. I think the coil is as well. Who knows how old they are.

 

Waveforms for the low, high, and ICM pulse. Had to take videos because I could not figure out how to output a picture that wasn't after it was over.