C4VetteLS1

I had my ls1swapped c4 vette running fine with the painless wiring harness and the VATS bypass box wired in that came with it.

I used ls1edit on the car for the first time to program for the larger injectors i have in the car (accel 30lbers) and i turned VATS off in the software, raised the idle 200 rpm, changed the rev limiter to 6800. I then flashed the pcm with the new program (first time using ls1edit on my car)

The car will not start now. The injectors harness is not firing ANY of the injectors. But when i first hit the starter the car hiccups for a split second like it goes to start (meaning a tiny bit of fuel must get in) and the car goes back to just cranking. the plugs have spark also, i checked that. But after the single hiccup/stumble the car doesnt try to start whatsoever, just sits and cranks smooth.

It only hiccups after you have the key off for about 2-3+ minutes, not every time you try and start it.

What could turn the injectors off? I ls1edited it back to stock and still doesnt work. I turned the VATS off and on both in the software and it wont start, I unplugged the VATS box and turned it on and off in the software and still nothing. I also checked all the fuseblock fusesg/grounds/connections.

Light84vette

Doesnt the LS1 PCM have a feature that doesnt allow it to start if it thinks it is being stolen? I Really dont know about that, just maybe something to look for?

LS1swap

I am guessing you have already checked this, but you do have 12V to the pink wires that feed the injectors.( the pcm nearly grounds the injector it doesn't supply the power) Maybe you got a bad relay from painless and it is not turning on. it has been known to happen they are only $2 items. With the key in the run pos. You should have 12 volts to all pink wires ( assuming painless stuck to the same GM color codes) will it run on carburetor cleaner or either? ( not that you should run it on either very long). It will at least tell you that you are getting spark and it is a fuel problem. I don't think it is VATs if you turned it off with LS1 edit

C4VetteLS1

I will check that first thing monday morning. thanks.

wm_sorg

This may sound off the wall but change or clean the plugs. There were two guys here that had similar problems and the cars fired when they did the plugs.

C4VetteLS1

Changed the computer with a stock ECM out of a buddies car this morning, car fired right off!!

I dropped my computer off at the chevy dealer to get reflashed this morning.