Diesel EGR Defeat

[Diesel_Dave]

Originally Posted by oil pan 4

That is if you believe CO2 is as evil as every one says it is.

Yeah, well I'm not really trying to start that discussion. My point was if there is a concern about CO2, it's global not local. 1 ton less CO2 released in the middle of Alaska would have the same benefit as 1 ton less CO2 in downtown LA--not so for NOx, which wouldn't really affect much of anything in Alaska.

And whether or not CO2 is a problem, I think we can all agree that reducing fuel use is a good thing because of reduced dependence on foriegn oil as well as better use of natural resources.

[oil pan 4]

Using less fuel is good.

There is plenty of "science" behind cold fusion too.
Only problem is all too often the science is skewed by greed.

[UFO]

Originally Posted by oil pan 4

Using less fuel is good.

There is plenty of "science" behind cold fusion too.
Only problem is all too often the science is skewed by greed.

Yes, "science", not science. I'm happy to have this discussion, but let's try another thread shall we?? It's a bit OT.

[Josh8loop]

Just wanted to bump up a good topic. I recently made and installed an EGR delete circuit on my wifes new to us 2005 E320 CDI. It's faily simple and uses one transistor and a few resistors. I found a thermal switch from china that's rated for 75 Deg C that I have purchased to help me make a "dynamic" EGR-one that allows EGR for startup only, and then turns it off. Right now I'm testing the non "dynamic" type circuit until I get my other components. Heres the thermal switch:

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I will be using it with a DPDT relay to enable some fancy switching that will help avoid CEL's while switching between EGR emulation, and actual EGR flow.

[jmcc]

Interesting thread.

Theory: EGR increases the specific heat capacity of the charge, reducing peak temperatures and pressures in the combustion chamber and reducing NOx formation. It effectively slows combustion and reduces efficiency.

Application: MOST engines will have a target MAF map based on some measure of load and speed. In a typical European application, this map will extend across approx. 50% of the full load range (to 10 or 12bar BMEP) and perhaps up to 2500rev/min. This covers legislated emissions cycles and what is generally feasible in terms of EGR tolerance and durability.

Removal: Removing EGR in a modern diesel engine will cause a plausibility error between measured MAF and target MAF. It is also really a bit of a halfway house - if you're really not bothered about NOx then you'd also want to advance the timing and perhaps wind up the rail pressure. You'll get a noisy engine, but better combustion efficiency and hence FC.

Originally Posted by Diesel_Dave

Not sure where you got the information that EGR doesn't operate at max power. I've seen lots of diesels where there's EGR all along the torque curve.

This seems very odd unless you're referring to heavy duty engines or very old engines! I've seen NO Diesel passenger car engines that run EGR at full load. As EGR displaces air, this would reduce performance/increase smoke considerably. This compromise is unnecessary because legislated drive cycles don't include regions of full load operation.

Biofuel: I don't have much to add on this other than that I wouldn't use it on a CR engine until I'd seen evidence of no lubricity issues. Maybe that's out there, but I haven't seen it (possibly my bad!)

Tease: there are easier ways to trick an engine into operating without EGR that would have the added benefit of operating on a manufacturer developed cal...

[Tesla]

Originally Posted by jmcc

Interesting thread.

Tease: there are easier ways to trick an engine into operating without EGR that would have the added benefit of operating on a manufacturer developed cal...

I'll take the bait, how?

[jmcc]

It will depend on the vehicle and technology available, but EGR is generally switched off at cold ambient conditions because of the increased likelihood of misfire. So, my thought (not tested I should add) would be to trick the ECU into thinking its operating at low ambient temperature. Since the IATS generally works on a resistance basis, it should be possible to adjust this feedback.

I don't have more info than that at the moment, but if you have a scan tool and can see both EGR and IAT, you should be able to find out at what temperature this happens and using a multimeter measure the sensor response to temperature as a resistance. If you can then supply an adjustment to this resistance, making the engine think it's at cold ambient, then it will turn off EGR and I expect, advance the timing.

As I say, not tried it but think this may be easier than sending dummy MAF signals.

[Josh8loop]

Originally Posted by jmcc

It will depend on the vehicle and technology available, but EGR is generally switched off at cold ambient conditions because of the increased likelihood of misfire. So, my thought (not tested I should add) would be to trick the ECU into thinking its operating at low ambient temperature. Since the IATS generally works on a resistance basis, it should be possible to adjust this feedback.

I don't have more info than that at the moment, but if you have a scan tool and can see both EGR and IAT, you should be able to find out at what temperature this happens and using a multimeter measure the sensor response to temperature as a resistance. If you can then supply an adjustment to this resistance, making the engine think it's at cold ambient, then it will turn off EGR and I expect, advance the timing.

As I say, not tried it but think this may be easier than sending dummy MAF signals.

I haven't looked into the cold ambient temp deal and EGR shutoff bit, so I'm not sure either way on that. I can say however that when you simulate lower coolant temperatures and lower intake air temperatures the engine will generally go more advanced and add more fuel to reduce cold startup issues. If the fuel quantity remains high during normal operation due to the reported lower temperatures, there goes any FE benefits.

We need to find a way to change the right couple of parameters that won't domino other things and send us in the wrong direction FE wise. I still like the idea of retaining EGR functionality during cold startup(to reduce warm up times). I have received some temperature switches and a couple 12 volt relays that I plan on using to modify my EGR simulator circuit to create "dynamic" EGR functionality.

[jmcc]

A lot of people in this thread seem to forget that the fuelling is controlled by the driver. It is only higher when cold because there are more losses which means the driver goes to a higher pedal demand/fuel delivery to achieve the required output torque.

If timing is advanced and temperature high you will get better FC.

[Josh8loop]

Originally Posted by jmcc

A lot of people in this thread seem to forget that the fuelling is controlled by the driver. It is only higher when cold because there are more losses which means the driver goes to a higher pedal demand/fuel delivery to achieve the required output torque.

If timing is advanced and temperature high you will get better FC.

Your right, driver can affect the MPGs achieved hugely. I'm not talking about that though. I'm talking about how the vehicle control system adds more fuel during cold starts to ease startability, and avoid rough idle. Like you mention this is mainly due to a cold combustion chamber. What is FC?