Gas saving mode at 25mph

yes, that's right.

 

Thank you

 

I'm not worried about fuel savings at 25mph... But I can't wait until they release an upgrade that nets serious fuel savings at 75 mph!

Until then, I'm going to enjoy burning up dead dinosaurs!

 

I will try to reproduce this today in my ‘18.

Fuel: it has been stated that if you are not applying the throttle, there is no gas being delivered to the combustion chambers.
If this is true, how does the vehicle maintain an idle?

And why is there engine (combustion) noise when I turn the key, and let my truck idle?

 

It has been clearly stated that the fuel is shut off during DECELERATION WHILE IN GEAR AT MEDIUM/HIGH RPM.
Hence it is called “Deceleration fuel cut off”.
Nothing to do with fuel injection at idle.

 

@ViktorG, I’m sorry some people have rock like heads, that said do you know if during fuel cut if the ecu also kills ignition? I have no use for this information as wether the truck does or not, it doesn’t effect me or the way I’ll use my truck. But my head tends to be more like a sponge and always wants more information.

 

It is hard to tell if the ignition is turned off since there are no obvious markers or indicators to tell you if the spark plugs are firing.
I would think they probably leave it on, one less algorithm to write into the ECM.

 

That explains it.

 

Dunno why they'd shut off the biribiris. Heck most all lawn mowers use wasted spark ignition that fires every crank rotation

 

curious if for example the ignition is turned off also, would that be like cylinder deactivation? or cyl deactivation is when the piston stops moving all together ?
I've heard about cyl deact. but don't know if it involves mechanical movement or just fuel & ignition.

 

Subscribed

 

Cylinder deactivation would be fuel cut to the deactivated cylinders during light/moderate load cruise condition (instead of on deceleration only).
Some manufacturers will also keep the valves on the deactivated cylinders closed to reduce pumping losses.
So, for example you have a V8, but under light load it would only run on 4 cylinders.
There is no way to stop the mechanical motion of the piston (well, not practically anyways).

 

Viktor,

It seems like you know your stuff. I know it has been talked about, but I find it very hard to believe fuel is being cut to cylinders on deaf elevation. If it is, it is for probably .003 of a second. If we could magically put a camera on the fuel injectors, I doubt we would see them shut off.

No matter what type of vehicle it is, even a lawn lower or an actual car, if you take away fuel you know it!

Under today's very high pressure direct injection, if you cut fuel you would hear and feel it immediately.

Toyota engines rely on the lubrication from the fuel to keep heat down and reliability high like Toyota is?

All this seems very interesting before and have never seen this in any other Toyota thread on here.

 

If you are decelerating down a very long hill in gear, say coming down from a mountain pass, the injectors can be shut off for minutes at a time, not a fraction of a second.

You don’t need a camera on the injector, just hook up a multimeter to it and you will see it is not getting supplied with voltage during deceleration fuel cut.

A lawn mower is different from a car in that if the fuel to it is cut off, there is nothing to keep the engine from stopping. In the case of a car, the wheels rolling down the road keep the engine rotating.

Tundras do not use high pressure direct injection, just good old port injection at 43 PSI. Regardless, direct injection vehicles are programmed to shut off fuel under mid/high RPM deceleration just the same.

The Tundra engine does not use fuel for lubrication because gasoline has no lubricating properties. (Diesel Fuel on the other hand IS a lubricant for the injection pump and injectors). Gasoline does cool the injectors on a gas truck, and it does cool the cylinder under peak temperatures experienced during wide open throttle (this is why most engines are setup to run rich at WOT). However that cooling is obviously unnecessary when the injectors are turned off and combustion is not happening.

 

Your motor is still pumping air, it plays your exhaust like an organ. I wouldn't say its the same sound, it gets much deeper on deceleration because the air passing through is moving slower, its much softer than the sound of cylinders firing.

 

This. The sound you hear from your exhaust, it ain't combustion. The valves are closed when combustion happens. That sound isn't stored in the cylinders and released when the valves open. Your exhaust note is the high pressure air being released from the cylinder colliding with the low pressure air in your exhaust. Even with no combustion taking place the engine is still an air pump and physics still apply.

 

Will adding aux cooler keep the engine combuating going downhill?

 

No. Not sure why you want it to, there is no need for the motor to burn gas while it is not doing work.

 

I still did not make it to the dealer. Clunk is still happening. Wishing it would just go away.

Been trying to drive and remember to keep my foot on the gas, but for some reason I keep lifting it off.

Around here we have a lot of roads with a double yellow line down the middle and a 25mph speed limit. Think any road with a double yellow should have a 30mph or higher speed limit. Else why not cut through the developments, speed limit is the same. But if I do 25mph down those roads I would worry about getting myself shot. Definitely see a lot of crazy driving and hand gestures if I actually do the speed limit. If keep it at 30 people behind me are civil. But in the developments I do keep it under 25.

But I was wondering if Toyota reduced the speed at which no gas is delivered thru the injectors. I do not remember my 2015 doing engine breaking at 25-30 mph when I simply removed my foot from the gas. Shouldn't I have to put my foot on the brake for the truck to use engine braking?

 

Thank you gents for the information. It appears, once again, I was talking out my ass. Appreciate the explanations and education.

 

I have had that issue and I’m on my 4th tundra. The transmission clunks when you press gas from coasting.
When truck is brand new the clunking is like rubber to rubber. As it gets older it feels worse.
I took one of my trucks with 20k miles to the dealer. We drove around with the head tech and he could hear it. We tested a brand truck immediately and it the clunk was there albeit not as harsh.

 

I complained to the dealer about the clunk. They say they all do it now, not sure what year it started but my 2015 4.6 did not have this issue. I asked about a software update to make it stop and they said they had none.

Until then I have learned to drive without taking my foot all the way off the gas. Has a small area near the top where the computer recognizes 'foot on gas' but no throttle is being applied. Only take my foot off the gas when ready to brake.
Also found that using S3 mode works as well, and can put your foot on and off the gas at will and does not clunk.

Think I will call them once a month asking if they have a software update.

 

There was a TSB in the past for shifting. Do not know what years, but a download of new software for the transmission. Maybe someone with more knowledge can link it or find it?

 

my 2013, 2018 and now 2020 have those clunks. There is stretch of road in my neighborhood that has a dip . As I approach the dip I would slow down and as press gas to start the up hill it would clunk. Almost always at the same spot. Every time

 

Drive it like you stole it and this will no longer be an issue.

 

ViktorG,

Do you happen to know if the dealer is able to adjust the ECM? I have a 2021 sequoia and experience similar symptoms as a few others on here

 

I have had this clunk since truck was new. Now got 83k on it. Seems like rear end play. In gears. But i thinks it's normal.

 

Any time I am not cruising I use "S" mode. I don't think It has ever clunked in this mode.

 

No clunks in "S"mode while driving in my truck.

Did OP ever trade in for a golf cart?