Team-BHP - EGR system - What's it purpose & when does the EGR valve open/close?

Hi all. I own a Sumo Victa GX TCIC. its a real good machine and I am happy using the same. One thing I was trying to figure out and I need your help on this one. I read on various sites and understand that the EGR system should be off when engine is idling. i.e. egr valve must be closed. Was doing research on my victa and I found that the EGR valve is open when the engine is idling and goes off when the accelerator is pressed. In the manual it says EGR comes in on partial load and speed conditions. I could not figure out how the EGR V/V gets actuated in speed conditions. I want that the EGR Should only come in at speed conditions and should remain off while the engine is idling ( say when I am stuck in a traffic jam). How can I do this on the Sumo Victa. Wud be greatful if someone can advise.

Best regards
SuMo

In petrols excessive EGR can lead to misfires, not so in diesel.
In most engines it is not applied at full load(if done it will reduce power output), and at zero load(idle) so that there is no misfire and erratic idle(petrol).

So Having EGR open in partial load is correct. If it was a petrol engine it would be off in idling, but since its a diesel thats not really needed. There is a complex system of solenoids which manages the amount of exaust going in. At high load EGR off is correct, otherwise it would lead to drop in power when you are flooring the engine for power.

EGR Valves

Thanks so much for the reply. So as I understand , in idle the EGR on is OK. Now my first querry is, There is one so called potentiometer on the Throttle lever. As the accelerator is pressed this pot's lever gets pushed in. I removed the plug connecting to this pot. Checked voltage on the pins , it was 12 V DC. Connected the OHM meter to the pot's leads ( with supply plug removed) it was showing high resistance. then I pressed the POT lever slightly , with the OHM meter connected , and it was showing zero Ohms , i.e. short circuit. Connected back the plug. Is this a Simple switch or a potentiometer ? if it is a potentiometer then the resistance should gradually decrease from high to low unlike in switch when it jump from high to short circuit. Pls note that at High resistance of this POT the EGR valve of the Victa gets the Vaccum and at low ( or 0) resistance it is shut. Do u think my POT could be faulty or there is something else in the system ?

Quote:

Originally Posted by porsche_fan (Post 407390)

Almost all diesel engines conforming to E-3/BS-3 and above have EGR. It helps reduce the NOx emissions from the engine by re-circulating the exhaust from the engine to the inlet air. Too much of this however, can cause problems and the most common example of this is the 'black smoke' problem with the Safari DiCOR when it was launched.

+1 to tht. EGR in Diesel reduces the O2 content in the intake to reduce the formation of oxides of nitrogen or NOx. Cooled EGR works better. Increasing the % EGR would lead to more soot in the intake causing wear issues. EGR normally tends to lead to a slight drop in power, However the new age engines with EGR control maps are not affected.

Has anyone tried removing EGR from their Diesel engines? This is what Wiki has to say on this subject:

Quote:

EGR deletion

EGR deletion in diesel engines is considered justifiable by a wide range of people, including the environmentally conscious. Although deleting the EGR system results in increased NOx level hydrocarbon emissions, Particulates, Carbon monoxide and Carbon dioxide are drastically reduced. Furthermore, EGR deletion results in an increase in fuel economy as high as 25%. Exhaust gas recirculated back into the cylinders adds wear-inducing contaminants and causes an increase engine oil acidity, which can result in an inefficient, poorly running engine. The increased level of soot also creates the need for diesel particulate filters to prevent environmental contamination.

Source

I have been toying with this idea for a while now, but wanted to know if anyone with a CRDi mill has done this already, and what was the result - more interested if you have tried this on a Hyundai CRDi, as mine is a Getz CRDi :)

Quote:

Originally Posted by lalitk25 (Post 1811082)

hmmm seems interesting but what would happen to the peak temperature in combustion chamber for which this EGR was installed in first place?.....

EGR was not meant to help with the temperature, IMHO, and lowering of temperature is only a by-product. It was meant to reduce emission alone, and in fact some cars come with EGR cooling- where the recirculated exhaust is cooled and then let in the engine chamber.

Again, quoting from the Wikipedia:

Quote:

However, exhaust gas (largely carbon dioxide and water vapor) has a higher specific heat than air, and so it still serves to lower peak combustion temperatures. There are trade offs however. Adding EGR to a diesel reduces the specific heat ratio of the combustion gases in the power stroke. This reduces the amount of power that can be extracted by the piston. EGR also tends to reduce the amount of fuel burned in the power stroke. This is evident by the increase in particulate emissions that corresponds to an increase in EGR. Particulate matter (mainly carbon) that is not burned in the power stroke is wasted energy. Stricter regulations on particulate matter(PM) call for further emission controls to be introduced to compensate for the PM emissions introduced by EGR. The most common is particulate filters in the exhaust system that result in reduced fuel efficiency. Since EGR increases the amount of PM that must be dealt with and reduces the exhaust gas temperatures and available oxygen these filters need to function properly to burn off soot, automakers have had to consider injecting fuel and air directly into the exhaust system to keep these filters from plugging up.

So do we have anyone in Team BHP who can say "been there, done that"?!! ;)

Quote:

Originally Posted by ph03n!x (Post 1811339)

If you read article about EGR valves provided by tsk1979 then there it is clearly explained "It was discovered way back when, that high combustion chamber peak temperatures (the really short duration high temperatures near the end of the combustion process) caused oxygen and nitrogen to combine chemically and form these oxides of nitrogen mentioned above. " and to stop this reaction EGR intake was introduced so that peak temperatures are avoided and as a result formation of oxides can be avoided, thats why as stated by you

Quote:

Originally Posted by ph03n!x (Post 1811339)

and in fact some cars come with EGR cooling- where the recirculated exhaust is cooled and then let in the engine chamber.

is done to lower the temperature.

So lower temp. is not the by product, it is actually the core mechanism to lower emissions at the expense of power and economy.

Like someone said, EGR came into existance to meet Emission Norms, now EuroIII did not require a cooled EGR to meet the norms but in Euro IV you cannot meet it without a cooled EGR. The technology revolves around meeting Norms and has evolved accordingly.

If you remove the EGR you will get a SERVICE LIGHT due to sensors detecting higher emissions and loss of vaccum to the EGR.