Many of you guys who've done your installation on cold air intake probably noticed this already. The 2008 Fit Owner's manual (US version) on page 252 says there's an EGR system attached. Also, I tried doing research and found this link.

A Little Automotive Tech Trivia - Popular Mechanics

But there's a couple of things I'm trying to figure out. Is there a certain RPM where the EGR works the most efficiently? If so, can I configure the fit to run on pure EGR to save lots of gas and go very very slow?

I suspect that EGR system might be the reason why some fits are getting more MPG than other fits since, since it purposely runs a lean fuel mixture with exhust gas in the cylinders. This results in using less gas over all, but less Horse Power, am I correct?

 

I'm pretty sure it sounds like a constant.
it doesnt sound like there is any specific rpm where the EGR is best implemented.
and usually better combustion means less gas, same if not more hp?
A CAI, SRI, or chamber intake would only better the combustion process, probably a minimal benefit to the EGR if any.

ps. this article is dated jan of 2006. looks like all fits since our USDM 1st gen are using the EGR. mpg all depends on the person's driving and his mods :3

 

The EGR (Exhaust Gas Re-circulation)system on the Jazz/Fit (like all modern cars) simply takes burnt exhaust gasses and re-introduces them into the combustion chamber to be re-burnt again for emissions reduction. The system on the Jazz/Fit has passages cast into the head and the HOT exhaust gasses raise head temperatures again for more complete fuel burning.

The system is an always on system that depends on readings from engine sensors and the converter to determine how much gas is re-circulated controlled by the ECU.

Trying to introduce more expended gasses will result in an extremely lean condition which is not good. Trying to actually run any vehicle on Exhaust gasses only will NOT WORK as they have been through the combustion process once already and there is not enough fuel left unburnt to be converted into power.

 

Maybe it's different on the Fit, but ever EGR I have worked on, ports exhaust gas back to the intake (that will in time make it to the combustion chamber but not direct) via a modulated valve, not the combustion chamber.

 

The exhaust gasses are not actually "reburned". They are reintroduced because they are lean in unburned oxygen. This results in a cooler fire in the cylinder, which yields a lower level on NOX (oxides of nitrogen) emissions. Only about 5% of the exhaust gas is reintroduced.

 

Yea you are wrong it IS DIFFERENT on the Jazz/Fit. The system used on the Jazz/Fit (the vehicle we are discussing on a Jazz/Fit forum) has PASSAGES CAST INTO THE HEAD that go from the exhaust side with a small hole in the exhaust port IN THE HEAD. Next through the head to the EGR valve housing then into PASSAGES IN THE HEAD that exit out a small hole in the intake port OF THE HEAD right outside the combustion camber. No involvement of the intake. From the exhaust port right into the combustion chamber INTERNALLY TO THE HEAD ONLY. Try looking into the ports if and when you ever work on the Jazz/Fit.

And the gasses are re-burnt how can they not be when they are directed into the combustion chamber and there are SOME unburnt combustible particles remaining.

 

WOW are you wrong or did not read what I wrote. No EGR ports the gas back in the combustion chamber is what I said and that is correct. You used the word combustion chamber and I was calling you out on that mistake.

The chamber is on the piston side of the valves on any head.

Intake is on the TB side of the intake valve and that includes the head runner and intake runner.

The intake and exhaust valves determine the combustion chamber location.

The combustion gas is ported back to the intake, at the intake runner and before that valve just like everyone I have ever seen.

 

The port is right outside the combustion chamber and there is no where else the gasses can go other than the combustion chamber.

 

Lol. Someone needs to take a picture while working on the Fit to settle this argument. But basically, I think Honda engineerers really thought outside of the box for this one. I'm an engine noob so I'm still trying to figure out the whole picture here. But it can't really hurt to learn a thing or two.

 

Yep agreed, outside the combustion chamber as I had said AND inside the INTAKE Port

 

This is what I said in the first post:

"Next through the head to the EGR valve housing then into PASSAGES IN THE HEAD that exit out a small hole in the intake port OF THE HEAD right outside the combustion camber"

 

No this is what you said....

get it right when you come after me

 

"Yea you are wrong it IS DIFFERENT on the Jazz/Fit. The system used on the Jazz/Fit (the vehicle we are discussing on a Jazz/Fit forum) has PASSAGES CAST INTO THE HEAD that go from the exhaust side with a small hole in the exhaust port IN THE HEAD. Next through the head to the EGR valve housing then into PASSAGES IN THE HEAD that exit out a small hole in the intake port OF THE HEAD right outside the combustion camber. No involvement of the intake. From the exhaust port right into the combustion chamber INTERNALLY TO THE HEAD ONLY. Try looking into the ports if and when you ever work on the Jazz/Fit."


There it is in black and white the whole post number six read it for yourself.

In the post you are quoting I never said how or what route they take. They get to the combustion chamber and they are re-introduced to the combustion chamber no matter what route they take to get there which I didn't mention at all until post #6

 

#6 post means nothing.
#3 post was the one you made the mistake and
#4 was when I enlightened you. They are the two that have relevance.

I fully expected you to back peddle after my original post #3

 

There is no mistake on post 3 I didn't reference as to how they got back to the combustion chamber only that they did. And post 6 just explained how they get there. No back peddling here.

 

"Maybe it's different on the Fit, but ever EGR I have worked on, ports exhaust gas back to the intake (that will in time make it to the combustion chamber but not direct) via a modulated valve, not the combustion chamber."

Above was my 1st post and you're next words took great exception to them saying I was wrong. Now you say it's correct you just failed to mention that "re-introduces them into the combustion chamber " now means into the intake port, as I had said from the start.

Your argument is circular and confused at best.

 

..... ....

 

It may be confusing for you but it is correct. And you didn't say intake port you simply said intake if we are going to get precise and re-introduced into the combustion chamber is correct but they are re-introduced via the hole in the intake port not the INTAKE which connotes the whole intake tract.

 

I'm glad I was able enhance your understanding of the combustion chambers location relative to the intake valve and the intake system. I'm sure this was a good learning experience for you. I suspect there will be more opportunities in that area so I'll be watching.

 

Ha what a laugh.... as it. I'm glad I could enhance your understanding of the Jazz/Fit EGR system it's DIFFERENT than all the other cars you have alleged to have worked on.