They still touch the PCM, just not the performance settings that were flashed into it. Running two different tires like that, it would get expensive real quick to have them do it twice a year though. Or, just flash it for one size, and compensate for that when your figuring your MPG while your running the other size tire.

 

The speedo calibration is actually stored in a module behind the dash, so he would have no way of changing that. It is in one of the modules on the data bus and is still accessed through the obd 2 port. Section 8e- page 9 of the service manual(Merry Xmas)will show you the bus and the different modules. If you have a programmer, return your pcm to stock before having it flashed. Then, if you can find one, get a pcm from a junkyard (probably $50), install it, and program it and set your tire size. Then take it out and install your flashed pcm. Whenever you change tire sizes, swap them out and do it again. If I had understood this before I had both of my pcms flashed, then I wouldn't be stuck with a very expensive Superchips code reader.

 

I see, thanks for clarifying mopowar. So then for me, it should be possible to have the dealer do the tire calibration without any risk of them messing up my B&G flash, right?

 

Yes, they can change it without messing up your flash. Just make sure you tell them in no uncertain terms that you want no software updates or anything else done. I have heard horror stories about people have thier pcm updated without askng for it. I think the Snap-on mt2500 will do it as well, so if you know of a shop you trust that has one, ask them about doing it.

 

I had my local dealership reprogram my PCM for my 35's and they didn't charge me. But I had also just paid them $90 to flash my Mopar performance PCM 4 weeks prior.If youare in good with your service advisor they might do it for free if you are paying for another service.

 

Hey silver, I sent out my PCM out today USPS Next Day and I should get it back before the end of the week. When they send it back, is it in the same box? Do they give you a spec sheet? What if you make any changes to your truck, do you have to send it back for a reflash?

 

Why not use a superlift tire compensator? You can set it for two different sets of tires, and it's independent of your PCM. While more expensive than a flash, it gives you more flexibility. Just my .02

 

I really went deep into my motor and a PCM flash is the only way to squeeze out all the hp I can get.

 

Here is the mileage update on the last tank (really the first tank I have tracked mpg since the B&G install). I used to average about 12-13 mpg for mostly city miles. This last tank was 10.56. About what I expected considering I had my foot in it a lot. I'm trying harder this next tank to drive like a normal human for 200 miles, and see where I am on the next tank. I also used to get about 14-15 for highway mileage, so next highway trip I have, i'll see how that changes, if at all.

 

Hey Silver, when you received your pcm, did it come with a spec sheet?