All tuners who use a tuner to flash the engine with custom tuning will have this issue, it may also be an issue anytime the ECM is reflashed either with a factory flash or other aftermarket tuner. The issue has been found using EFI Live so far, but we anticipate this to be the case with any flash or tuner . This issue may also occur with HS and other platforms as well including factory flashes, but we have not tested it and cannot be for sure, but we expect it to (more on that to come). The issue is more problematic on the 2010+ trucks as the TCM and ECM are combined and therefore when the engine is flashed the transmission side of things gets disrupted as well even though no change may have been done to the transmission. The 3rd gen trucks have separate controllers and therefore the issue only arises when the TCM is reflashed.
So, unfortunately we have found that on all 2010 and newer trucks there is a major issue that occurs when the controller is flashed. When the unit is flashed the transmission’s CVI adaptive memory is erased and put back to stock. Basically, the truck thinks that it has a new transmission installed in it when it does not. An example is a truck with a performance transmission starts with a baseline OD CVI in the 45-55 range normally. After the drive learn portion this CVI number goes down to 5-25 in most cases. The controller can only adapt a point or two per shift, so if you don’t give it time to adjust a failure will quickly occur. The more power and line pressure the lower the CVI number usually winds up. Hence when a high HP truck isn’t given the chance to readapt the transmission can be destroyed in just one shift!
When the adaptives are reset, the transmission simply is out of sync with the controller. The transmission has X amount of wear in it while the controller is telling it has Y amount of wear. What happens is the shifting elements (clutches) are basically being applied with the incorrect amount of timing during the handoff when the off going clutch and on coming clutch are being released and applied. This can result in a flare or a bind during the shift. If this occurs at light throttle nothing bad will happen as the transmission TEACH the controller to slowly RELEARN the adaptives to where they need to be. This normally will take few dozen light throttle (less than 30%) upshift and downshift sequences and the adaptation process will be done.
If the truck is driven hard after the reflash and the transmission is not in sync with the controller, it will lead to transmission wear. In extreme cases, just one shift like this will completely destroy the transmission. The more power and throttle input the bigger the issue will be.
The next issue is CSP 5 or any other changing of power levels on the fly! When switching power levels you MUST allow the transmission to slowly adapt to the increased power levels. If the transmission is not given time to adapt to the new power levels you will damage the transmission in short order. Simply give the transmission 30 miles after a tune reflash to adapt in stop and go city driving before getting on it and you should be fine!
Frank Kuperman, Vice President of Engineering, RevMax
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