[Power Hungry]

Originally Posted by cleatus12r

Normal operation.

The Hydra will not switch to "00" bypass mode without a key cycle. This means a change to "00" needs to be made, wait for the blink, then turn off the ignition. The next power-up will be in bypass. The chip WILL switch from bypass to any of the loaded calibrations without a key cycle...it stalls/stumbles because the calibration on the PCM does not match the calibrations on the chip. This is normal and nothing to worry about - just don't make a habit out of switching between "00" and other calibrations while the vehicle is running. If you must do that switch WITHOUT the engine running turn off the ignition and restart.

An unmolested (not updated by the dealer) VDH4 computer will have a calibration of TNAA5S8. If it's been updated, it's probably TNAA7S5.

You are currently running TNAA4S2, which is perfectly fine and what we normally recommend. However, if you'll notice, the first 5 characters of the calibration are not the same, particularly the 5th digit. The first five characters calibration indicate the Operating System build of the calibration with digits 6 and 7 reflecting the tuning revision. If the first 5 characters are not identical, then the calibrations have structural memory differences and therefore generally cannot be switched between them without causing a computer hiccup. Some calibrations have more changes and may experience more severe stumble or stall while other have fewer changes and may not experience any negative effects at all. It all just depends on the changes.

For all intents and purposes, there's really not any reason to go into [00] unless you need to perform some sort of diagnostics and want the tuning completely out of the way. Outside of that, just keep the Hydra in a tuned level and you shouldn't have any issues.

Take care and Happy New Year!