I've got more variables at play with this one, than 7 guys riding motorcycles in the Globe of Death at a circus.

I got an LS2/T56 package out of a wrecked 07 Cadillac CTS-V, which I've now got in my 73 Mach 1. I was told a Painless 60524 harness would work, though it's meant for an automatic tranny. I later found out Painless doesn't make a harness for any manual tranny's, let alone for an LS2 out of a CTS-V.

After a lot of trials and tribulations, it appeared Painless was able to put a tune onto the E38 ECM I provided them, which would supposedly work with a T56. No TCM is supposed to be required and only a jumper at the PRNDL connector to make it think it's in Park.

Where I'm now at is I almost never get a ground pulse to any injector, so the only way I can start it, is with starting fluid. Every once is a great while though, I'll get one pulse (NOID light flashes), and a hint it wants to start.

The 12V to the injectors is fine, and I switched the cam position sensor wires though they ohmed out as expected before switching, so I had little hope. The 5V supply to that sensor and the crank sensor are fine too.

I'm going to install a new cam position sensor, once I can figure out how to pull the old one out, which won't even come with a decent vice grip tug. I doubt that will do anything though. I've also read in some forums, the engine will start even without the sensor working, just take a little longer to do it. And, I'm not getting any error codes.

Obviously, ECM could be the problem, though the guy at Painless said it is good, and I can't just slap any old stock unit in to try it. I'm more suspicious of a grounding issue, given that every once in a while, I'll get a single pulse. I've attached the two grounds in the Painless harness to the two heads, and run ground straps from both heads and the alternator (which I also replaced), to the body. I even added jumper cables to ground, just to test with.

I'm still waiting for a call back from Painless, to see if there is any chance one of the automatic tranny connectors I've left unhooked, would be used as a ground source for the injector ground pulse circuit.

Does anyone know if there is a specific pin, or pins I could check on the ECM, which should be grounded for the fuel injection circuit? I have E38 pinout diagrams for the various individual injector signal wires, but I would expect they shouldn't be grounded except when the ECM provides the signal.

Any other suggestions would be welcome too.

 

One more variable, though I think it's inconsequential. The CTS V set-up originally had an E67 ECM which has three connectors, so what little TCM it might require with a T56, seemed to be integrated into the ECM, versus a completely separate unit. Painless' harness is designed for a E38 though, and a separate TCM, which I'm not supposed to need.

 

Wow, you are brave! Just a shot in the dark. I assume the CTS-V LS2 has a 58x reluctor wheel. Is your E38 ECM set up for a 24x wheel?
The reason I ask, is it sounds like the ECM is not seeing the engine rotation and not firing the injectors.

 

"Brave" isn't the first word that comes to my mind, or second, or third, but thanks. I'll double check with Painless, but they specifically asked about the gray or black colored crank position sensor connector, and it's supposed to be programmed for the gray (58 tooth).

I'm not looking for the tune to be the final one, just enough for me to be able to complete the install and drive it to a tuner.

 

I wonder if there is a ground loop issue going on. Some ground connections are dirty (different potentials) and if you have too many hooked into each other, a ground loop can ruin every sensitive signal, such as sensors and injectors.

I'd remove all the grounds to the injectors and replace it with one (known) quality ground. All grounded connections are grounded at all times, not only when the ECM is on.

 

Damn, I haven't heard the term "ground loop" in ages. I used to be a microwave/RF test equipment tech, and they could wreak havoc in all kinds of ways.

I thought the fact that it turns over great, has good spark, and measures virtually no resistance at all ground points meant I had no ground issues, but you might be on to something. Virtual isn't the same a literal though, and that might be enough of a difference.

The guy who owned the car before me moved the battery to the trunk, so I'm relying on a chassis ground from Timbuktu, somewhere in the rear of the car. And all of my engine grounds (two heads & alternator) are attached to different places on the chassis.

And, as I said, it's extremely intermittent, one pulse only, nature, has had me suspecting ground issues for a while. I'll move the battery to the engine bay for a test, and run direct grounds from the heads, chassis and alternator, all in parallel, and see what happens.

Great suggestion, regardless. Thanks.