Some details of the 2AZ-FE engine

On Tue, 15 Jul 2008 23:34:01 -0700 (PDT), Built_Well
<Built_Well_Toyota@m> wrote:

>Nate Nagel wrote:
>> Built_Well wrote:
>> > C. E. White wrote:
>> >
>> >> EdV wrote:
>> >>
>> >>> Is the 2AZ-FE considered a direct injectin engine?
>> >>
>> >>No
>> >
>> > =============
>> >
>> > The 2AZ-FE is a direct injection engine. It does not
>> > use a mechanical distributor, and the engine does
>> > use a crankshaft sensor and a camshaft sensor, among
>> > other things.
>>
>> "direct injection" typically refers to a very high pressure fuel
>> injection system that injects fuel directly into the combustion chamber
>> rather than into the intake runner or a throttle body.
>>
>> What you are describing is a "distributorless ignition."
>>
>> nate
>============================================
>
>Very good information. I enjoyed reading it, and you're
>right that the Camry does not inject fuel into the combustion
>chamber but into the "antechamber" in the cylinder head that
>comes just before the valve. That's what the manual's diagram
>seems to show anyway.
>
>But the 2AZ-FE /is/ a Direct Injection System. Here's a quote
>from the Camry's service and repair manual on Page EG-57:

No, it's not.
Direct injection is just now starting to be used in some European
cars. They're need for fuel efficiency is a lot higher.
>
>"A DIS (Direct Ignition System) has been adopted. The DIS improves
>the ignition timing accuracy, reduces high-voltage loss, and
>enhances the overall reliability of the ignition system by
>eliminating the distributor. The DIS in this engine is an
>independent ignition system which has one ignition coil (with
>igniter) for each cylinder."

Direct ignition is pretty much common on any car these days.

On Wed, 16 Jul 2008 09:43:13 -0700 (PDT), EdV <systmengr@m>
wrote:

>On Jul 15, 11:57 pm, johngd...@m wrote:
>> Hee hee hee. 2AZFE "an advanced powerplant?" that's a good one.
>> Checkout the Audi FSI 2.0T for an advanced design with a flat torque
>> curve from 2000-5000 RPMs.
>>
>IIRC, The flat torque is because of the CVT transmission design and
>not the engine. I could be wrong.
>.

A transmission has nothing to do with torque output of an engine.
A CVT is able to keep the rpms at max torque at all times while
accelerating.

RT wrote:
> On Wed, 16 Jul 2008 09:43:13 -0700 (PDT), EdV <systmengr@m>
> wrote:
>
>> On Jul 15, 11:57 pm, johngd...@m wrote:
>>> Hee hee hee. 2AZFE "an advanced powerplant?" that's a good one.
>>> Checkout the Audi FSI 2.0T for an advanced design with a flat torque
>>> curve from 2000-5000 RPMs.
>>>
>> IIRC, The flat torque is because of the CVT transmission design and
>> not the engine. I could be wrong.
>> .
>
> A transmission has nothing to do with torque output of an engine.
> A CVT is able to keep the rpms at max torque at all times while
> accelerating.
Max HP speed will give best acceleration.

On Jul 18, 11:05 am, "C. E. White" <cewhi...@remove>
wrote:
There is an injector in the combustion chamber
> instead of in the intake tract before the intake valves. Air is
> admitted into the combustion chamber by the valves. Fuel is injected
> directly into the combustion chamber, instead of being mixed with the
> air in the intake tract before the intake valves.

Ahh, so the intake valves is just for the AIR and the injector for the
FUEL. no pre-mixing involved. The mixing occurs directly inside the
combustion chamber. The fuel is pressurized and not the air like in a
turbo setup. Thanks!

Dyno wrote:

> Actually, the reason to go to mechanical lash is not for high speed
> valvetrain control but rather to reduce engine friction. The hydraulic
> lash adjusters exert a significant amount of force on the cam base
> circle, increasing mechanical friction. This IS both measureable and
> does contribute to fuel savings. If you examine the base circle of the
> came you can even see the lobe is narrower and flairs out to a wider
> surface (Ford Zetec).

That would be a lot more palatable explanation if not for two factors:

1) Lash adjusters (unlike hydraulic lifters) are generally located at
the valve-stem end of the follower. They're about the diameter of a
valve stem, not a lifter. Therefore, the plunger inside them is about
the diameter of a valve stem, not order-of 5/8 inch like a lifter.
Taking the oil pressure and multiplying it by the surface area of the
lash adjuster plunger produces a TINY number. When lift begins the
valves in the lash adjuster close and the entrained oil is
incompressible so they don't collapse, but the BASE CIRCLE pressure is
solely due to engine oil pressure multiplied by plunger area, and is
miniscule.

2) With roller followers cam followers, adding base circle pressure
doesn't increase friction much at all. That's one big reason they're
used- far far lower friction than flat lifters from base circle all the
way to full lift. And of course they can follow a lobe profile with a
much sharper ramp rate so that you can get long duration without
excessive overlap.

>
> With modern oils and their additive packages, the need for frequent lash
> adjustment is very rare. Most will make it thought the mandatory 100k
> emissions durability requirements with no adjustment.

No argument there, but I still think eliminating auto lash adjusters is
more cost-driven than engineering-driven. And I don't even disagree that
its a good idea to go ahead and save that money IF the engine can run
200k miles without opening the overhead, as we've come to expect from
cars with hydro lifters or hydro lash adjusters.

Leftie wrote:

>
> There are two problems with hydraulic lifters: they are more
> expensive to build and, more to the point for us, they tend to fail long
> before the rest of the engine. Who wants to have to spend $1k on new
> lifters on a car with 150k miles on it?

They FAIL before the rest of the engine? Hardly. Ask any mechanic how
many hydraulic lifters or lash adjusters he's had to replace because the
lifter or adjuster ITSELF was a root cause of a problem in the last 10
years and I'll bet you can count the average answer on 1 hand, and if
you probe further you'll find that those were typically in badly
neglected sludged-up engines.

Steve wrote:
> Leftie wrote:
>
>>
>> There are two problems with hydraulic lifters: they are more
>> expensive to build and, more to the point for us, they tend to fail long
>> before the rest of the engine. Who wants to have to spend $1k on new
>> lifters on a car with 150k miles on it?
>
>
> They FAIL before the rest of the engine? Hardly. Ask any mechanic how
> many hydraulic lifters or lash adjusters he's had to replace because the
> lifter or adjuster ITSELF was a root cause of a problem in the last 10
> years and I'll bet you can count the average answer on 1 hand, and if
> you probe further you'll find that those were typically in badly
> neglected sludged-up engines.

My engines were not "badly neglected". The motorcycle was given full
synthetic oil. The two Mazda engines may have had poorly designed oil
passages, but I've also heard from other people abut lifters failing.
Think of all the "stuck lifter" stories out there, and you may realize
that it isn't just bad maintainance causing it to happen.

>How may car owners ever use the automatic transmission dip stick?
>

All of them with half a brain.

How often do you actually add ENGINE oil? I never need to between
changes, but I still CHECK it weekly. Same with the transmission fluid.
The whole idea of maintenance is to CATCH a potential problem before it
becomes costly. Eliminating the transmission dipstick pretty much
guarantees a low-fluid failure will ultimately destroy the transmission,
be it at 10,000 miles or 200,000 miles.