Hey guys, is there a tool out there for these cars to change the calibration to account for different size wheels/tires. I'm not worried about it too much as I would never run any wheel/tire combination that wasn't for the car but I'm just curious on this. I think I read where these cars have some sort of sensor by wheel or something to account for speed.
Sct and Diablo hand held tuners used to let you change vehicle settings like that.Not sure if they still do.Someone here will know.Ford let us change settings for different size wheel tire combos but no more.They say it changes vehicle emissions calibration,and that's against the law.I purchased a steeda cold air and tune on a sct tuner and the package says not legal for highway use.Oh my what do I do?I could not begin to count how many F-150s and Navigators came in with 20 and 22 in wheels and we changed the settings until they made that unavailable.Salesman would sell a vehicle in Fl and cust lives in Canada.Well they run daytime running lights.We would program Lighting control module for that function but now you have to get a approval from Ford tech hotline to do it.
I got my SCT-X3 from VMP, along with my custom tune already programmed into it. He unlocked loads of stuff, including allowing for a huge range of different tire diameters. The change is entered as "revolutions per mile". They give you a ton of em to pick from. Then I just go to the NITTO site..and see what they list for rev per mile for my Nitto-555 in my rear 275-40-18 tires. Then just tick off the same info in the SCT-X3. Then the speedo is dead on. I change the 4 x rims + tires in late oct... and switch to 235-50-18's ( NITTO Motivo's) for the fall-winter. The speedo is a tiny bit off, so can easily correct for the winter rain tire setup. http://www.vmptuning.com/pics/AutoUserAdjust.jpg You will see the last item listed is for tire size. 2nd to last item is the rear end ratio.
Dunno why emissions calibration would be affected. FRPP sells a mech device, that will allow you to factor in plus or minus 10% of a rear end ratio. ( up or down one gear size, thats it). What it wont do is allow you to swap from a 3.31 to a 3.73 The rpm's will all be way up. The ecu then thinks the auto tranny TQ converter, etc is slipping, then ecu throws a wrench, puts car in limp mode etc. The only thing the FRPP mech device will fix is your speedo, and only if the rear end gear ratio is changed +/- a little bit. Nobody uses it. Easier to use the SCT-X3, and do it all in software. Then you can use any rear end ratio- tire diam you want. But the front and rear diameters still can't be more than 2% apart, or your abs brakes will be affected.
Yeah, I know about the handheld tuners being able to change those calibrations but for me being stock as far as the power train (RS1), I'm sure they would try to void my warranty just for a simple calibration like that, if anything were to go wrong. I think it's dumb that Ford can't even change these parameters for us, especially for those of use wanting to keep the car as stock as possible. My suspension won't be stock soon but I could care less about warranty on my suspension components.
In a couple of years I won't have worry about any of this. Well, I guess it can still be an issue if I care enough about keeping my 7 yr 100k mile powertrain warranty I got for buying a Ford certified pre-owned vehicle. It actually blows me away that I get better warranty by buying a used car vs. a brand new car (5 yr-60k mile powertrain from Ford).
You'd be better off believing you can retire by buying lottery tickets. The 'warranty' is only worth about as much as the integrity of the service manager you happen to talk to the day you have a claim, and they are trained to deny claims. Whatever might happen to your car that you think might be worthy of a claim was caused by something else which isn't covered. That's the way it works. Warranties are a sales tool.
Good point skwerl, I've never really thought about it that way. I've had issues in the past with other cars where I had modified something and where the issue was unrelated and they tried to blame it on that. Needless to say, they denied warranty. On my SRT-4, I lowered it, and my front axles started to click when turning and they blamed my lower suspension. Most of what I had heard with axles going bad had to do with wheel hop with that car. Of course, try convincing them of that.
On the Mustang, the only true modifications I have as of this moment is the Barton STS with bracket, and axle back exhaust. Technically they can try to blame those mods for failures with the transmission or engine, I guess.