Throttler

So my 01' Trans Am WS6 stock 5.7L LS1 has been having an issue with stalling out some time after the car starts, usually just enough time to get me a few miles from home, and then won't re-start, it just cranks and cranks. If I leave it sit for say maybe greater than 8 hours, it will start up again just fine. So reading thru the interwebz, I've begun to suspect the crank sensor, and took some measurements with an oscilloscope to try to confirm that this is the issue before I just start replacing parts randomly.

I would like to know if you guys think that the crank sensor is the primary culprit or something else.

Video showing what I presume to be a normal trace of crank signal


Video of the car stalling out ( I can't beleive I was filming when it happened!)


Here is a cranking attempt from inside the car after the car stalled out


Another cranking attempt this time measuring the crank signal


Video of my o-scope setup

wait4me

iTrader: (10)

Dumb question, but is the fuel pressure there? Check to make sure Fuel pressure. I saw a condition like you are saying and it was fuel pump going bad.. Or relay on one car.

Throttler

I tested the fuel pressure previously and it was 53psi during initial prime, then 56psi while running and all thru the stalling out, and was in that same range while cranking afterwards and not starting. Thanks for the input!

wait4me

iTrader: (10)

Hmm well, a sensor is cheap enough, Just pull the starter and try another.. Check for burnt wires while down there.

joecar

You need to increase the time base and capture more signal, then compare it to this (you need both CKP and CMP so you can compare their relative positions):

the crank reluctor is divided into 4 quadrants, each quadrant has a unique sequence of wide (12°) and narrow (3°) pulse pairs.

Throttler

Replacing the crank sensor I believe fixed the problem.