major_bvv wrote:In your post you have only one true thing EGR was invented only for ecological reasons. But EGR works directly FFECTS engine normal work. In addition -the EGR ALSO closes no matter what rpm you are when hitting the full throttle. DID YOU KNOW THAT- OR NOW I'm mega turbo,hyper,giga cool.

zok wrote:...at low/middle torque demands...

When on WOT, EGR is fully closed, and has no inpact on combustion or performance.

Booyaka?

major_bvv wrote:Why you have EGR COOLER than?

It is a heat exchanger, not cooler. It is used to heat up the engine quicker - specially for providing enough heat for the passengers more quickly (same function as electric coolant heaters) and to lower emmissions and fuel consumption after cold start-up. And to make exhaust gasses more dense - to induct more gas mass without using larger engine components. Not every car uses EGR heat exchanger.

major_bvv wrote:exhaust gases (250-350 degrees celsius depending on model and engine type) are cooler than the air through the intercooler ( 20-35) ?

If EGR gasses temperature is the only problem, then why exhaust gasses that pass through the EGR never go through intercooler? They'd been cooled down much more efficiently, and car production would be cheaper with less parts.

major_bvv wrote:Give me science.

Because NOx forms primarily when a mixture of nitrogen and oxygen is subjected to high temperature, the lower combustion chamber temperatures caused by EGR reduces the amount of NOx the combustion generates (though at some loss of engine efficiency).

- source

another one...

blah blah blah...


Less oxygen - lower temps. Simple as that.

I agree with you Zok.

EGT temperatures rise as there is more oxygen present with egr off as the burn is better therefore more heat produced into exhaust gas temperatures (EGT).

The timing is now more advanced with egr off as with egr on the timing is retarded (slower burn) and then with the egr gases missing as the egr is blocked off the timing becomes more advanced and does need retarding a little to compensate for the more oxygen content.

It sounds like pinking on a petrol car with egr off.

I agree with you too Zok, i am a educated mechanic and the EGR valve is made for one purpose only..

It recycles the exhaust gasses to reduce nox emission, this i done by reducing the combustion temperature.
Besides that we can all agree that it isn't good for your intake because it gets black and filthy :)

The nox emission happends when your engine temperature reaches about 1000 degress celcius.. :)

SO Zok couldn't explain it better than you and you nearly quoted every book i have on the subject.. :)

What about the timing issues though if the erg is turned off? Nobody has commented on this yet? Please somebody comment. :)

Anybody turned erg off and noticed the difference in the engine noise on light throttle? Anyone hear that it sounds like pinking?

Anyone have a solution to this?

Zaccyboy, maybe you should try to record a video where the sound is clear.. !! :) That would help me alot in explaining what i think i could be.. :)

But on some EGR valves the head of the valve is a bit loose, maybe that is whats making the sound.. :)
But when you turn if off how do you turn it off, there are different ways to do it..

If you have turned it off by changing values so that it's closed forever you cant dismount the EGR.. But if you do it right and cut of the communication between the engine ECU and the EGR valve.. :)

Then it would be possible for you to take off the egr valve and close it off with a piece of metal and some "sealant"

Ps. English is not my first language, so if something is hard to understand feel free to send me a pm.. :)

Thanks supernielsen,

I deleted an egr on my previous car a Honda civic 2.2 icdti. I deleted it in software and blanked with a blanking plate.

I had the same noise as I have now it is the timing, it is too advanced and needs to be retarded on light throttle only where egr occurs or happens. At full throttle it is disabled anyhow. Do you know the winols address for my citroen xsara picasso 1.6 hdi?

Cheers Ian

Im sorry im only mechanic and im on this forum to learn about all the things recarding chip tuning myself.. So i cant help you with the adresses.. However im just trying to help where i can.. :)

But from a mechanics point of view i cant seem to get what that noise is.. If it is a never car and it have that clear mechanical noise there is a "knock" sensor that should adjust the "timing" according to the noise so it should get reducted..

But as it dont i think maybe there is something wrong with one of your maps, it sound like the fuel gets ignited to soon in that area.. Maybe you can change that in the duration map (depending on how good my understanding is of the things i have read already)

But i will leave that to someone else, im just trying to help :)

Thanks Supernielson,

I am looking at the soi maps at moment and asking for help with positive and negative figures.

I need to find out what maps are used at what ECT temps.

I will keep people posted.

Thanks for every bodies help.

About EGR valve, I think removing EGR also afects turbo pressure... When it's in good working order, mainly in low RPM, EGR valve also removes pressure in turbo turbine side (exhaust), so once you block que exhaust recirculation you will increase the pressure. In higher RPM EGR is closed so no change.
I think by blocking EGR valve recirculation you get more power on lower RPM.

There are two ways of blocking EGR valve recirculation, physically with sphere or metal plate, or my software changing ECU to comand EGR to be closed. The problem, I think, about software is that the EGR motor will work on stress.

Zaccyboy wrote:I need to find out what maps are used at what ECT temps.

Try to find a selector map.

I'm not sure about Bosch, at Delphi it is usually just before a set of maps for one parameter - like (just an example) - first there is one small FRP selector map and just after it, there are 6 FRP maps...