Why is this turbo so anxious??

In very few miles my experience has been the same. Loves to hang low!

 

I respectfully challenge that assumption.

Valid for old school butterfly carburetor motors where throttle controls airflow, maybe not so much for direct/port injection motors where the throttle by wire indirectly controls fuel injection and other factors

 

Yes, I noticed similar when test driving 4th gen’s. Very refreshing vs my 2017

 

I agree with you here. And I think that’s why everyone was trying to point me to “dude it’s fine,” but we get that a LOT in this world and more often than not, people don’t have receipts to back up their claims.

Figured others with the MAX system would be able to chime in if they had any tips for this behavior. It is nice however that you provided some very good information and is appreciated. I’m always up for a challenge as well!

Ultimately it seems these engines are designed to operate this way. Keep gear longer, use boost and battery instead of shifting. Why? For comfort (according to Toyota). I need to drive in “sport” mode a little and see if that changes the dynamic similar to “tow” mode and report back. I much like watching the mpg climb over being a little “faster.”

 

There’s so much out there in terms of engineering and quite frankly too much going on under the hood. My brother works at an auto plant as has no idea why they make the engines do A, B or C. You are absolutely correct. I’m sure it’s doing a lot and accounting for the pressure.

Coming from someone who drove manuals for 20 years, the same 1990 sedan (5spd Mt) for 9 years and then moved to automatic turbos, it’s been interesting. Never are these cars doing what I think (and thought I knew) they should be doing. Downshift? Naw we’ll just hold the gear. Upshift? No, we’ll hold the engine at red line for you no problem… A little boost? No you get ALL the boost.

Also my previous cars as the boost builds you feel a “slingshot” effect as the boost spools up and propels you faster forward. This seems like the turbo is just there instead of the other two cylinders… not knocking Toyota… (but 15psi at 1,700 rpm might be knocking the engine)

I love the truck by the way.

 

Pressure and mass flow rate are two different things.

In a traditional carbureted, naturally aspirated engine when you step on the “gas” pedal you are mostly just opening the throttle plate (possibly more than one).

When the pistons move down on the intake stroke, much more air is pulled into the cylinder and more fuel is pulled in with it. This means more power is produced.

The key to making more power is to put more air into the cylinder so that you are able to burn more fuel.

The throttle is used to control the air flow into the cylinders.

Gasoline turbochargerd engines still have throttles.

At low loads, the throttle will be mostly closed so that little air is admitted into the engine. The fact that the throttle is mostly closed means that there will be relatively little exhaust produced to spin the turbine which spins the compressor.

This means that the compressor is not pumping a lot of air. Since the throttle is mostly closed, the pressure on the intake side of the throttle can increase. But the throttle is in control of the amount of air admitted.

The boost gauge is misnamed. Boost is actually best understood as the excess mass flow rate of air entering the engine over a naturally aspirated engine. The boost gauge you are reading isn’t giving you mass flow rate. It’s merely giving you pressure.

When you press on the “gas” pedal, the computer tells the throttle to open and fuel injectors to add more fuel. Because your turbocharged engine is modern and not some unsophisticated 1980’s lagging nightmare, that pressure you are worried about as being excessive boost isn’t really excessive. It’s just a bit of priming waiting for the throttle open.

Once that throttle opens, the air enters the intake manifold and ultimately into the cylinders.

If you are on the beach and a Tsunami is coming or on a mountain top awakening into a volcano, you will likely push the pedal to wide open while screaming.

With wide open throttle, the air freely enters the engine and becomes exhaust which spools the turbo up.

Unlike before when you were tooling about keeping the throttle barely cracked open, this time the compressor is making real mass flow rate.

During WW2, aircraft engines had rated power. They had another rating called war emergency power. War emergency power was used when not using it meant imminent death. You could use war emergency power for a short time before war emergency power might kill the engine. Hopefully, the mess requiring war emergency power was quickly cured by war emergency power before war emergency power melted the things required to produce war emergency power.

I really hope the Tacoma has war emergency power which can be activated by satellite and knowing your location, elevation and proximity to incoming tsunamis.

 

Welcome to the future gramps, we've got twin scroll, direct injection, high compression gas engines that are basically one bad tank of fuel away from becoming diesels

There's a reason why the big turbo builds all make power up high in the RPMs. Port injection, stout RB/JZ/K20 bottom end or whatever, huge fuck off injectors + high RPM = tons of fuel being sprayed = cooler cylinder temps = less chance of detonation

I wouldn't want the Tacomas T24A-FTS in a sports car, it would be one of the most boring sports cars ever. You'd be shifting at 3K RPM before it falls on its face. As a truck motor its great though, probably the best motor the Tacoma has ever had, (about as close as it gets to a diesel aside from Mazdas Skyactiv Turbos).

We had a B48 powered Mini Cooper S and it made peak torque around 1700RPM too, was pretty boring as far as gas engines go.

I like my EJ255 much better Although my favorite is the B16A in my GFs EG6.

 

I see. So in this case with throttle barely cracked open, can you paint why do you think the gauge goes full at the low RPM? I understand because of pressure, but why do we need all the pressure at such low RPM? Unless the answer of course is just because.

And this is something that my elaboration misses. The exhaust is pushing the turbo so more air, more exhaust, it’s really hand in hand correct? It’s not like the turbo is randomly blasting air into the engine and not able to do anything with it. This makes total sense.

You got me cracking up on this one. Pretty much what I was trying to do, use the turbo like a reserve for war emergency power.

 

Hey I’m not thaaaat old lol and explains the need for 91

all you had to say! Makes perfect sense now.

I’m loving the truck, MAX is interesting and taking some time to get used to since I previously was able to disable stop/start. The sales guy told me there’s no starter on these.

I don’t think there’s a better engineering than a good 35yr old b16a that still screams. Talk about 5,000 rpms at 80mph and about 12 mpg!

 

Also OG big turbo builds had lower base comp, like 8.5:1 or 9:1 , another layer of protection against knock and detonation

 

That's still more evidence than your speculation that the truck's programming is wrong, which is just a lengthy description of why you don't like it.

I doubt Toyota engineers just drew up a truck and crossed their fingers, and we got what we got. Seems much more likely that your truck performs as designed, which lends credence to "it's supposed to do that". This version of the T24a doesn't even run high enough compression to require 91 octane.

I'm with you on LSPI, and lugging an engine in the boundary lubrication range of the Stribeck curve. My truck is a manual, which means user error can create boundary conditions; but yours is a hydraulic pump with solenoids gears and clutch packs - all monitored by sensors and controlled by a computer that was designed and programmed by engineers.

Makers have been exploring small displacement, high output, turbocharged, direct injection engines for over 20 years. Mini's turbo engine introduced in 07. Ford's 1.0 EcoBoost started a whole family of engines. Other manufacturers jumped on board. The 2.0T used by VW/Audi, AMG's 2.0, Honda's 1.5, Toyota's 3cyl in the GR Corolla, etc... Some brands had problems with piston fractures, caused by LSPI, now mitigated by oil formulation and revised engine design. There's a reason ILSAC GF-6A is the minimum for these engines - because it addresses LSPI.

So yeah, "it's supposed to do that" is a valid summary.

 

Then you're thinking about it wrong. You want to contain the pressure you intend to create.

The analogy is a firearm, which is a 1-stroke cylinder 'engine'. If you add more powder, you create more chamber pressure. The breech must withstand that pressure. If you forcibly add more fuel air mix, you create more cylinder pressure. The cylinder (and related components) must withstand that pressure, and the rotating assembly must withstand the resulting force.

 

Get out there and lay that Mother down.

 

I don't know how one would think the gauge is somehow fake. Fairly often I can hear the turbocharger itself, and the gauge rises with it. Typical of turbochargers forever, climbs and hard work build the boost more. Unlike older drivetrains there's automation to cut the boost too.

What I mean by the automation is I've driven the 4th generation Tacoma on some same climbs, mountain passes or towing where I drove turbocharged semi tractors. The modern automobile doesn't require your eyes on the exhaust pyrometer, temperatures and the driver adjust manually.

I would not overthink this stuff. Toyota's only made a few hundred million vehicles, and for turbocharged pickups the experience goes back to the 1980s. It would be front page news and often if they were even remotely insufficient or a broad problem.

 

For what it's worth.

I have a 2007 Acura RDX - AWD, 2.3 liter turbo 4 cylinder. Rated at 240hp / 260tq. There's also a little turbo gauge from the factory.

It also shows some level of boost even at 20-30% throttle. I think it's just a characteristic of turbocharged small displacement engines.

 

All great feedback!

 

Because that's the only way to make 317 lb/ft of torque at 1700 RPM's with a 2.4 liter 4 cylinder. These engines are designed and tuned for low end torque and fuel economy.

 

Your thread is almost 5 pages in and you still haven't been able to "show the receipts" that there is any damage being done inside your engine

All you've demonstrated so far is a nostalgia about how engines "used to be"