I'm having starting up issues with my ls3 swap I'm using the extension harness they sell for ls1 to ls2/3 style. I'm also getting the dtc p0343. I was told the wires might be mixed up in the extension. Any pointers would be appreciated. The car takes about 3 attempts to start and meanwhile it has backfires while cranking. I have a ls1 wiring harness style on the car btw. And I also have the correct cam gear and 24x reluctor wheel on my crank I got them swapped out.
Thank for any tips.

 

The extensions should be straight though as you don't need to change anything for a gen III PCM to read 24/1x. I'd start by checking to make sure there are no wires crossing in the extension.

I had a similar problem with mine. I only got spark on 1, 3, and 5. Turned out to be a low quality sensor (ICT Billet) that was causing it. Threw in an AC Delco and it fired right up, once I put the intake back on and reassembled the harnesses.

The sensor you have should also be black, and not grey. Not sure if you changed it, but there are two different types 24x is black, and 58x is grey. That will also cause this problem.

 

Today I actually decided to try swapping it around the wires on the sensor extension and the car started right up. I thought they had fixed it since i seen on old threads that they had fixed them but I guess not all of them.

 

Glad you got 'er going! Thanks for the report! Sometimes it IS the simple things, and NONE of us are immune from it!

 

Yup exactly couldn't have said it any better. Now it's time to fix all the little bugs on it.