2005 Exp reprogramming

Hey;

Since putting on a set of P265 / 75 R16 tires, occasionally, I get a transmission issue. Starts out like a growl similar to a wheel bearing failure, and usually at the same time, an upshift.

*could* be a trans issue, but from a LOT of reading here and the other forums, I am thinking maybe the shift points are wrong due to the tire change.

I am going to chronicle my efforts to get the software end squared away.


Here is my math:

P265 / 75 R16

96 inches (drivers side rear)

1 mile = 5280 ft x 12" = 63,361 inches

63,361 / 96 = 660.01

660.01 Revolutions per mile


This sound right?

Also, is this that much of a change revolution-wise from the stock rubbers?

Thanks,

-Shawn

 

[High_Order1]

heh

Internet's great. I am literally posting from the lounge of Dean Stallings Ford. I went to the Ford dealerships in Lenoir City, and Harriman. LC said it can't be done. Harriman said it can't be done, then another guy came in, heard the conversation, and said, well, we can try it, but it'll take you a week for us to get to.


Oak Ridge (DS Ford) said they might could do it, but I'd have to schedule. I left, headed to Knoxville, and a friend of mine said she had a friend back at Deans. So she called, and now here I am.

The transmission tech says that it may not accept the program change for the wheel size. He says it is an emissions control issue, and that it (whatever it winds up being) will only accept a narrow range of values.

He also says he isn't sure that the 05 will accept revs per mile (so, there went that work out the window). He says he will look the new tire up in a chart, and see if the module(s) will accept that figure. If not, he says he will load the closest number.

He then asked about what the issues were, and wanted to lean more towards the bore issues. He was *very* surprised that I knew the words bore and epc (THANKS explorerforum), and said he hadn't seen many epc issues here, but that the worn bore was very common around here. (There are a BUNCH of explorers running around Roane/Loudon/Anderson/Knox)

So, he said he would try to shoehorn the number in, and I reminded him I wanted a flash upgrade, and he acted like the service writer didn't mention that. But, he said he would do it after I told him I was told it would help solve the tip-in issue. (Again, thanks!)

So, I will update when I learn something else, including who to talk to down here if/when they take care of me....

-Shawn

 

[High_Order1]

Biggest tire he says can be loaded into the vehicle is 255. He says that there is about 40 revs per mile difference between the 255 and the 265 that lives on the car.

He says that "they say you can put revs per mile in there, but if it's bigger than what it will accept, it'll just kick you out"

I asked if he was able to get the flash upgraded, and he said that it didn't show a newer one was available, but the current system (on a pana toughbook, I noticed) would automatically load the newest flash in.


He is going to road test it, and says that it will shift funny until the trans learns the new changes....

 

[High_Order1]

Well,

I drove it home. Then to a project in the next county over and back. I want to say it runs better overall, but I don't have any real metrics to support it.

The tech told me to check the mph difference using my gps (DUH - why didn't I think about that).

I wasn't able to check it before, so I don't have a base to refer to.

I am having trouble determining what its' doing now. Apparently, my cruise is broken. I never use it.

So, trying to hold steady in the rolling hills of East Tennessee, it kinda appears that the faster I go, the worse the difference between true and indicated becomes.

At 70 on the dial, it appears to be between 71 - 75 MPH actual. At 45, it's fairly close.

So, I don't know if it's off enough to affect the shift points now.
And, I don't know how to tell what calibration is currently in the PCM.

So, that's pretty much it at this point. I am going to research if there is some sort of low-cost flash tool or other way to bitbang the PCM flash to expand the high end of the tire size number.

Hope this was a little helpful:

1 - you CAN get the tire size changed.
2 - you might NOT be able to get it changed enough.
3- without your own passthrough tool, and a lot of specialized knowledge, there's no way to know anything more than what others tell you.

-Shawn

 

[High_Order1]

Ok, to end this thread....

660 is exactly close enough for those tires.

You can force this number in with a SCT Xcal 2, no sweat.


-Shawn