69CapriceHDTP

HaHa, no. That's my amazing f'ing tune. That's simply cruising down the interstate with a sled deck and 2 sleds on it. So a whopping 15-1700lbs in the back of the truck was all. Talked to Carl at CJ Tunes in St Paul and he says the issue is completely in the tune. Sent tune files and datalog to look at, but he wants the truck for a week to get it all straightened out. 5 hours away.

smokeshow

iTrader: (16)

That's a pretty cool problem. Think I know what's going on though... It sounds like your cam is moving. You don't have enough data in the log file to say for sure, so go ahead and log a parameter called 'Intake Cam Angle' and see if the value is jumping around while this surging is occurring. Looking at your tune file from another thread, the VVT system is still calibrated to phase the cam at cruise speeds to reduce NOx emissions. Unfortunately, the throttle response to cam timing adjustment is no longer calibrated properly due to the blower behind it... My advice is to disable cam phasing entirely, or at least until you can get in touch with someone in your area familiar with the system to calibrate it. For now, set the low, med and high baro tables like this to zero across the board.



There are other potential causes of your surging, but I feel like this cam movement is the most likely. Give it a shot and report back.