So i finally got my car to start tonight, it starts up runs for about 2-3 seconds and then shuts off, try to start it again does the same thing. alittle background info, had a no start condition for awhile, finally diagnosed a bad opti. replaced opti, crank/cam gears, timing chain, and water pump. went to start the car and i had some valves that loosened up, so i readjusted all my valves, and they were nice and tight, went to fire the car up, started up, ran for a few seconds shut off. ive got 42 psi fuel pressure at the fuel rail.

thought i read somewhere about it being an affect of the anti theft system, but when i got my pcm tune it was supposed to be tuned out, and the harness im using also has a "vats delete box"

any ideas? thanks in advance

 

Shouldn't be VATS because of the way you have it set up especially since it starts.

Are you sure its programmed correctly? Does the motor sound healthy for the short time that it runs? Any trouble codes? If VATS is still programmed to be on, it will throw a code.

I'm a little stumped on this one. Battery cables good? Battery connections good and tight? Maybe its something with the ignition like the ICM. It really sounds like VATS but it shouldn't be.

 

Im not sure if the LT1 vats system works the same as the LS1...but my LS acted the same way. Vats was supposed to be tuned out, but it wouldnt run more than the few seconds. So I built a vats bypass box to see if that was the issue. Sure enough.

Now the funny part. I decided to buy a pre-built bypass box, and use it as a security device. Unplug it, take it with me, and it wont start. Wrong...the car started to run without the box. Sometimes it'll fire right up without it. sometimes it wont. Its weird.

If it has air, fuel and spark, and its only running for a few seconds, Ide be looking at the vats system.

J.

 

check the oil pressure switch

 

are you sure your fuel pressure is staying up when the car is running for that few seconds? If you car sounds healthy and then just shuts off it could be you're draining the fuel rail which would make it act like a VATS problem

 

If the car starts, runs good and just shuts off like you turn the key off, it's VATS. VATS would make it drain the fuel rail seeing the fuel pump won't run. Have someone sit in the back of the car and see if they can hear the fuel pump run after it starts. If you have fuel pressure at the rail after the car dies, then I would be willing to bet that is what is going on.

VATS won't throw a code if it is kicking in, at least in the 5 PCM's I've tuned it out in did.

LT1's don't have the same setup that the TPI cars have, only one oil pressure switch and that's for the gauge.

 

okay, guys than for the help, alittle up date, i had my fuel pressure set up to about 42 psi, it would drop alittle during the few seconds of run time, i bumped it up now, and i also found that my MAF was not secured well. it was letting alot of air in behind the sensor. fixed that, and it fired right up, ran well, and then let it sit and idle and it idled for prolly about 15-20secs then stalled. i know im running a big cam, and im not sure how much not having my 02 senors in right now would mess my idle up enough to stall it out. i dont have my exhaust on yet, and i didnt want to drill into $500 headers so im running none at the current stage

 

Brought the Tech 2 from work home, scanned the car got following four codes:
P0018-injector circuit
P0022- tp sensor circuit low
P0077- fan 1 circuit
P0097- 4K pulses

i cleared the codes, fired the car up again, and got the following three codes back:
P0022
P0077
P0097

i was told that the TP code is one that willl prolly just have to be tuned out, since its a big cam, the car doesnt understand why it takes that much throttle to get the car to idle.

i understand the fan circuit code, due to the fact my fans arent hooked up yet.

however im stuck on the P0097 code. i dont understand what it is or why its on, any ideas?

my car idles excellent at about 850 rpm and seems to have good throttle response, havent driven it yet though.

 

code 97 is VSS output which is the speedometer. Have the speedo wired up?

 

no its not, so that answers that question, and does anyone know if the TP code is just one that needs to get tuned out? my friend who had a 98 ws6 with ms3 cam needed to get his code tuned out that was similar

 

TP Sensor I would say is the throttle position sensor, that could cause it to stall out possibly if it's not working properly.

 

i know its the throttle postion sensor, mine works jsut fine, i was getting voltage and percentage increase when i stepped on it, and looked at live data with the tech 2. just dont know if its one that has to be tuned out or what

 

shouldn't' be, I know several that run good size cams and don't have to program out any codes with theirs.

 

alright thanks, sometihng i gotta look into more, the car runs and idles beautifully at a bout 850 rpm now, since i got the injector code cleared and not have it come back