My fuel saver/mds light would go off at 52 mph. I was adivsed to have the PCM refreshed according to service bullein 18-019-09, July 1, 09. I did this and now the fuel saver light will stay on 58 mph. Before it was 52 mph.
I was advised that there would be a bigger change than this.

Would my rear end ratio of 3.21 have any influence on this?
Thanks,
Jack

 

All depends on the load the engine is seeing and how consistant you keep your speed, which way the wind is blowing - doesn't have much if anything to do with speed. I've got 3.21 gears and the fuel saver light is on in the mid - high 60's on flat ground, not on much in the 50's for me.