I have a gen 3 2001 factory Tahoe 5.3, and the motor was replaced with a 5.3 with a front can sensor cover. The crank is 24x and the cam gear is 1x/factory ls2.
I know about swapping two wires on the cam sensor harness to get it to work with 0411 ecu, however the engine is doing a random no start just crank/turning over with a slight pop out the exhuast.
Things I have done:
Changed front can sensor with another new one to make sure I didn't get a dud.
Ran a sub harness from the sensor directly to the computer.
Ran 12v and ground directly from batter to sensor.
Checked signal being given by can sensor with a scope, wave form and signal look good.

When it starts, it does so instantly and runs great. No problems no codes. But random if you try and start it, theres a chance it just will turn over over and never actually run. If you stop trying to crank it then immediately try again it fires up no problem. Everyone and internet says its the can sensor but no one reads about the application. This is a gen 4 motor with gen3 24x crank, with a ls2 timing set and from can position sensor. I read on the internet that this should be easy and worry free. But before putting this refreshed engine in the Tahoe started every time.

No codes are set, and I am running out of ideas, I was suppose to give this vehicle to kin folk as they move away and I'm on a time limit before they leave. I am this close to pulling the motor and putting a low compression iron 5.3 in it.

I read about perhaps the ls2 cam sensor requires a pull up resister across the ecu input and the 12v feed? Or I saw someone else mention needing to run a ls1 OS. Can anyone point me to any documentation? I am having a hard time finding anything on this. The results for ls2 front Cam sensor conversion just brings up the hardware like what gear, sensor and cover. Nothing mentions what computer or fueling stredegy is compatible with this Cam sensor position placement.

Should I check the crank position sensor signal for integrity? Will the ls2 can position sensor simply not play nice with the p01 0411 ecu?

 

just a thought but with an engine swap, have you confirmed all the other grounds are clean/tight? It may not be the cam sensor at all, could be something else not getting a proper ground/signal until it gets jostled around by a starter enough to make contact. I had a similar issue on mine and it turned out to be a battery cable with just a bit too much oxidization on it...

 

I appreciate the input. I am on the way home now to check crank signal, grounds and OS. Do you have any links or documentation that says this works? That says "Ls2 front timing cover and sensor work in an 0411 application without issues"? I am having a hard time finding anything online.

 

I have done exactly what you are trying to do multiple times now. Each time I try to just "switch the A & C wire positions" it NEVER works that way. This last time I had to find a wiring diagram for the CMP (cam position sensor) on-line, and then re-pin all 3 wires at the PCM to have the sensor work correctly, and not set codes for cam sensor, and to start as soon as you bump the key. Did I write any of that down? No. Should I have written it all down? Yes! But.. do it the hard way, like I have to do each time, and it will work correctly when done. The hard starting you are mentioning is telling you the sensor is not wired correctly. Will it work correctly when you have the wires pinned correctly? YES! It's not a big deal.. Just 3 wires. The wiring diagrams are available on line for the cam position sensor (if you can figure out if they are ID'ng the wires by looking INTO the connector, or FROM THE BACK of the connector). Then figure out where those 3 individual wires plug into the PCM-and you are set! The 4th gen vehicles that left the factory with a timing cover mounted sensor had an additional short pig tail, or wiring harness, that went between the sensor and the factory harness and swapped *some* of the wires around. People will tell you A & C... My experience, and apparently yours as well, is different from what you read on the internet.