Thor Forums

[HaRVey]

First, as to the OP''s question, yes I used a 5-Star tune on our 2015 Thor ACE 29.2 and I loved the improvement in power, transmission shifting (less frequent and dramatic down shifting and high RPM engine review and noise up every little hill) and did get ~10% mpg improvement (always hand calculated over a year before and after).
Second, any engine that is tuned for maximum efficiency through timing (advance curve) and fueling (leanest without detonation) will produce more power with less fuel (the factory tune is not optimized because Ford does not know what coach the RV manufacturer is going to install or what environment it will operate in), AND the same ECM controls the transmission which is programmed for soft/early shifts assuming consumer preference for smooth, undetectable shifts which allow's for a lot of slippage in the transmission, which equates to wasted power and increased wear. Optimizing both the engine tuning and shift points contribute to reduced transmission wear (firmer, quicker shifts) and increased efficency. By the way, the standard 5-Star tune is just 87 octane tune, so no need to run anything more and I never had detonation/pinging even on 110° days at 4000'!
Third, the Magnusun-Moss Act prohibits a manufacturer from denying a warrenty repare for a modification unless it is specifically the cause of the failure (i.e. can't deny repairing the AC or other non-internal engine part because you added a tune ). If you go to court, the manufacturer must prove what you did caused the failure or else they are liable for your atourney fees too. I brought my RV to Ford multiple times for warranty service and was never denied (I always removed the tune first so it wouldn't be overwritten with a factory update). If you are dealing with an adversarial dealer or service center, I would find someone else...