Quick question: 2UZ-FE: Direct or Indirect Fuel Injection?

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Phat1842Many

Phat1842Many

10 Year
Joined
Mar 7, 2013
Threads
14
Messages
117
Location
Austin
I did a couple searches and I can't quite pin it down. According to wikipedia (see here) the 2UZFE has "MFI", which I gather is "mechanical fuel injection". (I thought that meant carbureted but I guess that's separate?)

I'm filling out an application for testing in France for conformity and it is asking if the engine gets fuel via direct or indirect injection.

I thinking this is too simple, but my brain is exploded from all the questions on this form.

Cheers!

Phat-
 
The 2UZ uses indirect injection. direct injection in gasloline engines is a new thing...

injectors are in the intake runners just before the intake valve.

MFI = multiport fuel injection.
 
Mfi or multi port injection. Meaning the injector sprays fuel in the intake port. It does not spray directly into the combustion chamber which is usually associated with direct injection.
 
Thank you both. That was very clear. One more question: Do we have an EGR valve? I don't see it on the emissions sticker in the engine compartment but I want to be sure.

Cheers!
 
OregonLC said:
It does? Don't think the LC 2UZ has one.
Click to expand...

Looking at the FSM, I don't see one. I was pretty sure I saw one when I was working on mine in the past, but must have been mistaken. I've never heard of an EGR fail on a 100, so either it's really good system or non-existent!
 
I installed headers and there is no EGR connection that I recall... EGR is old school I think.
 
AimCOtaco said:
I installed headers and there is no EGR connection that I recall... EGR is old school I think.
Click to expand...

Variable valve timing has eliminated much of the requirement for EGR. But when the LC 100 came out, an EGR was pretty standard, no? I wonder how Toyota got away without it on the pre-VVTi?
 
I don't know, now you've got me curious...
 
AimCOtaco said:
I don't know, now you've got me curious...
Click to expand...

What also has me curious is how this relates with the Air Injection in the 06-07. Back in the day, AI was used to remedy incomplete fuel combustion. By adding oxygen (air) the hot unburned fuel would continue to burn in the exhaust. This also created a hot exhaust stream. EGR, however, was used to remedy NOx by cooling the exhaust through introducing exhaust (that won't burn) back into the cylinder. Seems like the two are at odds with one another.

Curious to learn a) what makes the 2UZ low enough on NOx to not need EGR (on the non-VVTi rigs) and b) why AI was needed with the VVTi (06-07). Was the non-EGR because of an EPA vehicle classification perhaps? I seem to recall somewhere that the 100 was actually classified as a medium-duty vehicle?
 
Phat1842Many said:
Thank you both. That was very clear. One more question: Do we have an EGR valve? I don't see it on the emissions sticker in the engine compartment but I want to be sure.

Cheers!
Click to expand...
The 2UZ-FE does not have an EGR at least in the US-spec models. The later 06-07 units had secondary air injection to warm up the converters faster for a better performing cold start emissions. The thought behind having an EGR is a simple question, with many different potential answers only Toyota Emissions engineers can truly answer so I'll do my best being a prior Toyota engineer LOL.

Using an EGR can have a few different positive benefits. The most common benefit is a cheap way to mitigate a lean tune in a vehicle without producing excessive NOX emissions or having spark knock (aka detonation). The reason why I say this method is cheap, is manufacturers produce an ECU tune to fit within EPA guidelines that also will yield good mileage. The biggest problem with this, is you have multiple more moving parts which as we all know leads towards more component failures. This method is also considered a band-aid to poor cylinder head/combustion chamber design.

Toyota has gotten around the use of the EGR on multiple models through better ECU tuning, as well more stringent parameters for all of the sensors to operate in to avoid poor combustion behaviors. This also being more common in the SUV and truck line is another reason why our fuel mileage is worse than other brands, but the converters tend to last so much longer than average. With better ECU tuning and a better combustion, the cylinder head/cylinder block runs cooler and with a better fuel burn, that also works the converters less so your not sending excessive unburnt fuel down the exhaust pipe.

When Toyota develops an "Offroad" or "Truck" platform the focus tends to be on over-engineering for longevity rather than the most horsepower and fuel economy. A great example of a platform that has impressive horsepower and fuel economy would be the 3.6L Chevy V6. But with the numbers being so good Chevy also has many issues with this power plant like: Oil consumption/Timing Chain stretch/Excessive strain on cooling components.
 
You must log in or register to reply here.

Share this page

Back
Top Bottom