egr disable?
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Senior User
Joined: Mar 2003
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From: nova scotia, canada
maybe, but intake vacum is maintained at (efi) wot and the egr works on this vacum the exhaust gas is also forced into the intake from the exhaust gas pressure. i know that some will want to argue that but if they pull an egr tube off and run the engine they will have little to argue with. try it.
egr is disabled at wot to allow the engine to build designed power. its like when your ac system shuts off at wot or 100 calc load. it lets the engine use all avaible for hp and torque.
i have my egr system turned off, its only been one tank but there has been no difference yet in fuel mileage and the highway performance seems better. but more tanks are needed before i decide what if any bennifits there may be. if it makes no difference then i will admit it.
egr is disabled at wot to allow the engine to build designed power. its like when your ac system shuts off at wot or 100 calc load. it lets the engine use all avaible for hp and torque.
i have my egr system turned off, its only been one tank but there has been no difference yet in fuel mileage and the highway performance seems better. but more tanks are needed before i decide what if any bennifits there may be. if it makes no difference then i will admit it.
Last edited by beer boy; Sep 10, 2007 at 07:36 PM.
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From: Long Island USA
One other thing to think about is that the EGR wouldn't add anything (or subtract from) emissions at wide-open-throttle.
At wide open throttle, backpressure is high so you have pressure at the EGR port, and the intake is sure sucking a lot of air so could easily take what the EGR puts out.
But there's no need, because at wide-open-throttle, combustion temps are lower - which is what the EGR is designed to do - lower combustion temps to lower NOx emissions.
So, there's no reason for it to be on at WOT.
At wide open throttle, backpressure is high so you have pressure at the EGR port, and the intake is sure sucking a lot of air so could easily take what the EGR puts out.
But there's no need, because at wide-open-throttle, combustion temps are lower - which is what the EGR is designed to do - lower combustion temps to lower NOx emissions.
So, there's no reason for it to be on at WOT.
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From: Canton, IL
Yes, backpressure is there, which can reduce volume of exhuast gasses, but even though the intake is sucking lots of air, its through the butterfly, not through the vacuum lines. Think path of least resistance.
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From: Long Island USA
Originally Posted by Fishin76
Yes, backpressure is there, which can reduce volume of exhuast gasses, but even though the intake is sucking lots of air, its through the butterfly, not through the vacuum lines. Think path of least resistance.
My point is that it doesn't matter, because the combustion temps are lower anyway because of the inrushing cool air. So the EGR is pointless at WOT.
Otherwise, the EPA would certainly have made it operate at WOT to reduce NOx. Doesn't matter about max power ...
Fleet Owner
Joined: Mar 2003
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From: Blue Hill Township
Originally Posted by beer boy
maybe, but intake vacum is maintained at (efi) wot and the egr works on this vacum the exhaust gas is also forced into the intake from the exhaust gas pressure.
Vacuum on a gasoline normally aspirated vehicle is 16-22 in hg. With the throttle wide open there is little to no vacuum in the intake.
Turning off your EGR isn't going to make much of a difference at all.
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From: Canton, IL
Posting Guru
Joined: Aug 2007
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From: Canton, IL
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From: Madison, SD
Wondering if someone could tell me what guys are hoping to accomplish when they use the "restrictor" gasket, as in a smaller hole, for the EGR valve???? I've been seeing them advertised a few places....
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From: Long Island USA
My '96 t-bird had a stumble on very small throttle applications - using an Autotap, I was able to figure out the EGR was coming on during the stumble.
I put a restrictor in the vacuum line feeding the EGR to keep it from coming on too fast - the hole in the restrictor was probably .010" or so...
It killed the stumble. My '97 cougar 4.6L does the same thing - although much less noticable.
This might be the reason for the restrictor gaskets. Or not
I put a restrictor in the vacuum line feeding the EGR to keep it from coming on too fast - the hole in the restrictor was probably .010" or so...
It killed the stumble. My '97 cougar 4.6L does the same thing - although much less noticable.
This might be the reason for the restrictor gaskets. Or not
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From: Long Island USA
Originally Posted by krewat
I put a restrictor in the vacuum line feeding the EGR to keep it from coming on too fast - the hole in the restrictor was probably .010" or so...
There might be another reason for vehicles with no backpressure... or some other drivability thing with souped-up motors...
Elder User
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Just wanted to throw this out, why, if EGRs are so great why does GM design it's LSX blocks without them. 4.8, 5.3. 6.0 do not use them and make great hp and torque and get without a doubt better fuel economy then a 4.6, 5.4
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From: Long Island USA
Originally Posted by montecarlo31
Just wanted to throw this out, why, if EGRs are so great why does GM design it's LSX blocks without them. 4.8, 5.3. 6.0 do not use them and make great hp and torque and get without a doubt better fuel economy then a 4.6, 5.4
Just kidding...But seriously folks...
My 2001 V10 doesn't have an EGR either - the '99's did.
The EGR system keeps the peak combustion temperatures lower to avoid creating Nitrogen Oxides. If a motor can be designed in a way to allow the peak combustion temperatures to stay lower without an EGR, there's no need for it.
Although, the EPA requires one on passenger cars - I'd love to see how they get around the EPA requirement...
Elder User
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the cylinder can hold x amount of air/fuel. with the egr that is reduced by replacing some of the air/fuel mixture with exhaust. if there is 30% exhuast in the cylinder then there is only 70% air/fuel mixture. if there is less air in the cylinder then there will be less gas. the reason it is shut off at wot is you can not make max power. as far as any gain there is none. you do not loose any performance, and you do gain a little gas mileage. and you stay legal.