Diesel EGR Defeat

[Diesel_Dave]

Originally Posted by Daox

How are you mitigating the increased NOX production now that the EGR is disabled?

He isn't.

If you keep NOx at the same level, FE will be worse without EGR, because you'll have to change something else like retarding timing.

[UFO]

Originally Posted by Daox

How are you mitigating the increased NOX production now that the EGR is disabled?

We had that conversation already, in another thread. This thread is mostly about testing fuel economy by removing EGR, changing nothing else. Instrumentation with the SG is unfortunately problematic, so ABA testing is going to take a while, especially in winter where my biodiesel ratios, ambient temperatures and warm up time vary.

However, if I can verify my defeat circuit emulates the lack of EGR accurately, perhaps the SG can be used as a guideline. I'll have to see, right now I still get an occasional P0402 code, so I need to hook up the VAG COM to see if the expected MAF is too high or too low over the operating range.

[ConnClark]

UFO,

I don't know how your doing your circuit but I think your going to have some troubles. EGR is usually set based on the O2 sensor reading. When the ECU computer senses data from the O2 sensor it will adjust timing and such to try and meet emissions.

To really know how to trick it you need the source code.

Good luck

[JasonG]

The newer CRs I believe have an O2 sensor but the VEs do not.

Adjusting the expected value will probably be necessary.

[UFO]

Jason is correct, there is no O2 sensor. There may be a MAF output dependence on either the engine load or operating temperature, or both. Since the EGR is not modulated with a throttle, I believe the window the ECM expects is wide enough to neglect those effects, if I adjust the appropriate base amount.

[JasonG]

I believe you need to adjust Adaptation block 3.
Bump it up 900-1000 so your reported quantity is at or just below 370.

[RiverRunner]

The guys running the 6.7 L Cummins in Dodge PU's have found unplugging the EGR will provide from 1.5 to 2.5 increase in MPG. You do get a CEL light, but some are using a programmer to fool the ECM and get rid of the CEL.

The trucks warm up real slow in the winter.

My Best to You!

[UFO]

I have modified the circuit and verified it with VAG-COM that is is not setting the CEL. I left the MAF target at 270, where it has always been (I can't adjust it anyway, my VAG-COM is not registered.) To partially offset the loss of EGR warm-up, I installed a grille block.

I also have a 2-tank baseline (more or less) with the EGR connected using mostly pump diesel. The grille block opening is a bit too small, I peaked 215 coolant temperature on my morning drive, so I cut it out a bit more - it's just cardboard for now. I intend to keep the grille block for the portion of the mileage test when I reconnect the EGR.

[Josh8loop]

Originally Posted by UFO

Jason is correct, there is no O2 sensor. There may be a MAF output dependence on either the engine load or operating temperature, or both. Since the EGR is not modulated with a throttle, I believe the window the ECM expects is wide enough to neglect those effects, if I adjust the appropriate base amount.

Your not saying the EGR is just on off control right? I'm pretty sure the N-18 controls the EGR actuator and modulates it's position hence EGR flow rate right?



..

[UFO]

Right, the N18 alone controls the EGR flow. What I am saying is there is no intake throttle to help regulate the flow, like on PD VWs, or my Jeep Liberty CRD.

What I have learned since I wrote that is the EGR level is only checked at idle, so it is irrelevant what the MAF response to EGR is at any other engine condition. At the time I did not have enough output range in my circuit to make the ECU happy. My freeware VAG-COM has been invaluable.