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Old 02-04-2010, 05:28 PM   #1
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EGR Modification for better gas mileage?

I was wondering if there is a way to modify the EGR valve tip, where you machine a portion away so EGR is always used by the engine, but still not throw a check engine light by making the EGR valve hang open.

I was reading an article where only 30% of fule is burned in the cylinder and 70% is pushed out.

would this give improved gas mileage?

94 Civic VX is what I am driving.
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Old 02-04-2010, 05:32 PM   #2
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no cuz it acts like a massive vaccum leak. trust me when you have a bad egr valve it falls on its face and has absolutely no power. a bad or sticking egr valve made my mpg drop (95 s10)

the chevettes was blocked when i got the car i hooked it up idled fine reved fine, under a load hell no didnt wanna accept any gas pedal input haha

BUT i dunno could try it but i wouldnt expect much so dont spend too much money hehe
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Old 02-04-2010, 09:36 PM   #3
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Quote:
Originally Posted by onefasteg View Post
I was wondering if there is a way to modify the EGR valve tip, where you machine a portion away so EGR is always used by the engine, but still not throw a check engine light by making the EGR valve hang open.

I was reading an article where only 30% of fule is burned in the cylinder and 70% is pushed out.

would this give improved gas mileage?

94 Civic VX is what I am driving.
Link to the article???? If you want to mess with the EGR, I'd try doing it in a computer controlled way, that way you'd actually get an improvement in mileage if at all. I had some ideas to modify the way the EGR operated in order to improve fuel economy but unless you program it so it actually works somewhat intelligently, you won't benefit from it.
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Old 02-04-2010, 10:00 PM   #4
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^x2
EGR needs to be added only during certain times. It doesn't take much EGR to stall the car when at idle. Adding EGR under full throttle is bad for power. It needs to be phased in gradually as the throttle is opened more.

I've played with the EGR tables in my ecu and didn't see much difference. I also didn't get too crazy with it since exhaust gasses tend to leave a dirty coating in the entire intake.
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Old 02-11-2010, 12:13 PM   #5
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Hi all,
I wanted to say that on my petrol engine (European Honda Civic 1,339cc) the EGR is not only put for environmental reasons (lower NOx) but my ECU also opens the EGR valve as countermeasure when knocking is detected by the knocksensor. This is a more efficient way to fight knock than retarding ignition.
I'm telling this because it's possible for my engine that I can not win any MPG when changing something to the EGR valve.
It was my plan to minimise the EGR opening and probably make some mpg gains, but with the anti-knock function of the EGR I'm not convinced.
It's true that also on my engine there's no EGR opening at idle and low revs (till +/- 1600 rpm).
My EGR is fully integrated in the cylinderhead. All canals are 100% in the cylinderhead (shortest possible distances) and the electromagnetic valve sticks out on top of it.
Guess this is a very good solution to avoid condense and cludging in the system.
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Old 02-17-2010, 06:59 PM   #6
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Quote:
Originally Posted by onefasteg View Post
I was reading an article where only 30% of fule is burned in the cylinder and 70% is pushed out.
i think you just misunderstood what the article was saying. the fuel is burned very close to 100% if an engine is properly maintained, its where the energy goes that is around those numbers.

any internal combustion process that turns heat into mechanical energy has a theoretical maximum efficiency of 40%. that being said, because thats the absolute maximum you'll never see it.

in general, you see about 1/3 of the energy go out the exhaust, 1/3 out your cooling system, and only 1/3 into powering the car. so if you were to say that you were only converting 30% of the energy in the gas to usable mechanical energy you'd be about right.
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Old 03-10-2010, 10:06 AM   #7
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At part throttle (where 90+% of driving happens) EGR improves fuel economy, as long as the EGR is low enough that the mixture still ignites readily. This is similar to WAI, because EGR reduces "pumping losses".

So, more EGR is better, so long as the engine doesn't misfire.
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Old 03-11-2010, 01:45 PM   #8
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Quote:
Originally Posted by Sludgy View Post
At part throttle (where 90+% of driving happens) EGR improves fuel economy, as long as the EGR is low enough that the mixture still ignites readily. This is similar to WAI, because EGR reduces "pumping losses".

So, more EGR is better, so long as the engine doesn't misfire.
EGR can improve fuel economy and decrease emmissions, but there's a limit: once over 10% emmisions and fuel economy get worse.
Reason: the exhaust gas slows down the flaming speed of the burning mixture and this has a negative influence on engine efficency=bad fuel economy.
If there's misfires because of EGR, something's badly wrong.
Emissions of NOx go down of course when increasing EGR (because lower temps), but once over 10% you will see CO and HC increasing. That's why 5 to 10% is a maximum on petrol cars as well for emissions as for fuel economy.
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