Back on my electronic governor

David G

Well-known Member
I built an electronic governor a couple years ago for my MH44 EFI using a late model throttle body. It was a prototype, with some issues, so I never installed it. It used an Arduino micro controller. The two main issues it had were analog resolution (1 out of 255) and the throttle plate was spring closed with a weak spring.

I have ordered a four channel analog to digital converter (1 out of 65535) resolution. I will use two of these channels to look at the throttle lever and two to look at throttle plate position. The reason for two channels each is that allows me to cross check the positions.

I need to find a two channel higher resolution analog out (PWM) converter for the throttle plate. One output will control the throttle plate and the second output will go back to the ECM to emulate the throttle position sensor. I will use a plus/minus bridge circuit so I can drive the throttle open and closed while using the spring as an emergency closed, this should give me much faster close response.

My concern was that the lower resolution will not adequately represent the mechanical governor.
 
Two thoughts, A resolver type pulse generator is one idea that would allow locational data. especially if it were geared to the throttle shaft at aa 50 to 1 ratio to provide high pulse count through a little less than 90 degrees of rotation. The second is a 10 dollar throttle position sensor from a 2001 Subaru outback. (not from the dealer) these are ~90 degree devices and very modest in physical size. They are variable resistor based. Jim
 
Jim,

You are spot on, I plan to use a standard Delco TPS for both throttle position and for throttle lever. The Arduino will get two inputs from both, one for position and one for validation. I can get plenty of resolution using the potentiometers, no need for encoders and parts are available via auto parts store.
 
Thanks for the sourcing information.

The MFI would be a welcome addition to my EFI, I can change the input from the MAP to MFI and get rid of MAP sensor. It is much more accurate/responsive to determine flow that way. The pickup sensor is the one I use on my crankshaft for position, it works very well and handles run out nicely.
 
I have two options, one is put a servo on the linkage that goes to my home made throttle body, the other is replace the throttle body with one I have that is drive by wire that has built in PWM motor. I do not know yet which is better option, but appreciate the questions, so please keep them coming.
 
Update:

My EFI ECM has a tach output, I plan to use that as speed input on governor. This signal is a square wave between 0-12V, so I will need to condition it.

The ADC, analog - digital converters are coming from China, will be 2-6 weeks, glad not in hurry. These are 16 bit, so will provide a lot of resolution.

I am still not sure on the PWM pulse width modulation driver for the throttle. I still want to go with an external converter so I can get better resolution.

I think I will use existing throttle body, that way it can be adapted to any engine, with or without drive by wire. I think a hobbyist servo will work fine for this, I can mount it and intercept the throttle rod from the existing governor.

Thanks for joining me.
 

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