But this doesn't mean anything because the pathway for the reference pulse is still the culprit, eg; Ground circuits fail when Hot.

- Rob

 

under service manual and engine cranks but want start- chart A-2, it say ground diagnostic terminal, does light flash code 12? what are they wanting me to ground

 

Sigh... I didn't realize you weren't familiar with these systems, they want you to jumper A to B on the ALDL connector. A is ground, B is the diagnostic request line. When you ground B to A and turn the key ON, the ECM should flash code 12 three times. If it doesn’t flash 12, that means the ECM isn’t grounding properly, and this will tie directly into your hot no start w/code 33 issue. If you jump A to B and do not get code 12, then the ECM ground path is compromised.

- Rob

 

I didn't understand what they were telling/ I know how to jump a and b to get the codes.

 

The ALDL jumper test only gives useful information if it’s done when the engine is hot and in the no start condition. Doing it cold will always show normal behavior, so it won’t tell us anything about the failure. If you jumper A & B during the hot no start and the ECM doesn’t flash Code 12, that immediately tells us the ECM ground path is dropping out when the engine bay is heat‑soaked. That would explain the entire pattern you’ve been fighting. Since this was an engine swap, the next thing to confirm is whether the engine to body ground strap is installed and making good contact, along with the other grounds. A missing or weak strap can cause the ECM to lose its reference signals when hot. Also, when you checked injector pulse, was that during the hot no‑start or only when cold? If they’re pulsing hot, that rules out the old Multecs as the cause. I hear your frustration, but I'm trying to help you narrow this down so you’re not stuck replacing parts that aren’t the issue...

- Rob

 

It's not a "reference pulse" issue. FUGHEDDABOUDIT. A shot of starting fluid won't restore reference pulses. Not "intermittent" or any other kind of "reference pulse" issue. Your problem is NOT "reference pulses". Blee dat. Disabuse yourself of the whole dead end diversion from the path in search of shiny things.

See my signature for a helpful logical hint. Pay particular attention to the concept of "ALL" the facts. Which in this case, the established FACTS are: (a) your engine won't start if the cold-start injector doesn't help it; (b) it's a SWAP, so the chances of improper connection of SOMETHING are rife; and (c) adding starting fluid – FUEL – fixes the whole thing RIGHT UP.

The SYMPTOM is, won't start hot; the PROBLEM is, ECM isn't giving the right little startup shot of fuel. Simple. So simple even someone as stuuuupid as I can see it. See my signature.

D00d, it's JUST NOT THAT HARD. Put aside the "troubleshooting charts", and the "maybe it's this maybe it's that maybe the aliens have sent down their severest tester to determine the intelligence of this inferior race of cockroaches infesting this unfortunate interstellar cinder we found way out here around this piddly little ordinary star", and use some COMMON SENSE. See my signature.

You STILL have a problem (ahem, an "opportunity for a solution") wherein the ECM isn't aware that you've turned the key off and turned it back on again. Until you figure out why your ECM isn't seeing this simple sign of a "restart", you're gonna be chasing your tail indefinitely. Leave your tail alone and use some FORKING COMMON SENSE instead. See my signature.

 

Pretty sure he claimed he changed the ECM and prom as well, so the ECM is clearly responding to bad inputs, and, it doesn't get any easier than checking the Grounds. As for Occam, he stated not to multiply assumptions beyond necessity. To choose the explanation that accounts for all the facts with the fewest unsupported assumptions. A simpler explanation is that the ECM isn’t receiving the correct inputs to command fuel under that specific condition, which is exactly why he should be looking for reference signals, ignition feeds, and swap related wiring...

- Rob

 

Which is, THE ECM ISN'T SEEING THAT THE KEY HAS BEEN TURNED OFF AND BACK ON AGAIN.

Adding starting fluid doesn't restore "reference pulses". Which means then, that "reference pulses" CANNOT in any manner way shape form or fashion be the "problem". (ahem, "opportunity for a solution") They ARE NOT The Problem in this specific matter.

This is CORRECT. You are absolutely right. Leave out the "reference pulses", and William of Ockham is satisfied.

 

I mean it is right here, doesn't get any more simpler than this. When Multecs fail they do not stop the ECM from pulsing. No reference pulse when Hot points to Hi/LO reference dropping, he already said he replaced the ICM and pickup coil, but it could very well be a loose ICM Ground, or a bad connection at the 4-pin or 2-pin module plugs, or the reference wires are too close to heat. Could also be his Ignition feed voltage sagging during a hot restart, I mean what exactly is he reusing from his older vehicle from the fuse block as the injector wires rely on this wiring. The ECM Grounds could also be rising in resistance when Hot. I believe he already confirmed a working CTS. Engine runs fine whgen cold, not much else it could be especially after swapping ECM's and proms...

- Rob

 

Not that it really matters but he has swapped a 1988 L98 engine into his truck. He sent the original fuel injectors out to be refurbished.

RP Multec fuel injectors weren't used in TPI engines until 1989. No reputable place that services fuel injectors will touch the 1989 to 1992 RP Multech fuel injectors. They tell you to throw them into the trash where they all belong.

This being a engine swap I want nothing to do with the troubleshooting beyond sending him a link to a 1988 factory service manual and a video explaining the How, What, & Why these systems work. This type of troubleshooting is hard enough to do over the Internet not being able to see, hear, and touch things and it being an engine swap makes it even worse.