Stalling and cranking issue
 

I'll be the first to admit that I am not the smartest person when it comes to working on my LS1. I have completely run out of ideas on what exactly this problem can be.


For starters it is a swap car tuned with HP tuners and VATS disabled.
MODS as follows:
102mm TB and IM
long tubes
3in exhaust
cammed
descreened MAF
walbro 255


I have replaced Crank position sensor.
Cam position sensor.
MAF
IAC
and a couple others I may be forgetting.


The car would run perfectly fine for a little bit. Then I had some issues.
First, I got on it and at the top of second poped the clutch it but it just sat at 6k rpm foot off the gas and in neutral.
Second, (this has happened three times now) I get on it in 1st, and 2nd, at the top of second as I shift into third the car bogs and immediately dies. Afterwards it wont crank. To get it to crank I had to swap in my 2nd PCM and reflash my tune onto it as well as replace fuses.

Any help I can get with this would be great.

Since this is cleared with PCM/tune manipulation, it looks clearly like a software issue and not a mechanical one.

Moving to PCM Diagnostics and Tuning. I expect we'll get some additional views and opinions there.

also worth noting that under WOT acceleration the tach jumps up and back down to where it should be sporadically. And now when I plug in my HP tuners it times out and wont connect to the PCM.

Erratic behavior sometimes indicating the ECU is not fully plugged in to its harness. Something may have gotten jostled at WOT.

could the PCMs ground to the car also cause such behavior?

You've got a bad ground or insufficient ground somewhere. Do you have ground from frame to engine to body? Check them all. If they're good, get a scanner that can log real time parameters and watch what the voltage is doing and what the IAC is doing. Have you messed with your throttle cracker and follower in the tune?

could this be a VATS issue? I got the vehicle running. Drove it for about 40 miles. Now that it was back at my house I washed it then tried to pull it into the garage and then It fired and died 3 seconds later. Now it just turns over and I cant connect to the PCM with an OBD2 reader or HP tuners. It says unlocker failed. timed out or something along those lines.