More progress on safety software around electronic throttle: rusEfi now supports using both sensors inside the electronic throttle. Both are converted to a throttle position, and double checked to make sure that their values are near one another. On a short drive today, the positions of the two sensors didn't differ by more than around 0.1%. Considering that the actual resolution we have is only around 0.03%, that's pretty good!
I see the project for ETB DBW started in 2014, what are the main hurdles still preventing feature and safety complete implementation?
I was actually looking for resources so that I can replace my non-bosch etb with a bosch unit but with a custom controller and thought the code and hardware existed out there or maybe some sample code, turns out that it was not as simple as that.
I thought it was not ready, as the in the video a few posts above you show how the throttle plate gets stuck and oscillates before going back to normal later on(something about feedforward).
As for the ECU, it's a tad bit more pricey than I would've liked. I am guessing it's in that aluminum casing to protect against EMI? Are they really a concern when near the ignition system?
And lastly in the video you just posted, what kind of calibration do these bosch throttle bodies need?
Re: electronic throttle body control ETB
Posted: Sat Nov 18, 2023 6:32 pm
by AndreyB
See ETB DBW feedforward and PID autotune demo
Re: electronic throttle body control ETB
Posted: Sun Nov 19, 2023 8:12 am
by dikidera
In what instances is feedforward and autotune required? How do they improve what is currently available in electronic_throttle.cpp?
Re: electronic throttle body control ETB
Posted: Thu Jan 18, 2024 7:22 am
by motomarzel
I have an idea, but would like to read more opinions to check whether it is viable...
As you know the engine without fuel injected and/or without ignition is just an air compressor. That is why we use it as a brake. But normally, under braking the throttle body is closed, which is restricting the air coming into the engine and thus reducing the pumping forces. In order to improve engine braking, in my opinion, considering that we are able to control the throttle body, it makes sense to wide open it in order to have higher pumping forces and thus engine braking power. That of course will require some additional sensors - brake pedal, clutch and gear engagement. Or maybe just additional switch to activate that "engine brake" mode...
it makes sense to wide open it in order to have higher pumping forces and thus engine braking power
Does not make sense to me. I was under the impression that opening throttle makes it EASIER to pump since air flow is less restricted. With throttle closed pump has to suck and that takes effort.
Re: electronic throttle body control ETB
Posted: Thu Jan 18, 2024 5:14 pm
by tmbryhn
Andrey is correct.
A simple experiment that verifies Andreys statement above: Disconnect fuel/ignition and crank the engine. The cranking RPM will increase if you open the throttle. That should tell you that the pumping losses, eg. breaking force is decreased as the manifold pressure approaches atmospheric.
Use the coasting table to modulate how much pumping loss you'd like during engine breaking/coasting.
Re: electronic throttle body control ETB
Posted: Fri Jan 19, 2024 2:33 pm
by motomarzel
Maybe you are both correct. It just sounds contra intuitive to me, because the suction volume (chamber) is much bigger compared to pressure (compression) one, as it includes the volume of the cylinder, together with the intake manifold and the valve intake path in the head.
I tough that this braking method is not used due to mechanical throttle bodies and the carburetors from the past.
However I don't have that much experience with gasoline engines behavior, since I have been mainly driving diesels, but I have had experienced the starting force needed to crank my lawn mower (4-stroke) with throttle open vs closed. The open throttle requires more force to pull the starting rope, therefore I tough that engine braking with open throttle might be more effective.
However, I might be wrong...
P.S. I have finally discovered a thread where the topic is widely discussed, in the end they have found that braking with closed throttle really in more effective but with very tiny margin - however it was good to discover... - https://forums.autosport.com/topic/89377-f1-engines-and-engine-braking/
Re: electronic throttle body control ETB
Posted: Fri Jan 19, 2024 10:09 pm
by tmbryhn
Your lawnmower is probably a 2-stroke. Might make all the differance...
