Feature Request - Tach Change..

ErnieJones · Post by **ErnieJones** » Wed Oct 29, 2014 1:55 am

Hi!

I ran into an interesting issue the other day with my new Microsquirt Module install. I'm running a single cylinder engine with sequential injection.

What I found was that my tach was incorrect by exactly half. ie, 10K was displaying as 5K.

I posted a question about it and some very bright people came in and said it was caused by the tach signal only being triggered once every 720 degrees...in other words, it was because I was using sequential injection. This made sense and these guys were pretty smart.

So I looked through Tuner Studio and I found a setting that cuts the tach output in half. This was cool to see because clearly it can be adjusted, by in this case I need to double the tach output.

My thinking is that if you can programmatically halve the tach output with a setting in TS maybe you can also add an option to double it without too much effort. This way, people who are running sequential, and find their tach is running at exactly 50% can fix it just by a setting in TS.

What do you think? Would that be hard to add? It would make my OE tach work perfectly and I can't help but think that others may run into this issue too.

ErnieJones · Post by **ErnieJones** » Wed Oct 29, 2014 2:11 am

Hi!

I ran into an interesting issue the other day with my new Microsquirt Module install. I'm running a single cylinder engine with sequential injection.

What I found was that my tach was incorrect by exactly half. ie, 10K was displaying as 5K.

I posted a question about it and some very bright people came in and said it was caused by the tach signal only being triggered once every 720 degrees...in other words, it was because I was using sequential injection. This made sense and these guys were pretty smart.

So I looked through Tuner Studio and I found a setting that cuts the tach output in half. This was cool to see because clearly it can be adjusted, by in this case I need to double the tach output.

My thinking is that if you can programmatically halve the tach output with a setting in TS maybe you can also add an option to double it without too much effort. This way, people who are running sequential, and find their tach is running at exactly 50% can fix it just by a setting in TS.

What do you think? Would that be hard to add? It would make my OE tach work perfectly and I can't help but think that others may run into this issue too.

slow_hemi6 · Post by **slow_hemi6** » Thu Oct 30, 2014 12:58 am

Halving or other divides are quite easy you just don't pass through every second pulse or block x out of y for whatever fraction. However doubling the output is much more complicated due to the fact the extra generated pulse needs to occur midway between two real pulses. So you have to measure the period between two real pulses and then output a signal at twice the frequency. But as a tach signal is constantly changing the ecu has to be performing this measure and double routine very often to get a nice gauge response.

LT401Vette · Post by **LT401Vette** » Thu Oct 30, 2014 7:41 am

You could add a new output channel to a custom.ini file:

Code: Select all

[OutputChannels]
    doubleRPM = { rpm * 2 }, "RPM"

Then assign the tachometer to use that OutputChannel.

ErnieJones · Post by **ErnieJones** » Thu Oct 30, 2014 2:14 pm

This is good news! I was hoping it would simple. Many thanks for your help on this!

I created a custom.ini file with the contents above and placed it in my projectscfg directory. It's saved as a .ini file and I used a conventional text editor (it is .ini NOT .txt)

If I go in and enable tach in Programmable On/Off Outputs and then look for doublerpm I don't see it.

I did a bit of searching and it appears that when you start a project it's supposed to load maincontroller.ini and then custom.ini Yet I don't see that option (doubleRPM)

Is there a trick to get it to see that new option?

LT401Vette · Post by **LT401Vette** » Thu Oct 30, 2014 3:26 pm

Nope, no trick... Please post the custom.ini you have.

ErnieJones · Post by **ErnieJones** » Thu Oct 30, 2014 3:29 pm

LT401Vette wrote:Nope, no trick... Please post the custom.ini you have.

OK, here it is...

slow_hemi6 · Post by **slow_hemi6** » Fri Oct 31, 2014 12:50 am

Phil do you realize that he is trying to double the speed of the ecu's tach out pin? Not just double the reading on the tuner studio dash screen......

LT401Vette · Post by **LT401Vette** » Fri Oct 31, 2014 6:46 am

slow_hemi6 wrote:Phil do you realize that he is trying to double the speed of the ecu's tach out pin? Not just double the reading on the tuner studio dash screen......

Nope, didn't catch that... That would be out of TS's control. That would be in the firmware.
I would 1st look at your settings to see why it is reading half speed.

ErnieJones · Post by **ErnieJones** » Fri Oct 31, 2014 9:35 am

LT401Vette wrote:
slow_hemi6 wrote:Phil do you realize that he is trying to double the speed of the ecu's tach out pin? Not just double the reading on the tuner studio dash screen......
Nope, didn't catch that... That would be out of TS's control. That would be in the firmware.
I would 1st look at your settings to see why it is reading half speed.

I believe it was a side-effect caused by choosing sequential injection....

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