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Old 05-18-2010, 12:34 AM   #1 (permalink)
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Does an egr help that much?

How much does an egr valve help in improving fuel economy?

30 MPG is the FE equivalent of a 13 second 1/4 mile.
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Old 05-18-2010, 07:27 AM   #2 (permalink)
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EGR alllows higher compression, more advanced timing, and a slight reduction in the fuel necessary for every combustion event. Properly applied it may have even greater benefits in the future, but they are significant today, and in the early years of EGR (late 60s) many tried to disable the EGR and found the engines would hardly run.

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Old 05-18-2010, 11:33 AM   #3 (permalink)
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Even Todays Vehicles will hardly run if you "try" to disable it.. However if you say learn the routing of the vacuum lines (thanks alldatapro ) Then you can disable it as well as make the car run as normal because it runs poorly because it's technically a vacuum leak depending on how you try to disable. Not sure if any of this makes since to anyone else but hey a new born will do that too ya "lack of sleep and sanity" lol.

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Old 05-18-2010, 11:44 AM   #4 (permalink)
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Well, I think the most extreme case I know of is the gen 3 prius. It runs up to a 30% EGR mix. I'd imagine on that engine not having EGR would be a huge detriment. On any other vehicle who knows. It all depends on the design of the engine.

I started a thread a while back about using more EGR to create a lean burn like effect. I haven't ever had the chance to test it though.
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Old 05-18-2010, 12:34 PM   #5 (permalink)
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I've tried mine disconnected and connected and could never tell the difference one way or the other. Heck the computer doesn't even seem to be able to tell the difference, it doesn't give a code with it disconnected. So I just leave it disconnected because I've heard it helps keep carbon from fouling up the intake that way.

But I would think newer cars are more sensitive that way and EGR could make a real difference.

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Old 05-18-2010, 02:21 PM   #6 (permalink)
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I'm not sure i know new new cars are much more sensitive to it then the older one that basically just run off vacuum because of increasing emissions like the new bmw has egr like a normal then they're also starting to use it for thermal energy from the exhaust gas to make electricity before it puts it back in the motor. the newer they get the harder it's gonna get to modding for efficiency, power, or anything else without a doctorate in nuclear thingamijigee lol. But hey hopefully we'll start flying our cars too.
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Old 05-18-2010, 08:29 PM   #7 (permalink)
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Originally Posted by carbonaltima View Post
How much does an egr valve help in improving fuel economy?
A little hard to say with certainty.
In my car (3.8 GM with 4L60E trans) the EGR operates only on when the cruise control is operating and when that happens the "Lean run" cycle also kicks in.

How much is due to EGR and how much to "lean run" is unknown.

In any case it all happens inside a black box somewhere and my control over it is nil.

Running on cruise means a reduction of about 10% to 15% in fuel numbers on average over my normal driving style.

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Old 05-18-2010, 10:52 PM   #8 (permalink)
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Well, by the time we make hovercars, we won't have to worry about gas because the antimatter charge that makes the cars levitate will also push them forward
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Old 05-19-2010, 02:41 PM   #9 (permalink)
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I know on most US 1993-2003 GM 3.8 V6s (3800) the EGR being disabled will drop cruising by 1-4MPGs. Deleting it is easy also remove the bolt holding the EGR pipe to the Lower Intake Manifold block the hole with something (tap and plug) do the same to the other end of the pipe and unplug the electrical connector, then ignore the check engine light.
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Old 05-20-2010, 01:03 AM   #10 (permalink)
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EGR is good for everything - do not delete it

somehow this subject keeps being reposted
somebody gets it in their mind that removing the EGR system helps the engine run better and somehow magically increases power output and improves fuel economy

all of that is pure blarney -

EGR does not function at idle or WOT - and does not affect maximum power output .
EGR does function at part load or cruise .

the Primary function of EGR is to add INert exhaust gases to combustion to reduce combustion temperature and by so doing
reduce the formation of the pollutant NOX

EGR improves fuel economy by reducing suction throttling loss and reducing engine compression and reducing engine displacement
while it is active

deleting EGR is going to cause your system to pollute more and it will reduce FE , deleting EGR will have no affect on maximum power available.

and on a 1996 or newer car ;
doing anything to interfere with EGR function is "tampering " with the OBD2 system and a violation of federal law .

bottom line ;
if you do not know EGR theory ....
do not frak with your EGR unless you need to clean out the passages to IMPROVE / INCREASE EGR flow .

Last edited by mwebb; 05-20-2010 at 01:06 AM.. Reason: SPELLING
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