Passat Coding changes

[Rocket36]

Yeah I knew about the remote close... Might just have to live with that.

[nivek]

Now I just need to drive down to Geelong and go through the speed checks on the freeway to see how accurate the CAN bus speed is...

Wouldn't a GPS unit provide you with a more accurate reading?

[Pana]

Wouldn't a GPS unit provide you with a more accurate reading?

Don't have one (apart from the RNS in the car) and dont have easy access to one.

[R36 Dreamer]

How loud is your chirp Dreamer?

Extremely quiet. Much quieter than I expected.

Definitely registers with my brain though - one chirp locked, two chirps unlocked.

[passatpout]

Don't have one (apart from the RNS in the car) and dont have easy access to one.

I've compared mine with my GPS, and went through 2 of the speed checks.. in both cases cruise was set on 105km/h, the GPS was showing 99km/h, the first speed check showed 104km/h, and the second 97km/h...

Whereabouts in Melbourne are you Pana?

[R36 Dreamer]

I've compared mine with my GPS, and went through 2 of the speed checks.. in both cases cruise was set on 105km/h, the GPS was showing 99km/h, the first speed check showed 104km/h, and the second 97km/h...

Whereabouts in Melbourne are you Pana?

At a single steady speed I believe GPS will be the most accurate, given it needs to measure speed to calculate time to destination etc.

What I found interesting is that if I am on the highway at a steady (GPS indicated) 110km/h and I reset the trip computer to zero out the Average speed reading, when the av speed comes back up it is the same as the GPS reading.

This leads me to believe the car is measuring speed correctly, but the speedo does not correlate with the car - if that makes sense.

[Swallowtail]

It does make sense, and that is because that avg speed function is dictated by the CAN bus speed I believe. Maverick's post on his website about altering speedos mentions this I think.

[Pana]

I've compared mine with my GPS, and went through 2 of the speed checks.. in both cases cruise was set on 105km/h, the GPS was showing 99km/h, the first speed check showed 104km/h, and the second 97km/h...

Whereabouts in Melbourne are you Pana?

South east - which speed checks did you go through passatpout - the hume hwy ones or the Geelong freeway ones?

[passatpout]

South east - which speed checks did you go through passatpout - the hume hwy ones or the Geelong freeway ones?

I think it was the Hume. Certainly a freeway with 2 of them on the same route, even my wife commented on how different the readings were - both were on clear road without any other traffic around.

Despite the fact there's one on the Calder near my place, I never drive on that section of the road..

[Pana]

Despite the fact there's one on the Calder near my place, I never drive on that section of the road..

is that after the thunderdome coz I was there a couple of weeks ago and didnt see one on the way....

[passatpout]

is that after the thunderdome coz I was there a couple of weeks ago and didnt see one on the way....

It's southbound, at the Bulla-Diggers Rest Road bridge.. was taped up and not in use last time I saw, but as I said, I very rarely use that section of the road.

[RobBentley]

ooh - nice info here.

I have an older copy of VagCom I have always used for my Passat W8, but it doesn't "speak" to the R36. I'm angling for a new CAN capable copy of VCDS from my other half for Christmas!!

[logger]

I've made a few coding changes using VCDS to my R36:

4. Made the speedo more accurate - now reads 105 at 100kmh instead of 108...

Just keep in mind that changing the impulse number to adjust the speedo also effects the Odometer but I suppose that is not big deal for most of us.

[Swallowtail]

Just keep in mind that changing the impulse number to adjust the speedo also effects the Odometer but I suppose that is not big deal for most of us.

Mav's site indicates otherwise, and I have read some people saying it does and some saying it doesn't.

Changing the impulse number doesn't change the CAN BUS speed, only the indicated speed. Why would they use a known (and deliberately set) wrong speed for the odometer? From me reading, the odometer is driven by the CAN BUS speed, so should not be affected by changing the impulse number...

Just my 2c, and I could obviously be entirely wrong, but it seems logical to me.

[logger]

Mav's site indicates otherwise, and I have read some people saying it does and some saying it doesn't.

If his site does say that then I believe it is probably incorrect. There is some other stuff there about the MFD speed warning indicating CAN bus speed which is demonstrably not the case with my car. I think the developers of VCDS Vag-Com, Ross Tech, can generally be relied upon to know how these things work, and I quote...

"There is no known way to change the relationship between the speedo and the MFI and odometer via diagnostics. Changes to the Distance Impulse Number should affect all of these equally." Uwe Ross Oct 2009.

Changing the impulse number doesn't change the CAN BUS speed, only the indicated speed. Why would they use a known (and deliberately set) wrong speed for the odometer?

I have no idea and it does not make a lot of sense but I would not discount what the Ross Tech fellas have to say.

But having said this, the change to your ODO will probably only be small and easy enough to live with. For time being I have chosen to leave that setting alone in my car.