Since > even if I do ever get an aftermarket tuner < that is going to be sometime down the road, I'm trying to find out about having the onboard stock computer reflashed, to correct my speedo / odo readings, and more importantly, shifting points, when the truck is fitted with larger than stock tires.

So, I just called one dealership and spoke to a lady (okay, I'm sure there are some female service guru's out there somewhere, but this one didn't give me that impression) who said that >
"they could reflash my computer to correct for the speedo and odo readings"....... So, when I asked about shift points, she replied, "Oh... Yea.... it corrects for all of that in one shot, just as soon as it takes the new tire size into account". Hmmmmm. That sounds nice, but I'm skeptical. Is this true ?

So then I ask her how much they charge to reflash a computer..... 2 hours at $115 an hour.... for a total of $230 ! To which I replied, "$230 for a 15 minute job" ?

What's the real deal about having a stock computer reflashed ?

BTW, she did say one thing that sounded logical > The stock computer can only correct for so much of a tire size increase, and if you went WAY over the stock tire size, they may only be able to partially correct for it < Well, I'm hoping my 33.7 tires are not so extreme (only two inches taller than those on a Lariat) that they can fully adjust the computer for them.

Who can tell me more about the reflashing of stock onboard computers ?

Thank you,
Fish

 

You have to also use the gear ratio to scale down for that to work with the stock computer. Most techs are 'tarded and won't get it.

 

are you saying then, that it's possible, if one could find a dealer tech that had a clue ???

Thanks,
Fish

 

Yes, make sure they DO program the thing with any gear ratio change you install as well as the tire size.

Once the PCM has both those settings, it can adjust your shift points more or less correctly, since part throttle shift is simply a function of your vehicle's speed and your accelerator pedal position. With the correct gear ratio and tire size, it will "see" your speed correctly.

But, I said "more or less", because the PCM is going to be operating on a schedule that is "canned" in the firmware. With larger tires and a different gear ratio, you may not want it to shift at these canned points. That's where a programmer comes into play.

- Jack

 

It only takes about 25 minutes and they normally charge about $80.

 

Yeah, I made a quick spreadsheet for someone on here before on what to set the gear ratio and tire size too. I will see if i can find it.

 

that would be GREAT info to have ! I'd totally appreciate that....

Oh BTW, do you think the stock computer will be able to correct for 33.7" tires ? That doesn't seem to extreme to me......

Peace,
Fish