Anyone reactivate EGR for better mpg?

[honda_vtec2]

Originally Posted by jollyGreenGiant

VAG-COM adaptation for EGR plays with things like IQ and timing along with EGR, I never had any luck with reduced EGR adaptation, it effected too many other things for my liking and I too received a 3-4 mpg drop in mileage with it adapted on it's lowest setting along with a similar drop in torque. There's better ways to handle the EGR than through the adaptation method on the rotary pump TDI's IMO.

I could be wrong, but it appears that reduced EGR adaptation must be followed with advanced timing adaptation to offset the retard of combustion. I've played a bit, but still learning, so i turned it back to stock calibrations.

When i first got this TDI, EGR hose was detached from the valve. Mileage was around 900km per tank. So i plugged it back in and mileage went up a slight bit, to around 950km per tank with the same non-vented fueling /driving conditions. This was measured briefly with 17' low profile wheels.

[jollyGreenGiant]

Originally Posted by honda_vtec2

I could be wrong, but it appears that reduced EGR adaptation must be followed with advanced timing adaptation to offset the retard of combustion. I've played a bit, but still learning, so i turned it back to stock calibrations.

When i first got this TDI, EGR hose was detached from the valve. Mileage was around 900km per tank. So i plugged it back in and mileage went up a slight bit, to around 950km per tank with the same non-vented fueling /driving conditions. This was measured briefly with 17' low profile wheels.

The real question is, does raising the EGR adaptation to the highest value ( max EGR ), increase IQ and timing parameters and thus fuel economy? A scientific analysis on default and max settings with a couple tanks of carefully logged consumption along with some full load logs of 004,003,011 with default and max values may shed some light on the subject. Any volunteers?

This time of the year is bad to be doing this kind of thing also, the weather at least in my neck of the woods is too variable.

[honda_vtec2]

Originally Posted by jollyGreenGiant

The real question is, does raising the EGR adaptation to the highest value ( max EGR ), increase IQ and timing parameters and thus fuel economy? A scientific analysis on default and max settings with a couple tanks of carefully logged consumption along with some full load logs of 004,003,011 with default and max values may shed some light on the subject. Any volunteers?

This time of the year is bad to be doing this kind of thing also, the weather at least in my neck of the woods is too variable.

I'd volunteer, but the weather up here is fluctuating a lot to get good results. If this thread is still going come spring. I'm in. The last time i played with the EGR settings on the car. It didn't drive as nice, so i went back to stock. I took a small drive around the block and didn't even get to the point of starting logging. I'm not sure if this is due to an intake build up of soot. Last time i measured about 1-2mm or oily stuff around the EGR valve.

My car is currently set with the following, so i'm not sure if i'm a candidate:

1Z engine
ALH pump
stock dsla 150p 706 injectors .170
basic timing 53/127
iq 2.8
timing adaptation 33000 (+2.9 degrees advanced)
14 inch wheels with 185-70 14 (33 psi all around)

I would put timing right on blue, removed any adaptations and test. Does that sound right for stock settings.

Test scenerio

Fill tank to brim (vented)
log a test run roughly 110km at around 3am, when there is limited traffic on the hwy with cruise set at 100kph, rpms roughly sitting at 2163. Stop, refill tank to brim (vented) adjust settings to whatever EGR adaptations. Continue test. Then measure, graph, log whatever fuel was used during the 2 scenerios. I don't think i can do a full tank test.

That's the idea, i think, correct me if i'm off.

[EngineEngineer]

Ladies and Gents;

Before you go out and do some home brewed testing... It may be worth doing some research first. As a mechanical engineer specializing in diesel enignes this question is quite easy for me to answer. In general, EGR almost always comes with a BSFC (brake specific fuel consumption) penalty. One of the reasons for running EGR is to lower NOx but engineers always walk the fine line of the NOx VS PM (particulate matter) tradeoff. However, you have to remember that the lack of EGR creates higher temperature combustion, more NOx (since it is formed during high temperature combustion,) higher turbo temps (which can lead to lower efficiencies,) higher EGT's and so on. In the SAE (Society of Automotive Engineers) publication "Diesel Emissions and their Controls" written by Dr. Majewski and Dr. Khair a very specific example of this principle is detailed. A study on the effect of EGR versus injection timing retard was performed on a heavy duty diesel since both of those situations can be used to reduce NOx. The baseline BSFC was .396 lb/bhp-hr and NOx was as high as 3.976 g/bhp-hr. Utilizing timing retard the engine used .449 lb/bhp-hr but NOx was lowered to 2.804 g/bhp-hr. Finally EGR was used and bsfc came in at .405 lb/bhp-hr (a 2.3% increase over baseline) and NOx was lowered to 2.757 g/bhp-hr. Therefore as I stated earlier and the example demonstrates, EGR almost always comes with a BSFC penalty.

-Nick

[Fix_Until_Broke]

Nick - Welcome to the club and thanks for the reference information.

Stick around - I'm sure there's many more questions that will be quite easy for you to answer

[viersam@gmail.com]

does anyone know what the vacuum should be on the EGR? suction wise?

[jollyGreenGiant]

Originally Posted by viersam@gmail.com

does anyone know what the vacuum should be on the EGR? suction wise?

You should have about 28 in/hg at the vacuum supply to the EGR solenoid and depending on the solenoid's duty cycle you will have a percentage of that reaching the EGR, 50% duty cycle would be about 14 in/hg and so on.

[viersam@gmail.com]

thanks! as you can probably tell in a vacuum idiot maybe you could help me with something else too? I just got my first TDI about a month ago and have had more than my share of problems. The guy i bought it from said the intake was clean. It wasn't. I just removed my EGR and intake and saw that the EGR cooler is clogged almost completely. I am going to solvent soak it and then boil it to remove the carbon build up but I was wondering about blocking out the EGR? how is this done? what are the negative effects? The forums talk about lower mileage but only 1 or 2 mpg? wouldn't having less carbon particles in your engine and not clogging your intake out weigh this?