Im posting this for a friend. He has a 99 vette. And he just put some headers on it and removed the air pump and it won't stay running. It will start fine and run for 4-5 seconds and then it just kinda slowly dies. It doesn't just quit all of a sudden its kinda slow to die. It sounds like the motor just runs out of fuel. We checked all the fuses and they are good. We also plugged the air pump back in that didnt help, and he disconnected the battery overnight and tried it again today and it's still doing the same thing. what could be wrong? there are no security lights coming on. thanks.

 

Not sure if it will help but my camaro ran like crap at first on first start up with long tubes. With mine it stalled out a few times then it started to idle fine. Maybe the pcm is still doing the learning curve.

 

well im one of the guys that put the headers on last nite well pulled the intake back off and noticed that the lil vacum line was off put it all back together and still tha same thang starts up idles to 1200 starts to idle down seems as if it runs out of fuel......when its dying it diesels 2 or 3 times right befor it dies any help would be appricated thanks

 

EGR valve not sealing up well creating a vacuum leak?

 

also could be an issue with the o2s or ECT sensor

 

i own the car in question. heres the thing if you give it gas it will rev but then it dies it also seems to die more abrupt (less diesieling) car will refire and then dies no knocking no codes no gas fumes like its rich, even if o2s i think throttle would make it run,diesel longer or something and it does not. thanks for any help

 

check your ECT sensor, make sure none of the plugs are cracked and none of hte wires are cut.

 

hte ? is that for the egr

 

hahhaha, sorry i cant type, should be THE, just make sure there arent any wires in there that got cut on you during the install.

 

damn i thought it was something i hadn't checked yet hahahaha. we've looked this thing over for three days with a lift from top and bottom all wires look good no unplugs or bare wires all good fuses. tomorrow i guess tech2 at the dealership to check vats and se if it locked us out

 

This sounds like a a/f issue. Your car should be driveable with just LTs. No other significant mods? 99 vettes have an electronic Throttle Body? On my 98Z or cable driven TB I can do a IAC or Inlet Air Controller reset by disconnecting the cables from the TB and putting the car in the start but not turn over key position for 10 seconds then off then start up. Just a simple shot in the dark other than something broke.

 

we went through several unpluggs and replugs of fuel components using ls1 techs search feature.other mods are slp loudmouth, ls6 intake ,cai and thats it the lts are only new mod. when you had your problems would the car run or even rev if you gave it throttle ?

 

are you SURE you didnt damage the ECT sensor on the driver head? that is a very common problem, breaking that, makes the car pig rich so its hard to start or stay running at that.

 

ditto..

 

Where are you at? You need to get a scanner HPT, EFILive, etc. to go any further. If you have gone over the car and have not found anything "broke."
Oooddles of folks running LTs w/ no problems. Sorry I don't have anymore ideres.

 

damage any fuel lines? definately should do this after a header install... kinda odd

 

i think it is the vehicle anti-theft system going to check over car again if i can fix it tonite dealership gets my check tomorrow. thanks for all your help

 

ok checked ect sensor all is good checked plugs no gas soak. car starts runs a little while and then dies now heres what we just noticed/ car dies we turn the key to start it takes exactly 3 seconds before car starts again

 

vehicle anti theft system shutting off injector pulse is the problem. gm tech still trying to fix computer.

new question: im getting a cam installed and car tuned(hp i think is what this shop uses) thursday do you think this will happen again. only two theroies me and black1999-z28 can come up with\
1: airpump delete done with battery unhooked and then when battery reconnected the computer saw the missing sytem and freaked/or
2: we did have some arching from the starter wires at first due to nuts not being as tight as we thought they were but there tight now

any insight, help, opinions, are welcomed thanks

 

Definitely not #1. The arcing isn't a good thing though.. Sounds like a communication disconnect between the PCM and BCM - why, not sure.. Either it dumped it's VATS info or one of them (or one of their related circuits) has fried as a result I'd think.