Disabling EGR

[dieselman]

Nox is reduced as a result of reducing the free oxygen, not the gas cooling the intake air. The recirculated gas is a lot hotter than the intake air so tends to warm the charge gasses.

 

[stevesey]

Nox is reduced as a result of reducing the free oxygen, not the gas cooling the intake air. The recirculated gas is a lot hotter than the intake air so tends to warm the charge gasses.

That's what I used to think, but I read something the other day - can't find it now. I think it was along the lines that less O2, means the mixture isn't as week, so combustion isn't as hot and as a result NOx is lowered further still as the NOx reaction works best at the higher temps (although this was stated as a secondary effect in the reduction of NOx the basic reduction in O2 being the primary one).

But my TDDI does have a engine coolant/exhaust gas heat exchanger before the EGR to reduce the temps - not sure if this is there to actively reduce temps or just stop the combustion temps increasing above normal (if you see what I mean).

 

[Alex Crow]

EGR reduces *peak* combustion temp to reduce NOx production, but overall the exhaust gas produced is higher temp (due to half the intake being hot exhaust gas).

 

[HERBIEMERCMAN]

on work i have done on gas fired combustion chambers if you recirculate the burned products of combustion, you reduce the vitiated products temperature due to the free radicals not being fully released due to lack of oxygen and NOX levels increase. SO if you are bleeding off exhaust gasses and then receiving a reduced temperature from the combustion taking place in the cylinders, then the modifed exhaust gas temp will reduce accordingly. we used to refer to this as the "lambent flame mode", a yellow low temperature flame that was lacking oxygen. herbiemercman.

 

[oigle]

They can't do that for two reasons, firstly they use the standard Bosch ECU and second it's a mandatory requirement to monitor EGR.


Full load EGT is the same as it was, low load is cooler, and I could see the water temperature gauge fluctuate as a result. I wrapped the exhaust manifold to compensate for this so have seen a maximum temp of 820C on a high speed drag up a hill with passengers.

As I've mentioned previously, pre Euro3 regulation there was no EGR.

I am rather stunned by the temps you mentioned here.
My experience with pyrometers in comp cars many ears ago had petrol powered, high boost motors (28psi) getting close to 1000°C in competition, at which the turbos were absolute cherries. Turbo diesels, by contrast, with 15psi under heavy constant load, rarely exceeded 550°C. This was always the accepted reason for turbos very rarely failing on diesels compared to petrol powered cars. The use of fresh, high flashpoint oils was considered mandatory with petrol power but not for diesel. Your figure of 820°C goes completely against that old theory. By chance, you didn't mean °F ??

 

[dieselman]

Your figure of 820°C goes completely against that old theory. By chance, you didn't mean °F ??

Definitely centigrade. Torbodiesels are happy up to about 800c and some petrols can be up to 1200c...then it's meltdown.

I've only seen that temperature once and I blame the fat occupants causing excess load..

 

[stevesey]

And was that after you lagged the manifold?

 

[dieselman]

Yes it was.

 

[oigle]

Yes it was.

So where has it got to without the lagging?

 

[snispo]

2t oil to my full tank

i add 200cc's of basic 2t oil to my full tank as i know this modifies the valency of the diesel fuel, ( increases the free radicals) allowing more complete combustion, pluss the increase in fuel pump and inj, valve gear lubrication etc.......

Hi. Can you please explain what 2t oil is? “I add 200cc's of basic 2t oil to my full tank” thank you

 

[turbopete]

i add 200cc's of basic 2t oil to my full tank as i know this modifies the valency of the diesel fuel, ( increases the free radicals) allowing more complete combustion, pluss the increase in fuel pump and inj, valve gear lubrication etc.......

Hi. Can you please explain what 2t oil is? “I add 200cc's of basic 2t oil to my full tank” thank you

its 2 stroke oil

 

[turbopete]

Hi all - haven't been around for a while, but I've recently moved over to satan's fuel - and manufacturer - as I'm now driving a focus TDDI (deliberately went for the TDDI to avoid DMF and common rail issues).

I have been considering blanking the EGR - but in doing some research, there is a very definite school of thought that the EGR operation at part load helps to cool the turbo (it's designed to cool the combustion so less NOx is produced - a side effect is that it cools the turbo - especially at the very lean part load mixture you get in a diesel). Supporters of this viewpoint quote the failure issues with Renault TD engines where (unusually) the EGR would stick closed (not open, like most do) - so owners wouldn't know and would drive for a long time like this (unlike the stuck open case, where the cloud of smoke behind you prompts you to do something).

DM - would be interested in your view on this - especially as you have an EGT fitted. Did you notice an increase in part load EGTs when you blocked the EGR? (I assume it's fitted before the turbo?) Also how do your part load EGTs compare to full load EGTs (a lot of people try to apply petrol engine logic top the argument and that doesn't work for a diesel).

At present I'm swinging towards leaving it alone - partially because it's a ford and built down to a price (even compared to VX's you can see where the pennies have been shaved). So ford may have gone as far as using the lower temps to get away with a less well engineered turbo (mercedes would never do that would they ). Also the TDDI engine has a water/gas cooler prior to the EGR to lower the inlet temp further (and not just by less O2).

Thoughts?

i too now have a focus TDDi estate (02 plate) and the egr has just had the wires cut off it at some point in its life, it appears. the car doesnt smoke, so i presume it will pass an MOT ok when the time comes, and drives as well as a focus TDDi ever will, i think!

 

[snispo]

will that do any good to my 320 cdi 2001. estate? it is smoking a lot when I accelerate. I bough ir recently and i intend to do all necesary to get rid of the smoke. my previous c class 2.2l used to smoke a lot too, fortunately (or un-) I crashed it in the snow.
I hate smoke.

 

[giuseppe]

Fascinating discusion, how, where or from whom can I get the bits and pieces to do the job please, where can I get shrink wrap from, ??.

thanks in advance.

 

[dieselman]

Fascinating discusion, how, where or from whom can I get the bits and pieces to do the job please, where can I get shrink wrap from, ??.

thanks in advance.

Any electronics supplier, Maplin being convenient.

 

[RobWheatley]

Made up and fitted my EGR by-pass today, Easy to make up and the pin outs for my S2002 320CDi (W220) were:
MAF Pin 24 ECU plug 3
EGR signal Pin 50 ECU plug 2
12 volt supply Pin 37 ECU plug 2

I made it up using a computer "molex" plug & socket just incase I ever wanted to remove/replace it, that way the connections to the main ECU harness can be left in place (I stripped about 10 mm of insulation and then soldered them to the wires & wrapped in insulation tape) and a "new" shunt just plugged in.

I did make the mistake of leaving the vacuum pipe to the EGR valve disconnected & the connector off, when driving it there was no smoke but it was really down on power, put the pipe back on and the power came back.

Im guessing that the valve must allow air into the vac system and stop something else (turbo) working.

Now I have all the power back and no smoke (well only the smallest puff of smoke on hard kickdown or flooring it from a standstill)

Took it for an MOT straight after fitting it and it passed the emmissions with ease.

If anyone wants the part numbers I got them from Maplins:
QL76 = IN4004S diode
M1K = 1k ohm resistor
M470R = 470 ohm resistor

I would like to say a big THANK YOU to Dieselman and all involved in the making of this thread.

Really should be a STICKY.....................:idea::idea::idea::?::?::?:

 

[maxx2it]

egr electronic ...

hello ..

I just replaced my 210 and 270 W with a beautiful c30cdi amg sw.

I would do to alter the 'egr even at this, but I have a problem:

valve control is not implemented but is a pneumatic total electronic control

as the latest series W211 (code Mercedes 6461400860).

some of you have made changes on this type of egr?

Thanks

max

 

[RobWheatley]

Hi All
Bit of an update on the results so far with my car.
I changed the route to work about a month ago due the amout of traffic, the new route is mainly narrow twisty lanes with a lot of hills, junctions etc My car had been doing between 28-32 mpg on this new route, this week with the EGR bypass in place it has been doing 35.7-39 mpg, same roads and same amout of traffic as before, now I have calculated thats about a 10-20% increase, could the EGR have been making that much of a difference??
On the way home (some motorway & lanes) I am now seeing an average of 46, up from 40-42 again an increase of 10-15%
I have also noticed that when on the motorway on and off cruise, it is much more consistant, before I could always feel it surging when going up hills at a constant throttle setting, the speed would vary by about 2-3 mph and it felt like I (or the cruise) was hitting the throttle then backing off, that has stopped now.
Smoke wise well what a difference, one of my work colleagues followed me on the way home about a month ago, he ended up backing off as he could not see (or breathe) due to the smoke. He followed me on wednesday to let me know if there was smoke under load. Yesterday morning when I got to work he told me there is NO smoke at all now, just one puff as I pulled out of the car park but nothing under load.

Will keep a check on the computer to see what the average is (i reset it) it was 36.6mpg at an average speed of 37mph over 4300 miles, so far its now 40.5mpg @ 36mph over 300 miles.
I haven't noticed a longer warm up time as some have reported.
Oh and so far it has not gone into Limp Mode, it was before when on the motorway.
Rob

 

[dieselman]

It sounds like you had a problem with the EGR valve jamming open, so the results you now have are quite possible.

Please keep up the monitoring.

 

[amb67]

Is this mod possible on a 2004 E320 CDI, I was led to believe that I had an electronic EGR rather than vacuum controlled?

Currently returning about 32mpg on average (local runs) and I do see some light smoke from the rear when kicking down to move swiftly.

Thanks