Ok, I am swapping a complete LT1 and harness into a toyota (using the GM column, brakes, everything... except I do not have the key with a pellet resistor) and all is well, except the injectors do not fire except once right at cranking. It will fire over, run for 3 seconds, then stumble to a stop. If I spray carb cleaner into the intake, it will run as long as I want to stand there and wash the oil from the cylinder walls with carb cleaner instead of gas.

I took the PCM to a reputable swap shop to have them disable the VATS in the PCM, and supposedly they did that, but I still have to have the VATS Decoder Module plugged in to get it to crank, and the injectors all test good (12.4-12.6 ohms resistance, no grounds in the harness, all fuses good, and by checking with a test light, they do fire once when first cranked) but the injectors do not keep firing to run the motor.

VATS not properly disabled? The pump runs no problem, the starter is never disabled....all seems well, except the injectors only fire once, then sit idle.

Thoughts?

Ed

 

I think you'll have better luck in out Programming/Diagnostic forum, Ed. I'll move this there for you. Good luck!

 

Thanks for moving this! I didn't know where it would be best put.

Anyway, some more info....

I have not talked to the "guru" that programmed the ECM for me as I am a bit ticked at him, but have been studying the schematics for the last half hour or so, and had an idea.

"Everything" worked except the injectors when the VATS decoder module was plugged in, but when I unplugged it, only the fuel pump would run and I could not get the starter to crank. In looking at the VATS decoder schematics, it appears all it does is if it sees the appropriate resistance from the key, it just grounds some wires. Thinking I was not risking much but a relay, I grounded the Yellow/Black wire identified in the following picture coming from the Starter Enable Relay after disconnecting the VATS Decoder Module and sure enough, it cranked just fine.



Applying this logic to the next picture of the schematics, it would seem if I ground the 5 volt dark blue fuel enable signal wire coming from the ECM, it will trigger the ECM to run the injectors on startup and I am good to go.....



but....

ECM's are somewhat pricey for a bum like me, and I HAVE had a few martini's tonight, so while it seems like the logical solution to me, am I risking "letting the smoke out of my ECM" by doing this, or is this in fact all the VATS Decoder Module would do if it saw the correct resistor in the key (if I had the key and a vats ignition switch - which I don't )

Please help, I think I am close here, but want someone who has messed with this before to give me some idea if I am on track.

Ed

 

The problem with grounding that is that the PCM is looking for a PWM ground (notice the square wave icon by the ground symbol in the module). Other people have bought a "module" that people make to simulate this signal. It is made for people doing transplants and don't have a VATS to connect to. There was someone on another board that got one off of Ebay and it worked for him.

Personally, I am not sure your programmer actually disabled the VATS.

 

I wondered what that little square "heartbeat" symbol meant....

The modules...do they allow the removal of the decoder module in it's entirety?

Ed

 

Pretty sure you will still have to bypass the relay for the starter (no big deal), but the bypass module should eliminate the need for the original VATS module. Like I said, it is for people who don't even have a VATS module.

 

[cowardly lion voice]If I only had a brain..[/cowardly lion voice]





I had a friend pull the bin file from the chip, and it was 100% OEM programming on the chip. The programmer is reworking it one more time. If that doesn't take, I'll toss the vats bypass on there and move on down the road.

Thanks for all your help!

Ed