Drive By Wire, or Electronic Throttle Control

[one finger john]

Since we are talking 'bout drive by wire, do any of the fuel injection manufacturers have a program that will drop injection pulses (either randomly or pre-planned) that will mirror the old Cadillac 8 6 4 firing order that can be used to aid fuel economy?

John

 

[Hotrod46]

Since we are talking 'bout drive by wire, do any of the fuel injection manufacturers have a program that will drop injection pulses (either randomly or pre-planned) that will mirror the old Cadillac 8 6 4 firing order that can be used to aid fuel economy?

That alone won't do it. The Displacement on Demand (DOD) schemes in use on modern cars manipulate the valves in the dead cylinders to eliminate the compression drag. Just cutting the fuel would probably increase fuel consumption. I think the original Caddy system did this too, but the technology wasn't durable enough.

The special DOD lifters used on the GM LS engines are supposedly very sensitive to excess oil pressure and will die if they get too much. The DOD LS engines have an extra oil pressure relief valve near the filter.

 

[Hotrod46]

Potvin, I know you're trying to do this without any processing, but computers do open up a lot of possibilities. Cruise is one, but if you had a wheel speed sensor on the front and rear wheels you could do a simple traction control scheme.

If the rear wheel speed was greater than the front, you could cut throttle until they matched. I know you wouldn't want something like that all the time, but in certain situations(like wet roads) it would be handy. TC is what has made it possible for manufacturers to sell the new modern super high HP muscle cars.

Just thinking out loud.

Mike

 

[PotvinGuy]

Potvin, I know you're trying to do this without any processing, but computers do open up a lot of possibilities. Cruise is one, but if you had a wheel speed sensor on the front and rear wheels you could do a simple traction control scheme.

If the rear wheel speed was greater than the front, you could cut throttle until they matched. I know you wouldn't want something like that all the time, but in certain situations(like wet roads) it would be handy. TC is what has made it possible for manufacturers to sell the new modern super high HP muscle cars.

Just thinking out loud.

Mike

Thanks for idea, Mike. I've built some complicated hard-wired logic for the military (they don't like software for several reasons) and am real comfortable with it. I'd like to play with the Aurdino, but don't have time for the learning curve right now. I plan to start with the basic logic (push the pedal and the throttle opens), then maybe add some fail-safes and fancy stuff if I don't kill myself first (I've been trying for years with limited success).

 

[PotvinGuy]

How do you guard against a malfunction is this type of system??? Could it go to 90% pulse width and lockup there?

The OEM's have been doing it for 20 years. They incorporate lots of safeguards, including comparing the butterfly position to the pedal position. If they don't match, the ECM will kill the throttle body motor, kill the EFI, kill the ignition, or even deploy a drag chute (I made that up). And the butterfly has a return spring, just like we do on our carb, to bring the engine to idle if power is lost to the throttle body motor and the ECM doesn't catch it.
I'm guessing that liability is the reason no SEMA company has done it. GM could weather a big lawsuit, even a bogus one, but Joe Bob's Speed Shop would be a goner. Lokar will sell you a sexy pedal to replace your cheesy factory pedal, but that's as far as they go. And no one makes a 4-bbl throttle body with ETC. All the EFI guys (Holley, FAST, MSD) have pretty 4-bbl throttle bodies in their kits, but no ETC.
It's interesting that electric power steering is now common, but they still keep the mechanical linkage so you can steer even if power is lost.

 

[Indycars]

If you have a rev limiter, then that could be set really low for testing purposes.

I guess you are planning then to do some of the same things as the OEMs?

 

[Hotrod46]

I've built some complicated hard-wired logic for the military (they don't like software for several reasons) and am real comfortable with it.

I've got to respect anyone that can design and build complex circuits from individual components. Everything is PLC based now.

I've had a little simple coding training and MIGHT be able to tinker something together with some processing power and a lot of trial and error. Wouldn't really know where to start with components.

I admit that I was surprised that the OEM's don't use steppers, but after the explanation it makes sense to use PWM with it's power off fail safe.

I'm subscribing to this one. Going to be interesting to keep up with the progress.

Mike

 

[PotvinGuy]

It's a real story, Mike. The military came to our company with a project needing an airborne unit that could comm with ground stations and exchange data. I was barely out of school and knew how gates worked, but this was way out of my league. But the boss said do it, so I read up on shift registers and other IC's, drew a flow chart to guide me, and it grew like a weed. We didn't have any real digital test equipment, so I built a box to generate pulses and read logic levels. Lotsa long nights, but the thing worked. Of course the govt cancelled the project before we ever got to fly it. But damn it was pretty.