I'm sure I could find the answers to these questions if I searched long enough, but I haven't posted in a while anyway.

I bought a Flipchip from Mike last year and it's been great. I'll explain my mods and then ask the questions.

I added the chip.
I changed my tire profile from 70 to 75
I changed my ring and pinion gear to 3.73 from 3.31
I also added positraction but I don't think that would matter.

Now, my speedo was all wacked when I made the changes, but then I ordered the superchip and had it programed for my specs.

I noticed a little later that my speedo is consistenly off by 5 mhp+. I confirmed it with radar.

Since I was very busy and everything else was great I didn't worry about the difference, however, I beleive that over time this will create a large difference in the mileage my odometer shows, in a bad way if I decide to sell the truck.

My question is: Is the ordometer mechanical or electronic as it relates to the speedometer? Meaning is the distance I drive incorrect as well is the speed? If so, should I have my chip reprogrammed?

Thanks for your help.

Tim

2000 F150 SCab
5.4V8
...........

 

Hi Tim,

First, you'll need to call us for this if we provided the programming for you to correct the speedo for the gear ratio change and the tire size change, as we'll want to go over that, and some other things as well.

Just speaking in general, you're not going to have a "consistent" 5 mph error at various speeds, as speedometer errors are always going to be a constant *percentage*. Thus the faster the vehicle goes the more speedo error, and the slower it goes the less speedo error. For example, if it's 5 mph off @ 50 mph, it's going to be 10 mph off @ 100 mph, for a 10% error (and 7.5 mph off @ 75 mph, and so on). If it's 5 mph off at 35 (say, reading 40 mph at a true speed of 35), then that's a 14.29% error, big enough to throw off shift points (up and down) in automatics.

I wouldn't put a lot of faith in traffic radar signs that tell you how fast you're going, if that's how you're testing your speedo reading, as we've seen them have significant error themselves; though of course some are accurate, many are not. Using a current registered in-service police radar gun is generally pretty darned accurate, that's always the best way to check the speedo. Of course, I don't know which way you're checking your speedo, so I'm just mentioning this in general.

We've seen problems ranging from reflashes to PCM replacement to incorrect gear ratios installed to you name it cause speedo error, sometimes even though we've provided the correct program changes! That is pretty rare, but once in a while something like that will happen, and at this point right now there's no telling what the actual culprit is just yet in your case, we'll need to examine this off the boards.

Yes, if your speedo is off, you're generally going to have odometer error as well, and when the speedo error is fixed, if it was a problem with the powertrain program then the odometer's accuracy is restored as well.

The first thing to do is to call us if we provided your custom programming, so we can work with you on this, etc. give us a call so we can pull your original paperwork & go over all the details, check the program if need be, etc. for you, ok? Thanks!

Talk to you soon,