Hybrid Engine Shut-Off at Highway Speeds?

Hello all, my first post (and first Toyota as well as Tundra).

Question about the TTV6 Hybrid. I get that the gas engine shuts off at low speeds for MPG savings; the hybrid battery is modest, but light pedal presses seems to keep the truck rolling on pure electric through 10-20MPH.

Yesterday, though, I was going about 68 MPH on the highway and let off the gas on a downhill(ish) portion for a second or two—the gas engine shut off. I thought gas was constantly engaged over a certain MPH? Can this really be good for the gas engine to be shutting off all the time, even on ultra-short foot depress/brief highway coasting?

Hoping to see if this is a normal feature, or potential glitch. My first hybrid, so I’m a bit paranoid as I learn the system.

Thanks all!

 

It’s normal. As more hybrids are being delivered this is being reported by all owners. If you’re on the highway and going downhill or don’t need the power, the gas engine will shut off and run on electric.

 

Welcome…and yes it’s normal so not to worry.

Enjoy the truck

 

Yep gas engine shuts off and while coasting the electric motors are charging the batteries.

 

Does the electric motors run while you are using cruise control at 70? Thanks in advance.

 

With cruise control, the gas seems to stay engaged the entire time at low RPM. Yesterday was just highway speeds, no cruise, downhill, and took foot off gas — engine shut off at near 70MPH and let the electric engine take over. Never saw that before.

But, other comments suggest this is normal. These new-age engines are insane. Can’t imagine it’s good for the gas engine to shut on/off so many times, but I trust Toyota engineers. If that’s by design, I’ll assume the best for longevity.

 

…same principle goes for that auto stop/start in most manufacturers vehicles these days (starters and everything that makes it work)…people love to hate them and they are supposed to save gas but time will tell.

My wife’s 2016 XC90 was my first ownership experience with it and 7 years later we haven’t had any issues (knock on wood) so the automotive engineers have figured a few things out.

 

Yes it's normal, and no it's not damaging to the motor to start stop all the time. They designed it this way. And if I'm not mistaken, the hybrid actually has two ways to start the vehicle, the traditional starter and the electric motor starter.

 

That's what it does. Doing what it supposed to do.

 

Not sure about other hybrids but Toyota hybrids don't have starter motors, they use the hybrid motor to start the engine which is much more powerful than a starter motor.

 

I'm pretty sure they've taken car of the turbos. My 2017 Fiat 1.4 circulates coolant through the turbo for a few minutes after shutdown. If Fiat figured it out, I'm sure Toyota is on it too. Hell, Fiat probably stole the idea from Toyota.

 

I have set cruise to 65mph on my work commute on I-40. I have 2 declines during the run, on those declines the truck shuts off and goes electric for 15 seconds or so and then restarts.

 

I’ll go with Toyota engineering on this one…

 

Well, yeah, you forgot to add the chick fila drive through time, the starbucks window, the carwash, and waiting on my wife in the grocery store time. Adds up baby.

 

The Tundra has a separate starter motor. I believe it is only used under certain conditions (extreme temps, etc.).

To the OP’s question, I think a lot of people see that the vehicle will cruise on the electric motor alone up to 18 mph with light throttle input and then it needs to switch to the gas engine. They’re missing the fact that the gas engine only stays on when vehicle load or electric load requires it. If you’re coasting downhill, at any speed, and not using large current draw for AC and lights and stuff, the engine (and electric motor) have no reason to provide energy to the vehicle, so the engine shuts off. It doesn’t mean that you’re moving on electricity only, like you can at speeds under 18, just that the vehicle has no need for power going to the wheels while coasting downhill.

 

I don't have a dog in this fight. However, prior to finding my '21 Pro, I had placed an order on a '22 F150 Tremor. Although my order had the "stop/start delete" as part of my build, it wasn't due to reliability or issues in long term wear/tear from that feature. I just can't stand having my engine shut off on me like that; drives me freakin' nuts!!!!

It was my understanding that Ford has had this feature (stop/start) for years now w/the ecoboost, and although they've seen other reliability issues, the stop/start didn't seem to be a contributing factor

I guess I'm just agreeing w/ @Retired...finally on this and saying I'd hope that all that was taken into account by Toyota during the engineering process and that '22 Hybrid owners will not have to sacrifice long term reliability for those types of 'features'.

 

The truck has an oil pump dude. How stupid do you think engineers are? Toyota has been making hybrid cars for over 20 years, and turbocharged cars for much longer than that. I have driven MANY Toyota hybrids and never had any issues whatsoever. The A/C stays on when the motor is off, too. Most taxis in my area are Toyota hybrids, and they all have outlasted the Crown Vics that they replaced. I can find you many of them with over half a million kilometres on the original drivetrain.

 

A lot of speculation in this thread. Obviously Toyota hybrids have existed for ages with this engine shutdown technology and there are many with over 200-300k miles. And the AC compressor on the hybrid is electric. It has a thick orange cable going into it.

 

You're flat out wrong, bud. The A/C compressor is electrically driven, and the electronic oil pumps are set to maintain the required amount of oil pressure. Modern turbochargers have technology to feed them coolant and oil, even when the engine is at 0 RPM. If a random guy on a forum is aware of the pitfalls and risks of a start-stop system in a car, then the engineers are aware of it too, and will address those issues.

 

For those that do not like the auto start/stop feature, there is a button located on the far left side of the dash, down low, that you can depress that will over ride the start/stop feature.

Thats the option I choose, and it works great

 

Unfortunately the linked website does not specifically address any differences in the hybrid version of the V35A-FTS. If members here who have iForceMax trucks aren’t losing AC when the main engine shuts off then I guess we take their word for it.

As for the other “problems” you are worried about I would point out a few things:

1.) You are operating under the assumption that Toyota has programmed the engine to shut off regardless of engine operating conditions leading up to triggering an auto stop/start event. Given that readings and data can be monitored on exhaust gas temperatures, recent boost levels, engine coolant temperatures, oil pressures, engine loads, inlet air temperatures, etc; are a whole host of information sources the ECU has to determine when and if to shut of the primary engine. If you have considered it as a potential problem maybe Toyota power train engineers have also accounted for this in programming.

2.) It seems like you might also be making an assumption that the iForceMax relies on a conventional starter motor to restart. It is my understanding that unless the temperatures are very very cold the motor/generator handles all starting duties. The hybrid battery doesn’t like extreme cold so it needs to warm up a bit. Hence a conventional 12V battery under the rear seats, and a normal starter for extreme cold starts.

Since it’s clutched into the same shaft as the crank on the V35A-FTS it’s probably possible that the gas engine is being spun prior to firing on an auto start. That would allow for building oil pressure pretty quickly before any fuel or ignition events.

3.) I think you’re worrying a bit excessively about oiling issues as if the engine is seeing repeated cold starts where oil has drained completely into the sump away from the valve train, and the engine is cold. In this instance we’re looking at a warmed up engine with recent oiling and all lubricated engine parts most likely still being covered in an acceptable film of warm engine oil.

4.) You might have overlooked the separate cooling system, complete with electric water pumps, of the turbos and intercooler. Particularly on the iForceMax coasting and regen braking down a hill at 70 MPH those turbos should be seeing plenty of cooling. With ample airflow through the intercooler system radiators, and no additional heat from hot combustion gasses dumping heat into the turbine side of a turbo on a shut down engine, the electrically circulated coolant should have no problems keeping temps in check.

 

Your link is for the non-hybrid motor, no Toyota hybrid has a belt driven A/C compressor. The non-hybrid motor has a few variations over the hybrid motor.

 

All AC compressors in all cars cycle constantly. They have an electrically actuated clutch mechanism that cycles the compressor off and on. Not sure what you’re on about with your anti-hybrid rant. Spreading misinformation isn’t helpful here. Come back when all these trucks have imploded and become paper weights after 100k miles and tell us all told you so. But I bet that’s not how it’s gonna go down.

 

My AC compressor cycles several times a minute in all my gas powered cars.
They obviously didn’t hit the mark with you for the new Sequoia. I think it looks A plus, but I’m a fan of simple and reliable myself. But imagine if we all dug our heels in when fuel injection came out. We’d still be choking our carbs and smelling like gas. Airbags, seatbelts, double wishbone suspension, modern stereo systems, lots of improvements have been made and turned out great long term. Maybe the first and second go round didn’t pan out, but persistence paid off and we have better cars for it.