Atkinson-to-Otto transitioning

Does anybody have information on the Atkinson operating parameters? When does it switch to Otto? In the Toyota videos, Sweets clearly states that you lose torque in Atkinson mode. He made it sound like Atkinson primarily operates during highway cruise speed (whcih is where everyone is having problems with the engine/tranny). He also mentioned the low-torque issue is solved by switching back to Otto cycle. But it seems like maybe this isn't happening. The tranny hunting appears to be caused by low torque - the engine can't maintain speed so it downshifts. But does it try switching to Otto before a downshift?

Just curious how the engine switches between Atkinson and Otto. How is it controlled? Does a big input on throttle bump it back to Otto?

Also does ECT lock it in Otto? That'd be ideal. If there was a way to limit the Atkinson engagement it'd be nice to play around with and see if performance improves.

 

far as I know ECT changes gear shift and throttle mapping.

 

But it doesn't lock it in Otto cycle mode?

 

Doesn't exactly roll of the tongue as

https://www.youtube.com/watch?v=cmBKHSZ1pcU

 

not that I am aware of.

 

I really wish there was an indicator light on the dash to show if it's in Atkinson or Otto mode.

 

I've been thinking about a thread that died a few months ago where a guy asked if there was a way to lock his engine into Otto cycle. I feel he got unfairly treated by some members who didn't understand or didn't appreciate why he was asking the question. This is a similar thread and I think worthy of discussion. If we could lock or engines into Otto cycle only, it seems like, at least in theory, we would a more powerful engine under all conditions. I really hope that more information is released about how our engines are operating and even more importantly, if there is a way to lock our engines into Otto cycle. Obviously, only Toyota Corporate would be able to do it at this time, but maybe over time if Toyota doesn't address the problem with engine/transmission issues, somebody may figure out a way. And while I'm dreaming, a way to lock into multiport injection. You guys do know that our engines have two injections systems, right? I'll gladly give up a couple of MPGs for a better performing engine.

Oh, and thanks for the tune Wolfttaco. Likely written well before any of us were born, and spelled differently, but a nice diversion into a different world.

 

ReB55 it's now known as Burlington Northern Santa Fe. When Burlington Northern and Santa Fe merged to become one in 1996 Solidifying one of the largest train mergers in the country. Judy Garland also sang the tune in "The Harvey Girls" 1946

 

I don't have any firsthand experience, but you should be able to tell which cycle it's running by monitoring any pressure or temperature sensor on the exhaust side using an OBDII bluetooth dongle coupled with the Torque app. Since the Atkinson cycle fully expands the power stroke, the exhaust pressure should be near ambient, and the temperature accordingly lower. When in Otto, the temp/pressure should jump.

 

I highly doubt there is anyway to control the cycles. The ECU controls it all and Toyota locks those.

 

I'd be willing to bet that Toyota right now is working on adding the Atkinson cycle capability to the 5.7 in the Tundra. This is their strategy for fuel economy to keep displacements higher in their engines and adding Atkinson as opposed to Ford (smaller engines and adding turbos.

 

Welcome to TW

Enjoy your stay

 

That would annoying having a light flash off and on

 

Or change the engine cover and make it a Miller Cycle.

 

I'd like to learn more about this too. Especially for Manual transmissions.
I thought I read somewhere that Otto kicks in around 3/3.5k RPM. But that could be completely wrong.

 

I believe cycle selection is mostly a function of throttle setting. Cruising on the highway, it's in Atkinson; floor it, and you get Otto.

 

Can you point me to documentation that explains if it actually switches between Atkinson and Otto cycles? In my casual reading I don't recall it every going into Otto mode.

 

It's a funny motor and I'm still getting used to it. When you're at idle and accelerating, it sounds like a small diesel (but not in a bad way). When you reach cruising speed, it turns Lexus-like.

 

It does do Otto. Watch the Mike Sweers videos on here. It's not a true Atkinson cycle, it just simulates the Atkinson cycle by altering the valve timing to leave the intake valve open for part of the compression stroke. Thus, ita easy to transition back to Otto by reverting valve timing back to normal.