Tachometer tech

[Roman]

2 hours ago, zep said:

stuff

Hey, 

IF you run your tacho as an output from the ECU, then instead of allocating it as being just a tacho, you can make it a GP PWM table. 

Then you can output a frequency and/or pulsewidth that corresponds to each rpm point on a table, so you can get it 100% accurate even if the zero point of the needle of your swapped in unit doesnt line up.

You can do the same with a speedo too, I did this to both on my Carina because neither of them were accurate at various points on the gauges. 

[zep]

1 minute ago, Roman said:

Hey, 

IF you run your tacho as an output from the ECU, then instead of allocating it as being just a tacho, you can make it a GP PWM table. 

Then you can output a frequency and/or pulsewidth that corresponds to each rpm point on a table, so you can get it 100% accurate even if the zero point of the needle of your swapped in unit doesnt line up.

You can do the same with a speedo too, I did this to both on my Carina because neither of them were accurate at various points on the gauges. 

I will probably do this. But I know others who are still running points/etc that might like one, was hoping I could develop something for them too.

I guess I could try and use the speedo too. What did you do about the odometer for the speedo? The stock one is mechanical and I guess is needed for a WOF.

[Adoom]

2 minutes ago, Roman said:

Hey, 

IF you run your tacho as an output from the ECU, then instead of allocating it as being just a tacho, you can make it a GP PWM table. 

Then you can output a frequency and/or pulsewidth that corresponds to each rpm point on a table, so you can get it 100% accurate even if the zero point of the needle of your swapped in unit doesnt line up.

You can do the same with a speedo too, I did this to both on my Carina because neither of them were accurate at various points on the gauges. 

Thread hijack. Does that Carina speedo that you can control with the ECU live on its own circuit board, so that it could be relatively easily transplanted into an old smiths gauge? 

[Roman]

Yeah to had to swap in the guts from a later model speedo to make it work. Was from an st202 celica or something like that. The odo came with it, and I lost my trip meters.

The tacho worked just with the addition of a resistor, from memory.

[zep]

Ah yeah, that makes trying to swap a speedo circuit/unit into an older gauge face/cluster a bit harder, as you'd still have to find a way to drive the trip meters.

[zep]

Grabbed an EK cluster. Turns out the tacho is also an air core but has a microcontroller integrated on the circuit board. It still takes oldschool inputs but doesn't have the potentiometer that I believe the EG has. Back to pick a part again I guess!