Throttle position sensor and ECU

[scarr999]

Hi All,

I am trying to make a remote that can rev my engine. I tested the principle by finding the ECU inputs from the throttle position sensor and just injecting (adding) a voltage to it. The engine revved OK.

I then made an arduino with I2C DAC, when I connect the output of the DAC to the ECU input and try to rev the engine usng the vehicles manual throttle it does not respond!  I disconnect the arduino and it works again. I assume the DAC is holding the input low preventing the normal throttle working,  I'm looking for advice if adding an open collector transistor to the DAC output would work?

voltages are low 0-1.3v DC

Thanks

Steve

[ifrythings]

I’m not sure what DAC your using but there mite be a power down mode in the DAC that will disconnect the output amplifier from the pin, this would allow the throttle pedal to work again. On a mcp4725 DAC, page 20 explains how this works.

[Renate]

You're connecting two outputs together and they're fighting. Ok, you might be able to use an output enable on your DAC, but the TPS is enabled all the time. Depending on how it's made, the idle position may almost be a short to ground.

One way would be with an analog multiplexor, but are you sure that you want to do this? Cruising in the fast lane and the engine cuts out completely? In downtown traffic and the throttle red lines?

[SmallCog]

I'm surprised its as simple as injecting voltage - When I looked into making an idle-up for my car it had some fancy hall effect encoder arrangement so you're lucky!

You haven't said what the purpose is, but given you said remote I'm assuming its not for use whilst you're driving?

In that case if you've got the Arduino working without the pedal, and the pedal obviously works without the Arduino, then have the Arduino disconnect the pedal when it's putting the revs up and disconnect itself when it's not.

Whatever you do be bloody careful, I've had the displeasure of driving a vehicle with the throttle jammed open.

[langwadt]

add a diode in series with the dac output (you'll need to increase the DAC output by ~0.7V). Then manual throttle will work normally, DAC voltage can only add to that