My dad and I have been working on my car to 2 weeks now and can't get it to stay running. It will turn over but won't stay on the longest it's idled for is about 20 seconds. We have replaced the fuel pump, fuel filter and check all the fuses. We have also used a code reader and no codes have came up. We also have good fuel pressure so what could be the problem.
How many miles on the engine?
Has there been any engine work done lately?
Have you looked at the spark plugs? How do they look? Post pics.
Do you have spark at each cylinder?
How about posting a short sound/video for us to listen to?
Have you done a compression check?
You may want to check your throttle body butterfly plate. If there is any carbon build up, it will throw the ecm off. I had this happen to me on several cars and each time it turned out to be the problem. Two weeks ago it happened in my WS6. It will not give you any codes if it is sticking.
Check the idle air control valve. If it's gummed up and sticking, it could cause this problem.
Also check for any security codes. Although on LS1's usually the car won't start at all if there's a VATS issue, I know that on other GM vehicles of the era, the car will start but not idle if there's a security issue.
The only thing that causes my 1998 Trans Am to literally not be able to stay running:
1) Gauge Cluster not installed
2) Bosch 02 sensors installed
My engine will literally backfire, misfire, shake and then stall in both of these situations. ALSO...I have, on two occasions had my Coolant Temp Sensor unplugged and the engine runs terribly and barely stays on.
Check to see if that Coolant Temp Sensor is still plugged in......
The other two things above don't sound like the culprit. Is your gauge cluster working normally.....?
You might want to try to start it.....as someone else grabs the big wire bundle coming directly out of the PCM....over by the passengers side strut tower. As you are starting it, have them move that wire bundle in all directions.....the ground wire inside that bundle may have broken. It happened to me once and it wouldn't let the engine stay running. A guy came to my house, knew exactly what it was.....he cut into the bundle and pulled the wire out. And he grounded it to one of my valley cover bolts. Started up and ran perfect.