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it sounds like the Road Speed Sensor Constant Pulses/KM scalar in the VS xdf's if that's any help.

i've been working on the $A6 xdf update recently and i have VSS Ratio as offset 2022.

looks like default of the tune im looking at is 41.50 and the scalar has a range of 0 to 64.

having said that im not sure how much it needs to change for a certain ratio change.

Is the car a manual or auto delcowizzid?

I think that one is to do with gear ratio's which is why it fixes it but not the dash as the other setting is the pulses per km from the sensor, which i should fix both? Would they both reference the PPK?

looks like possibly at 3818 16bit no calc in CNPD for PPK

What you think?

There are two different logic paths, one for manual and one for auto and both have a ppk type value (pulse/rev for auto at 0x201D and ppk for manual at 0x3818). This calculates the trans output speed, for the auto there is then code and a conversion factor (0x2022) to determine the actual speed in MPH and KPH (it calcs MPH and then multiplys by 1.61) while the manual gets MPH directly and just does the KPH conversion.

And for an extra bit of info, the MPH/KPH calc routine calcs two final figures using different input values. One is for the PCM to operate with and one for ALDL (which goes to the dash). Having two final values is common in the PCM as the input value can be defaulted if there is a failure while the ALDL value is generally the true value which helps fault finding (except in this case for a VSS failure it goes to 255KPH, not sure how the dash handles this though).

yeh i was just about to say it looks like rpm/kph as auto would need it for shift point calculating and also determining rpm slip.

You can also adjust each gear 1-5 381B-F like the vss ratio

Yep there is a ratio calc so the PCM can determine which gear its in, even with a manual gbox

This calc should work, obviously not super accurate? to what's in the stock tune, apparently some tyre manufacturers have specs for Rev/Mile in US, nothing here on tyres i have looked up.

Stock Tyres
205/65R15

(205 x .65)/25.4 = 5.25 inch Tyre Diameter

20168 / ((5.25 x 2) + 15) Works out Overall Tyre Diameter & Results Rev/Mile

(791 x 3.08)/60 = 40.60 Approx RPM/VSS Ratio

its 304 auto meant to be having a nother sesh on it tomorrow night

well thought i would let everyone know how this is going with using the injector offset table for tuning.

after half a dozen logs most of the area where the car is in most often are pretty close blms and as you can see its carved out a nice little adjustment in the injector offset table below.



now i am by no means claiming that adjusting this table is the right way to go, but its definately working for us at the moment!

oh and for reference, back on page one of this thread is the original post with the stock table in it.