Hey all,
I need some desperate help with my 2018 GMC Sierra 1500. A few months ago, I had the dreaded DOD lifter failure that resulted in a bent push rod. Being that the original L83 5.3l had 85k miles on it, I decided it was a good time to swap in a low mile L8T 6.6l that i had sourced. Along with the L8T, i added a BTR 220 cam and the required springs. Being that the oem L83 intake manifold would not work on the new L8T, i picked up a ported L86 manifold and ported LT5 throttle body from Chuy's Porting & Performance (454Chuy) out of TX and ordered a set of long tube headers. To tie it all together, i purchased a yank 3600 stall converter.
I reassembled the L8T and dropped it in the truck. The truck started right up on the OEM tune. I had my tuner set up a base file so i could drive the truck to him and also drive it around to ensure everything was 100% prior to the dyno tune day. It has been a few weeks of driving the truck and i have sent a few logs to just make sure things are good. Last night, i contacted him about them and he mentioned that there was an issue with the cam sensor. The BTR cam is supposed to be locked out at 0-4* with a phase limiter block installed, but the VCM scanner is showing 16.9* constant. The desired angle is zero but it is stuck on 16.9*. Cam angle error is also at 17* so that coincides with the angle being seen.
The truck idles and runs decent, although it does bog and surge (like its misfiring from time to time, especially at part throttle). I know the mechanical timing is 100% right. i took pictures of it, along with videos and even measurements ( as i had the phaser jump before causing the timing to be off). The truck is throwing a P0341 code for the cam sensor, but when the phaser jumped last time there were 3 cam codes and the truck wouldn't even start. I know this is more straight tuning help here, but maybe someone has some thoughts through some experience?
Could it possibly be that the cam position sensor has gone bad? Would that be a reason to have the angle being read at 16.9 and stuck there? Would a crank relearn help? Is there something in the channels that isn't right and causing it to read like that?
I'm really at a loss here. I would double check the mechanical timing, but that requires pulling the motor again and that is a huge process. Plus i can't see it being that as i spent extra time confirming it to be 100% right prior to reinstalling this motor. I'm hoping it is sensor related somehow.
I've attached the log and base tune so everyone can see what I'm talking about.
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Originally Posted by Camaro6
