starts then shuts off

[scotzilla]

I swapped a 95 lt-1 from a vette into a 71 buick skylark- Before I pulled the motor from the wrecked vette I made sure it ran and had nothing wrong with it. Since then ive completed the transplant using a speartech harness and the motor fires then shuts off after 3 seconds. I planned on doing the tuning myself with the help of a buddy and I figured it was the VATS that was shutting the ignition off. So I ordered software from CATS and dissabled the VATS. Same problem- Fires right up the shuts off after 3 seconds. Any ideas?

[streetk14]

You might want to start by figuring out if the engine is losing fuel or spark when it dies. If you have a fuel pressure gauge that would be a good place to start.

Andy

[scotzilla]

i dont think its a fuel issue- it cuts out nice and crisp like its cutting spark. It will rev as high as i want when i fire it then shuts off. Ill check it out just to be sure

[hotrdblder]

the college budget kid had the same issues, forget them name of his thread, same motor etc

[scotzilla]

got his username- I search for college budget and couldnt find anything

[shep]

His turned out to be the coils I think.

[scotzilla]

odd- wouldnt that throw a code?

[MuscleRodz]

What about the oil pressure saftey switch? If it is not reading pressure it won't allow the engine to run.

[scotzilla]

i had that thought now that im home- Ill try and jump it for a second and see if thats it

[scotzilla]

there is no harness or terminal from the speartech harness to go to the oil preasure switch- So i called speartech and the tech says they dont use it and that the oil preasure cant shut it off? He thinks its the vats. I guess ill call CATS. Does anybody know for certain that the oil preasure switch can cause it to shut off?

[MuscleRodz]

there is no harness or terminal from the speartech harness to go to the oil preasure switch- So i called speartech and the tech says they dont use it and that the oil preasure cant shut it off? He thinks its the vats. I guess ill call CATS. Does anybody know for certain that the oil preasure switch can cause it to shut off?Has the pressure switch code been removed from the computer? If not, by not hooking it up would make the computer think it does not have pressure there for shutting the motor down. It bypasses the code to start it and then turns it back on after it has been started.

[scotzilla]

i never removed it so probubly not. Its got 45 psi at the fuel rail- Its cutting the injector and ignition at the same time. I thought with vats you cant re-fire a car for 4 min? Im getting so much different info from experts i dont know what to believe

[scotzilla]

well ive tried over a dozen times to load the new tune and it seems its loading in the ecu but not taking- Another local tuner has told me that 95s are a transition year with obd 1 and obd 2 and sometimes they do wierd stuff like this. Hes sending us a tune from different software and we are gonna try and use cats to load it. If that doesnt work im just gonna send the ecu to spearhtech and have them check it out and tune it.


Also is there a way to check if the tune is loading in the computer- I heard if the map and maf sensors are not plugged in then the engine wont start at all. we unpugged them and it runs (not as crisp, but runs) and shuts off the same- We changed it to speed density hoping to be able to tell if what we are inputting is taking in the computer. i cant think of any other way to do it

[MuscleRodz]

i never removed it so probubly not. Its got 45 psi at the fuel rail- Its cutting the injector and ignition at the same time. I thought with vats you cant re-fire a car for 4 min? Im getting so much different info from experts i dont know what to believe
If the VATS was the problem it would not let the car start period.

[scotzilla]

are you sure cause i put remote ignition on my 94 wagon and it did this same thing until i disabled vats by putting a resister inline

[MuscleRodz]

are you sure cause i put remote ignition on my 94 wagon and it did this same thing until i disabled vats by putting a resister inline
Are you using LT1 Edit? Is your computer OBDI or II? If you are having issues getting the program to load, I would send it off and make sure the computer has been properly altered. Has to be the issue if everything worked before.

[Mayhem]

I thought the college kids problem was with the starter wiring. one of them dropped 12v after starting and did not allow it to run. I may be wrong on that. was his name camarokid or something?

[Mayhem]

I was close he was 69camarokid. here was the link. Hope it helps. He spent a lot of time from what I can tell chasing the VATS when it was not the issue at all.

https://www.pro-touring.com/forum/showthread.php?t=42389&highlight=camarokid

the post at the end said:
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the engine is from a 95 trans am.

well with a little more inspection it turns out for sure that the ignition wire has power to the pcm while cranking, but upon start up the pcm stops sending the signal, which is, according to the GM wiring schamatics, supposed to send the signal to the other half of the brain, nad from there to the ignition module.

my mechanic thinks he found a way around it with some help from some people on this forum, so thanks guys. hopefully it wil be up and running in a few days.

[scotzilla]

i put a ecu from a 96 impala ss into it- Acted the same except cut off after 1 second instead of three- SO i knew it was a ecu problem- We dissabled VATS on it and it runs now. Still dont know why CATS wont dissable the VATS on a vette computer-

so problem solved- maybe move this to another section but I would like to still figure out whats different about the computers and why the vette ecu wont take it.

[scotzilla]

well we loaded the file from the b body into the y body computer and it runs. So now we are working on transfering over the fuel and timing tables. What else is different between the two tunes?