Rear end ratio and ECU changes?
 

Poking around in the tables and came across this. If this is what it says it is, shouldn't these be changed if the rear end ratio is changed?




I can't get the image to display properly, but it's a table from
Miscellaneous - Thresholds


Gear Determination Thresholds


Gear thresholds Vs Rev/Mile

I think this is true and maybe someone else can back this up. I believe that the speed is taken from the ABS sensors in the wheels so rear gearing changes shouldn't have any effect. How ever tire diameter will.

Correct mate

That is true, but I don't think the table is about the speedometer. It has multiple values that pretty clearly tell which gear the transmission should be in depending on the rotational speed of the tires. 65 mph with 4.10 gears could call for a different minimum gear selection than with 4.88, for example. That's why I wonder exactly what the table does and if it should be edited.

I think that is related to Auto Trans?

I believe that table is to calculate what gear number to display in the dash

if you need to adjust speedo error i believe that can be done with techstream software its got a limited range for speedo correction. you can get the software for free but you will need an J2534 adapter to talk to obd port, unless you have a tactrix cable or ecutek cable .

you can get the elcheapo j2534 adapters for techstream software on ebay, just search for techstream.

dont buy the imitation clone tactrix adapters from china, they are rubbish and likely to brick your ecu buy the real one from e tactrix site www.tactrix.com if you want a tactrix adapter.

Hi,

Gear Determination Thresholds is basically related to the gear indicator in your cluster.
With modified final gear ratio, you'll see unmatched gear number in your cluster. To say, 1-2-3-3-4-5 rather than 1-2-3-4-5-6.

I would LOVE it if we could find a solution for this..... As would everyone with an upgraded final drive.

Which problem are your talking about? The auto trans showing the wrong gear with a different final drive?

The only thing this table controls is the gear display on the dash for manual cars. It doesn't have any impact on gear readout on automatic cars.

You can adjust the table by multiplying all of its cells by the percent change you induced by changing your final drive. Ex: If you went to 4.88 from stock 4.1, you increased the ratio by 19%. Another way of saying that is you're at 119% of stock. So take that percentage (1.19) and multiply it against the table. Your gears should read correctly now.

It doesn't make sense to me for that table to be for gear display. At pretty much any speed (leaving out extreme high or low) there are multiple gears you could be in for that speed. This table can't account for that by itself.

@makinen is correct, with the mfactory 4.67 final drive I get 1,2,3,3,4,5 on the display

The ECU also knows what your current RPM and speed are. It uses that table as part of the calculation to determine the current gear, not just by itself.