Does an egr help that much?

[oldbeaver]

Originally Posted by oil pan 4

Was your coolant temperature lower on your diesel with no EGR?

Not really, just the same I would say.

A little more noisy, maybe.

Oldbeaver

[mwebb]

Originally Posted by COcyclist

On the VW TDI is does help warm up times. The Exhaust Gas goes through a stainless steel EGR cooler which is tied into the coolant loop. As the exhaust gas is cooled it heats the coolant flow.

.

i would have to check to see if the EGR is active
when cold

if EGR is not active until the engine has reached a certain temperature then the EGR cooler will have zero effect on warm up

remember
the primary function of EGR is to reduce NOX and NOX
does not can not form at low engine combustion temperatures
if active
EGR would NOT enhance the operation of a cold engine

[Xist]

Did you guys just agree and move on?!

[COcyclist]

I can add some personal experience to fuel this debate, at least as far as the VW diesel is concerned. I installed this tune Dynamic EGR Control for TDIs - TDIClub Forums from Malone tuning about two years ago. I also put in a higher temperature Stant thermostat and my highway mpg has gone up about 10%. Click on my fuel log.

Everything I read says that diesels like to be fully warmed up and be supplied with lots of clean, cold air. EGR is hot and dirty and has less oxygen. EGR hurts fuel economy in a diesel in my experience.

[oldbeaver]

Originally Posted by COcyclist

I can add some personal experience to fuel this debate, at least as far as the VW diesel is concerned. I installed this tune Dynamic EGR Control for TDIs - TDIClub Forums from Malone tuning about two years ago. I also put in a hierarchy temperature Stant thermostat and my highway mpg has gone up about 10% . Click on my fuel log.

Everything I read says that diesels like to be fully warmed up and be supplied with lots of clean, cold air. EGR is hot and dirty and has less oxygen. EGR hurst fuel economy in a diesel.

Hello Cocyclist. You wrote the title of my answer. I agree in general on yr opinion. But would like to have facts to sustain it. Did you make a test with a trip computer installed and on the same tract of road, keeping all conditions "ceteris paribus" but EGR? That is the only valid way. Otherwise it is just a suspition based on a (biased) opinion.

In my car I did the same and the effect was opposite. See my fuel log. I wanted to improve FE, disconnected EGR and FE went worse. There are documented reasons for that. Then I reconnect it back, and FE improved.

One cannot rely on fuel tanks FE to get a valid conclusion. From one tank to another, in 700 km travel, many things may change, such as temperature which affect tires, air density and resistance, road surface which is very important, load (passangers and baggage), slope, traffic, extension of continuous driving (it is not the same to drive 700 km in 7 tracts of 100 km each compared to drive 700 km in 40 tracts of 17,5 km), altitude, to mention a few factors that affect FE. Not to mention driving strategies, which may have a 40% effect. And when you want one thesis to win over the other, conciously or unconciously you can make one to be the champion.

Cooler air input makes sense to me, though. What I wish do is to install a trip computer in my car for testing all this mods properly. After that, I will try to install a EGR air cooler, and see what happen, measuring with the trip computer. Compare FE with and without EGR, etc. Explore and test all combinations.

My plan is to use MPGuino, which I already got, for which I am waiting for a mechanic friend of mine who will come to help me.

Regards,

Oldbeaver

[COcyclist]

Originally Posted by oldbeaver

Hello Cocyclist. You wrote the title of my answer. I agree in general on yr opinion. But would like to have facts to sustain it. Did you make a test with a trip computer installed and on the same tract of road, keeping all conditions "ceteris paribus" but EGR? That is the only valid way. Otherwise it is just a suspition based on a (biased) opinion.

In my car I did the same and the effect was opposite. See my fuel log. I wanted to improve FE, disconnected EGR and FE went worse. There are documented reasons for that. Then I reconnect it back, and FE improved.

Oldbeaver, You are correct, my methods are not scientific and as I mentioned, I changed the thermostat at the same time. So it is impossible for me to say which caused the change or if it is the combination of both.

I couldn't tell which diesel you were experimenting with but if I recall correctly some TDI owners have suffered worse mileage by disconnecting EGR without addressing the factory tuning parameters. If you are interesting I can try to find the link on TDIclub.

[COcyclist]

Originally Posted by mwebb

The current VW TDi (diesel) system does use a throttle body type flap near the center of the exhaust to increase exhaust pressure to assist EGR at various times as determined by the ECM and the current VW TDi does have a throttle body type flap in the intake, again it is controlled by the ECM and part of it's function is to assist with EGR. Both of these "throttle body" type flaps are drive by wire, there are no "throttle cables" or any mechanical connections to them, the ECM has control using little motors with position sensors on the flaps. The EGR gas flows from a higher pressure area to a lower pressure area as assisted by the ECM

Could this account for increased mileage with an EGR tune in a VW?

[COcyclist]

FWIW, I recently added a Jeep Grand Cherokee CRD to the fleet. Based on my encouraging results with the VW I will probably get a Green Diesel Eco tune in the near future. From their website- "Available power is increased to 250hp and the torque is also increased along with a broader torque curve.
Fuel economy is increased by 2-4mpg.
EGR is eliminated and turbo lag is reduced significantly.
The swirl motor is turned off and no CEL if the motor has a failure (common problem on this application)". Marketing, not science, however I will update if I notice any improvement. I am doing this for long term reliability and to avoid a potentially costly repair

[oldbeaver]

Originally Posted by COcyclist

Oldbeaver, You are correct, my methods are not scientific and as I mentioned, I changed the thermostat at the same time. So it is impossible for me to say which caused the change or if it is the combination of both.

I couldn't tell which diesel you were experimenting with but if I recall correctly some TDI owners have suffered worse mileage by disconnecting EGR without addressing the factory tuning parameters. If you are interesting I can try to find the link on TDIclub.

Tks a lot. I have TDI Club and I have a TDI car also. Skoda.

I am experimenting with a Mercedes 1993, model diesel turbo, 6 cil in line.

[COcyclist]

Oldbeaver, I think this was the thread I was thinking of. http://ecomodder.com/forum/showthrea...eat-19275.html
Right here on Ecomodder. Lots if good discussion about EGR in diesels. Josh8loop's link inspired me to do the hotter thermostat. He also has a 60 mpg gas log.