Friend of mine has a 93 LT1 that starts up fine, runs about minutes, and then just dies. I was going to hook up my Autoprom to try and see what's going on, but I thought I'd ask you guys what would be a good thing to monitor for those 5 minutes? Any hints?

 

Fuel pressure and spark. Is this new tune or engine combo?

RBob.

 

Not a new tune.

He just called me and said he cleaned the air intake and it ran for 10 minutes. Gonna go take a look. I'll share later.

 

So, went over, hooked up the Autoprom, started the car and monitored. Sure enough it ran about 5-7 minutes and then sputtered and died. Checked fuel pump, fuel pressure, spark....all there. Started the car several times and monitored; it would run about 5 minutes and then die.
Then noticed that Coolant Temp was always reading -39.25°C...that seemed odd, so I shorted across the leads and sure enough the Autoprom indicated that temp went full scale the opposite way (~151° or 155°, don't remember). That was good, it indicated (more than likely) that the leads, computer, and autoprom were working ok.
Anyway, shorted across the leads, started the car....runs forever. Hooked the temp sensor again...it dies. Hook up the shorted leads and it runs forever.
I didn't realize a failed-low temp sensor would make the engine die that way, hmmm. He's going to change the sensor and let me know.

Does this make sense?