Does an egr help that much?

[Daox]

Thats not true at all. The 3rd gen Prius uses external EGR with a cooler to run up to 30% EGR mixtures. If they could get better mileage with internal EGR I'm sure they would have.

The Mazda Skyactiv engines also use cooled external EGR.

[Interlocutionist]

So besides the computer control and EGR cooling, what has changed with EGR systems over the years to make it how it is today?
And perhaps more important, would it be possible to retrofit older vehicles with newer EGR technology to improve performance in any way?

[Daox]

That was one of the things I wanted to play with on my Paseo. Alas I haven't had time to actually do it yet.

Here is the thread on it: Increasing EGR flow for better mileage

[oil pan 4]

EGR in diesels hurts fuel economy.

[jakobnev]

Originally Posted by oil pan 4

EGR in diesels hurts fuel economy.

I suspect that having a much larger engine at lower BMEP to keep NOx down would be much worse for fuel economy tho.

[tjts1]

Yeah, theres really no point to EGR other than reducing NOx emissions. If manufacturers were allowed to use lean burn in production engines you would never see EGR.

[mechman600]

Originally Posted by oil pan 4

EGR in diesels hurts fuel economy.

It depends on the application. I build EGR deletes for 15L Cummins ISX engines. My customers that haul lighter loads and/or stay in the city tend to get a small increase in mileage, maybe 15% or so. The real gain is the elimination of the notoriously unreliable EGR valve that plagues these particular engines and the need to replace them every 2 years at a cost of around $1000. My customers with very heavy loads, Super-B Trains at 140,000 lbs in the mountain highways, tend to lose mileage by about 15%. I do not sell them to these guys anymore because they are never happy with the results.

In a pickup or VW TDI where overall load is very light, there will definitely be an improvement with an EGR delete.

[Dieselman]

I don't see how the heavy load diesels get worse MPG after an EGR delete as the EGR valve will be closed anyway due to the load.
Is your delete option just a resisitor mod to drop the MAF reading when the valve should be in operation?

[Dieselman]

Originally Posted by tjts1

Yeah, theres really no point to EGR other than reducing NOx emissions. If manufacturers were allowed to use lean burn in production engines you would never see EGR.

Not quite correct. An open EGR valve reduces pumping losses due to the restriction caused by the throttle flap, without allowing any more oxygen into the cylinders.

[mechman600]

Originally Posted by Dieselman

Is your delete option just a resisitor mod to drop the MAF reading when the valve should be in operation?

No, it is a full block off plate. The EGR motor and position sensor remain intact to keep the ECM happy, but they are not connected to anything. I send a modified signal to the delta-P sensor to make the ECM think EGR is flowing when it wants some.

It doesn't make sense to me either, but data from three heavy haul trucks is what I am going by.