Internal EGR

tephra · Nov 1, 2009, 10:11 PM

Hi Guys,

Someone recently asked me how the EvoX does EGR - well I found a fairly nice article that explains it:

http://www.motor.com/article.asp?article_ID=1506

It's for another manufacturer but I bet it would be the same on the X.

I wonder how our tuned MIVEC maps play a role here?

ie if we are already pushing the cam timings quite close, will the "Internal EGR" cause knock or any other bad things?

Cheers
D.

H Jensen · Nov 2, 2009, 01:11 AM

Well, from what I remember from my Emissions classes and what not. This shouldn’t cause knock or any other bad things besides a performance loss, because you adding inert gasses into the combustion chamber. So this is good for slowing down the burn rate and getting better fuel economy because your using less air and fuel to fill the cylinder and burn. This causes the combustion chamber to be cooled because it’s not using its full potential of Air/Fuel.

As for adjusting the Cam timing and MIVEC timing your actually changing the "internal EGR" function because when you change the valve overlap and timing you’re going to affect how this iEGR functions. For example you take your stock cam timing and then you adjust you exhaust cam and advance it so it seats at say TDC you will have eliminated the iEGR, or you can adjust the Intake Cam so it doesn’t open until the exhaust valve seats, or whatever you decide. So it’s easy to eliminate the function or make it work for you. You could in theory increase fuel economy by leaving the exhaust valve open longer to allow the iEGR to function longer allowing for less need of air/fuel mixture. HP and TQ will suffer.

I'm sure there is someone that can explain all this stuff a lot better, I wish I was back home so I could look this all up in my Notes and Texts. But that’s the downfall of being in Afghanistan.

Weapon X · Nov 4, 2009, 03:54 PM

That was a great read, but let me get this straight; it has no external valve or actuator it just basically lets the exhaust gas into the combustion chamber by cam phasing? thats it? thats great. recirculating it back into the intake manifold causes a mess in the intake tract and on the valves. so my other question is, how does the ECU know that its working properly? if it is an emissions related system, it most certainly has some way to check itself to make sure its working efficiently. in fact i think its a federal law. so if you can effectively bypass it by using aftermarket cams, i would imagine there would be some sort of CEL associated with it.

Clipse3GT · Nov 4, 2009, 04:13 PM

Well the EGR maps look like this currently... so what you are saying there will be a performance benefit by changing these to 14.7? I am not sure when the car interpolates or switches between map 1 and 2...

Also changing the EGR timing to all 0 in the table would get rid of the EGR... ?

tephra · Nov 4, 2009, 04:41 PM

Weapon X:

AFAIK the iEGR system doesn't suck exhaust back into the intake tract, but back into the cylinder.

so if you look in your intake manifold it should be very clean.

ie using fuels like BP ultimate probably wont make much difference - as the cleaning agent in them doesn't ever hit the intake tract (manifold or valves)

thoughts?

^ is Evap different to EGR?

H Jensen · Nov 5, 2009, 12:49 AM

Quote:

Originally Posted by tephra

^ is Evap different to EGR?

Yes, The EVAP is designed to keep blow by emissions from leaving the crank case and venting into atmosphere, so they use the whole vacuum lines in your basic models to suck out the crank case fumes and put it back into your Intake to be burned. This is the results of CA emissions, and it turns out to be a pritty nice deal for performance and safty.

the EGR is designed to "cool" cylinder combustion tempretures to prevent the forming of NOX.

tephra · Nov 5, 2009, 01:02 AM

yeah thats what I thought.

not sure what those Evap maps are for above

if we can leave the Evap to another thread that would be great

Clipse3GT · Nov 5, 2009, 09:34 AM

Quote:

Originally Posted by tephra

yeah thats what I thought.

not sure what those Evap maps are for above

if we can leave the Evap to another thread that would be great

So the EGR map just adds that much timing depending on load and rpm. So if you would make the EGR map alll 0's it should not hurt anything but get rid of the EGR. Not sure if it would bump performance.

Would it have any effect on gas mileage if you would make the section from 2500-4000rpm and up to 80 load for cruising and increase that section with timing. I wonder if it would help out fuel economy a bit.

tephra · Nov 5, 2009, 03:38 PM

no its a bit more complicated.

the timing is added only when EGR is active.

so once the ECU decides "ahh lets do some EGR", it will phase the cam shafts (to get exhaust back in the cylidner) AND apply the EGR ignition advance (otherwise you will loose power, from the slow burning mix)

tephra · Nov 5, 2009, 03:39 PM

I might see if we can "log" when the ECU decideds to do its EGR thing

acamus · Nov 5, 2009, 10:42 PM

EGR is opening according to EGR Duty table, so there is not much magic here.

Clipse3GT · Nov 5, 2009, 10:45 PM

I found that my car felt smoother with the the EGR table set to 0 and the evap table 1 set all to 14.7 . Didn't notice any ill effects...

mrfred · Nov 8, 2009, 02:44 PM

tephra, do the stock MIVEC maps look like they are setup for the scenario described in that article, or do you think there is a subroutine that rotates the exhaust cam phasing under cruise conditions to enable EGR?

H Jensen · Nov 9, 2009, 01:12 AM

My bet is that there is a seprate duty table that causes the exhaust cam phasing. ie: it has to meet certan requirments like closed loop, RPM, Load. stuff like that before it activates.

TTP Engineering · Nov 14, 2009, 09:19 PM

Quote:

Originally Posted by tephra

Hi Guys,

Someone recently asked me how the EvoX does EGR - well I found a fairly nice article that explains it:

http://www.motor.com/article.asp?article_ID=1506

It's for another manufacturer but I bet it would be the same on the X.

I wonder how our tuned MIVEC maps play a role here?

ie if we are already pushing the cam timings quite close, will the "Internal EGR" cause knock or any other bad things?

Cheers
D.

Yes Dave I was us discussing this subject with you.

We are using Kelford 214-B cams and have seen an EGR code come up with stock and 214-A MIVEC programming used on these cams so I think the car is expecting adjustments to these maps to keep the ecu happy with the more aggressive cams.