Can the OBDII port give info to control an electric motor?

[Ryland]

The other day I saw the start of a home built plug in hybrid truck and it looked like it was well on it's way to being put on the road, the only thing that I did not like was that it was going to have two throttles!
So my question is focused on the OBDII port of a Ford Ranger pickup truck, because that is the vehicle that was being converted and my parents have the same vehicle and if I can make something that works I think they would let me make their truck a plug in hybrid, or at least my mom asked when I was going to start that kind of project with their truck

My two lines of thought are to either go with a simple and crude speed controller, basically a vacuum diaphragm that would control a mechanical throttle pot box for the electric motor, this would be the same idea and driving with a vacuum gauge only the electric motor would be kicking in under low vacuum.

The other idea is to use the OBDII port and have something like an Arduino monitor engine load, although I suspect that is more or less looking at vacuum as well? but with that it would be all electronic so tweaking could be done with programming instead of with springs and hoses and if done well should, in theory be more reliable.

[jakobnev]

Maybe it has a TPS with a voltage signal?

[Ryland]

Originally Posted by jakobnev

Maybe it has a TPS with a voltage signal?

Yes, it does and adding sensors on is not an issue, but the engine already has the full range of sensors needed and they all feed in to the computer with a nice OBDII plug that allows my scan gauge to read that info, so why not use that plug to talk right to the speed controller, that is if it works, right?

It sounds tho, like the CAN-bus bar that the OBDII plug is taping in to can have a lag time because of slow refresh rates and if that is the case then my idea might not work, but if the refresh rate is quick enough then it should work just fine.

[Ryland]

I've been poking around a bit and asking a lot of people a lot of dumb questions, along with reading a bit about the Arduino micro controllers.
There appears to be two options that I've found for a "shield" (a piece of hardware/circuit board that plugs in to the Arduino to expand what it can do) that connects up to the OBDII port and gives useful information to the Arduino, so from the looks of it decoding the OBDII port is a hard ware issue not a soft ware issue, it's also a problem that sounds like it has already been thought about.
Sigalabs | Vehicle OBD2 Shield with STN1110 IC

Is the shield that looks like it's going to be more useful as it sounds like it self recognizes the vehicle it's plugged in to.

2nd issue that I was not sure about but checked today was the TPS (throttle position sensor) and if the OBDII port would get a reading from it if the engine was not running, my reason for wanting to know this is if you are driving a plug in hybrid and only making a short trip you don't need the gas engine to be running but you still want to use the accelerator pedal and TPS to control the electric motor and thus drive the vehicle, as it turns out the TPS gives the computer and thus the OBDII plug a reading even when the gasoline engine is not running.

[Daox]

Why not just tap into the TPS sensor and be done with it? Most controllers like to use a POT signal anyways.

[Ryland]

Because I also want it to base electric motor speed controller throttle input off engine load when the engine is running, but when the engine is not running the motor speed controller just listens to the TPS.

[dcb]

so tap the map sensor,
Reading a MAP sensor

or rpm and tps

use your obd tool to figure out/verify the lod formula from map