Forscan Help

[BSouders80]

Needing help with Forscan please.

I got it all setup and going on my laptop with the free extended license. Enabled DRL, dropped TPMS value to 36 PSI, and made a few other tweaks.

All that I've done is through the easy access menu. I've read about the spreadsheet and the as-built.

I also have ALL of the "as built" files backed up before I touched anything.

Now - Where I need help. My Speedo is off. When Speedo says 60 mph, actual speed is around 65 MPH, per GPS (2 units read the same).
In forscan, the largest tire size available is the factory tires. I'm running Mickey Thompson Baja Extreme, 35x12.5x17.
The largest circumference in easy menu is 2652 mm. I tried changing that to 2750, no change, and 2550, no change. Changed back to 2652, which aligns with the 315/70/17 tire size.

I am assuming I'll have to do this through the BCM as built. Can someone help me on that?

Thank you in advance.

 

[BSouders80]

I was not doing the PCM re-learn after changing the sizes. I did that but no change.

I get code U0422 - Invalid data received from BCM.
When I go back to the bcm easy access after refreshing the DTC's, the tire size entry says: Incorrect value or not configured.

I tried the as-built method as well.
Went into 726-045-01-019A-0A5C-0047 and changed the 0A5C to 0B5F. Wrote that, re-learned the PCM and no change.
When I went back into the BCM easy access - the 0B5F changed my tire circumference from 2652 to 2999 and I had the invalid tire size error again.

I'm at a lost. Changed it all back and no errors or anything, but speedo is off 5 mph at 60 MPH. GPS reads 65 mph.

 

[BSouders80]

So from more reading, it looks like that we are limited to the tire sizes in Forscan to choose from.

If that is the case, what is the way to get the speedo correct? I have custom tune. Does it have to be updated in the tune file?
When I go into the tire/gear change size of the tuner, it shows not available.

I've also read about Hypertech speed calibrators.

Hypertech 742502T Hypertech Speedometer Calibrators | Summit Racing

Free Shipping - Hypertech Speedometer Calibrators with qualifying orders of $99. Shop Speedometer Recalibration Devices at Summit Racing.

www.summitracing.com

 

[The Car Stereo Company]

315/70/17 and 35x12.5x17 are basically the same measurement. i dont see how such a small difference in tire diameter is causing your spedo to be off by 5mph

 

[BSouders80]

I’m not sure. It’s been off since I loaded the Livernois tune a few months back. I’ll get with Chris and see if they can look at that.

 

[Canuck714]

I would have your tuner build the tire circumference into the tune file.
But if that is not an option read the ForScan link attached, scroll down to step 14-15 or 16 where it tells you to force a relearn to get rid of the tire size discrepancy code that will appear.
This is the only way to get it to adapt to the new circumference.

Sometimes the manufacturers revolutions and circumference are not as accurate as what the computer detects when the wheel is sending info to the TCM/BCM/ABS modules.
I played around with the circumference number to get my GPS and speedo to be off by 1mph at 70mph...

How to use FORScan to adjust tire size - FORScan forum

 

[BSouders80]

@Canuck714 Please read post 15 in the link about U0422 code and specified range. That’s the boat that I am in.

I got ahold of Chris with Livernois. Provided him with the revs per mile and mfr listed tire OD. I should get a tune update on the near future.

Will update when I make some progress.

 

[BSouders80]

Chris with Livernois got me a calibration for my tune file. At 60 MPH on the speedo, I was running 65 mph per (2) GPS sources. After tune calibration, I am now running 57.5 mph when speedo says 60 mph. So - Progress. I would think one more calibration file and it should be good. I don't need it "perfect". Just within 1 mph or so would be ideal.

 

[BIGW0RM]

Bumping this. I just got forscan. I was able to do global windows. But I am scared to do the tire size change after reading this. Was this a tune blocking forscan issue? Or could I possible run into this if I get 37's on my 35 Raptor?

 

[BSouders80]

I never did get anything resolved with tire size in Forscan. With an SCT tuner, they have an option to adjust gears/tires. Could try that method. With Livernois, the only way to change the Speedo is to get them to make an adjustment in their tune. I've asked multiple times and requested a tune update from Livernois for the the tire size. Chrs Rekuck told me that pretty much it's as good as it's going to get. Since March and that rubs me wrong. They made one adjustment and went too far, now they won't adjust more? They went too far. Go back to original set point and adjust 50% of what the adjustment was.