Hey guys, been trying to figure out an extended crank, backfire, no tach issue for a while now and could use some help.
Some breakdown
Ls7 engine wet sump ls3 front cover, cammed (ls7s), longtubes
e38 ecm (12633238)
PSI Harness (har-1035)
DBW Pedal (10379038)
Throttle Body (217-3153
MAF (213-4222)
CMP (12591720)
CKPS (12585546)
Speedhut freedom canbus gauges
Sooooo, I get the engine in and try to start the vehicle and it has an extended crank and is backfiring, but does eventually start up. Go get the car tuned and dyno'd and it does great (520whp) but the tuner is having problems getting rpm signal and cannot perform crank relearn. I figured i would look into it, the car is setting codes p0315 crank relearn and a p0336 ckps performance. Try to do a relearn with the tech2 and can not get passed the "start engine and let idle" screen. Attempt to do a relearn with the vcm scanner and it seems like i did (hit fuel cutoff). Shut the car off and restart and the p0315 is still present can not be cleared. Me and some of my buddies do a bunch of testing, swap ckps, swap cmp with no luck. Hook up a tech2 and monitor ignition data and find that the ckps active counter is only incrementing when the vehicle is cranking. Once the vehicle has started it stops incrementing. Everything seems to be working sensor wise so we try a new e38 pcm, that did not work either. It seems like my tach problem is directly related to the ckps active counter because when the car is cranking i can see my tach bounce around 250rpm, but then drops to 0 once the car is running. This also seems like it may be causing tech2 fail crank relearn as well. Has anybody ever experienced this?
Tune and some videos attached. Thanks!!