MSgpio.com read only forums (Jan.15,2018)

OK Lance I'll upload the code the first chance I get.


I should also point out that many FWD transmissions have a set of intermediate gears between the gear cluster and the pinion shaft, maybe add a line in the notes to point this out as its not obvious to new users and manuals often only list the primary and final drive ratios. Think of the these intermediate gears as like those on a traditional 'quick change' rear end (like a Halibrand).. you may want to consider adding this 'quick change' gear ratio to the Gear Ratio page.. although the code may be tricky.. but maybe RWD users may still use quick change rear ends?

In my case the ratio is 1.159:1 and so I simply incorporate it into actual gear ratios I input in TS... i.e my 2.7:1 first is inputted as 2.7x1.159 = 3.13:1

Addicted,

That's good to know. Is the VSS likely to be mounted between the intermediate gear and final drive on configurations of which you are aware? (If the VSS is before then it is on the output shaft, if it is after it is effectively on the wheel.)

If the VSS is not likely to be mounted between the intermediate and final drive gears, then it is probably easier to incorporate the intermediate gear ratio into the final drive ratio. In that case I can have a separate spot for the intermediate gear, and do all the calculations like this:

effective final ratio = final drive ratio * intermediate ratio

So it should be easy to add to the code. I will look into this.

Lance.

Obviously I cannot speak for ALL FWD transmissions, but I can say that other than mk1 Golf manual transmissions ALL that I have dealt with (Ford,VAG, Renault) have thier VSS sensor on the output from the trans, after the final drive. I suppose that makes a lot of sense for manufacturers as they don't have to calibrate speedos for different final drives..

Martin

Martin,

That's what I would have thought as well. I will put this in place in the code shortly and post it here to see what you think.

Lance.

Martin,

Here is some test code with the intermediate gear ratio parameter added under VSS Setup:
It appears to work on my bench. The number to enter is the ratio of the rpm of output shaft to the rpm of pinion. So for example if the gears were 2:1 and slowed the pinion down compared to the output shaft, then you would enter 2.000.

The default value is 1.000 (i.e. no intermediate gear).

Let me know if you don't think this implementation is right.

Lance.

Just a quick question Lance, I've upgraded to the latest 5099 code and my Can1VSShz has increased by a multiple of ~7.2

I need to investigate a little further (I only noticed in the evening when I was reviewing datalogs). Speeds v Engine RPM v Cgear are all still correct.

Example:
Datalog from December:

26mph @ 1400rpm in First gear = 25hz

39mph @ 2046pm in Second gear = 40hz

Datalog from yesterday

25mph @ 1365rpm in First gear = 180hz (25hz x 7.2)

39mph @ 2036rpm in Second gear = 286hz (40hz x 7.2)

Like I say, I'll investigate further this evening..

Curiously, in Neutral, wheels off ground, at idle (957rpm) I see 10mph and 72hz, again a ratio of 7.2.......

ddicted,

Yeah, the VSSHz is back-calculated from the speedo when using the CAN speedo, so it needs to take the adjustment factor into account. I obviously didn't get this right when I reworked those calculations!

Are you using the CAN speedo adjustment factor (i.e. not == 1.000)? This should be easy to sort out, but it would help I if had your msq to test with, so if you could post yours that would be great. If you happen to have a datalog, that might help too.

Lance.

CAN speedo? I don't follow you..

I'm in the office at the moment and my datalog and msq are on the PC at home, I'll post them when I get home in about 2 hours..

7.2 is one of those magic numbers in relation to things that rotate..

Addicted,

Are you getting your speedo value from the engine controller over the CANbus? That's what I call the CAN speedo (as opposed to using the VSS input circuit on VR1 directly).

I have had a look on my bench, and things appear correct here at my end with the default values (60 mph == 1584 Hz on the VSS regardless of the speedo adjustment factor).

However, I did have to fiddle with all the speedo calculations to put the CAN speedo adjustment in for MS3 users, so that's most likely where an error has crept in. But until I know the exact configuration you are using, it will be hard to narrow the error down further.

So post your MSQ/log when you get a chance and I'll have a look.

Lance.

Hi Lance,

Datalog and msq attached. My speedo is not CAN, I have the VSS input circuit VR1..