I recently found that I can get 10-20% better highway MPG (I'm on E85 and every little bit helps), by using the EGR hardware most people ripped off and threw under the workbench a few years back. Surprisingly the stock EGR hardware and settings for my 96530706 ROM gives me ~2 extra miles per gallon. When you are going from 17 to 19 mpg that is a gain of over 10%. At 15,000 miles a year that saves me $350 at current prices

Food for thought: http://www.swri.org/3pubs/ttoday/Sum...n-and-Cool.pdf

Are any of you using EGR to get better highway MPG?

Has anyone tweaked the EGR Duty tables to increase MPG in closed loop cruise?

 

My mileage increased after removing EGR. Stock turbo and stock motor on my car.

 

8426 thanks for commenting. What ROM are you on and what changes did you make to the settings after removing the EGR stuff?

 

My mileage definitely decreased once the system was disabled. Once enabled my MPG went up. I have an Evo 9 running tephra V7.

 

I use my EGR system for this exact reason MPG, in chicago 93oct isnt cheap :/

I also brought this up in a older thread, about how the EGR helps the MPG but some people say other wise, not sure maybe its in the tune or set up?? I noticed a huge difference in the MPG when I got mine in working order after buying the car, And mine has a decent tune on it. I easily went up
2-4 MPG with it in working order.

 

isnt it true that by recirculating exhaust gas, it helps to regulate combustion chamber temps and minimize NOx. to my knowledge, theres no true benefit of deleting the egr system

 

I'm up in the air with it. I recently fixed the hose going to my egr and suddenly seem to get less MPG than when it was hooked up.... Thinking about just getting rid of it all together.

 

Engines don't run on exhaust, they run on gasoline and oxygen.

Everyone I have ever known has removed EGR for gas economy and performance purposes. It is simply there for emissions.

 

I removed mine long time ago. no issues here except some awesome back fire from unburned fuel

 

food for thought:

The exhaust gas, added to the fuel, oxygen, and combustion products, increases the specific heat capacity of the cylinder contents, which lowers the adiabatic flame temperature.

In a typical automotive spark-ignited (SI) engine, 5 to 15 percent of the exhaust gas is routed back to the intake as EGR. The maximum quantity is limited by the requirement of the mixture to sustain a contiguous flame front during the combustion event; excessive EGR in poorly set up applications can cause misfires and partial burns. Although EGR does measurably slow combustion, this can largely be compensated for by advancing spark timing. The impact of EGR on engine efficiency largely depends on the specific engine design, and sometimes leads to a compromise between efficiency and NOx emissions. A properly operating EGR can theoretically increase the efficiency of gasoline engines via several mechanisms:
Reduced throttling losses. The addition of inert exhaust gas into the intake system means that for a given power output, the throttle plate must be opened further, resulting in increased inlet manifold pressure and reduced throttling losses.
Reduced heat rejection. Lowered peak combustion temperatures not only reduces NOx formation, it also reduces the loss of thermal energy to combustion chamber surfaces, leaving more available for conversion to mechanical work during the expansion stroke.
Reduced chemical dissociation. The lower peak temperatures result in more of the released energy remaining as sensible energy near TDC, rather than being bound up (early in the expansion stroke) in the dissociation of combustion products. This effect is minor compared to the first two.

It also decreases the efficiency of gasoline engines via at least one more mechanism:
Reduced specific heat ratio. A lean intake charge has a higher specific heat ratio than an EGR mixture. A reduction of specific heat ratio reduces the amount of energy that can be extracted by the piston.

EGR is typically not employed at high loads because it would reduce peak power output. This is because it reduces the intake charge density. EGR is also omitted at idle (low-speed, zero load) because it would cause unstable combustion, resulting in rough idle. The EGR valve also cools the exhaust valves and makes them last far longer (a very important benefit under light cruise conditions).[citation needed]

Since the EGR system recirculates a portion of exhaust gases, over time the valve can become clogged with carbon deposits that prevent it from operating properly. Clogged EGR valves can sometimes be cleaned, but replacement is necessary if the valve is faulty.

 

timmiii - thanks for your comment. I am also seeing a 10% increase in MPG when cruising through the use of EGR. Are you using the stock EGR duty table settings in V7?

 

Blowngasket - good info thanks. Did you play around with the EGR duty cycle settings at all to see if you could improve mileage?