EGR questions
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EGR questions
Im in the process of replacing the egr tube on my 98 fl50 and I am experiencing the rusted on conector in the manifold, i was just curious if sealing off the egr would cause a decrease in mpg
Post Fiend
Joined: Feb 2000
Posts: 11,496
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From: Kansas
Welcome to the forum! 
How do you plan on sealing off the EGR? There are a lot of vehicles out there were the EGR has plugged up and they are still driving around with no noticeable issues. With that said the EGR does serve a purpose.
How do you plan on sealing off the EGR? There are a lot of vehicles out there were the EGR has plugged up and they are still driving around with no noticeable issues. With that said the EGR does serve a purpose.
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Aside from the EGR system failing a bunch of tests and failure to operate in a normal fashion, it will set one code (usually the first one to test fail), light the CEL and never be addressed again because a bit is set in program to ignore the system operation.
.
The system provides two functions.
1. The, EPA mandated reduction in NX emmissions for that year.
2. The small improvement in fuel mileage the EGR operation allows as a side benifit.
.
Otherwise it will be transparent to driving in most cases.
The improvment in fuel mileage comes from all the actions associated with EGR operation.
1. The fuel is reduced (cut back), saving fuel.
2. The ignition timing is advanced because the mixture is so lean it needs more advance to light the cylinder due to the exhaust gas allowed to enter back into the intake tract. A lean mix of this nature is very slow on flame propagation once fired so needs to end at the same relitive piston position after top dead center on the power stroke event..
3. The exhaust gas cools down the combustion temps to reduce NX emmissions. This is the principal reason it is on the motor (EPA) mandate or any other system to accomplish the same end result.
.
More than you wanted to know but others may be interested in a deeper understanding of its (EGR) existance.
.
The system provides two functions.
1. The, EPA mandated reduction in NX emmissions for that year.
2. The small improvement in fuel mileage the EGR operation allows as a side benifit.
.
Otherwise it will be transparent to driving in most cases.
The improvment in fuel mileage comes from all the actions associated with EGR operation.
1. The fuel is reduced (cut back), saving fuel.
2. The ignition timing is advanced because the mixture is so lean it needs more advance to light the cylinder due to the exhaust gas allowed to enter back into the intake tract. A lean mix of this nature is very slow on flame propagation once fired so needs to end at the same relitive piston position after top dead center on the power stroke event..
3. The exhaust gas cools down the combustion temps to reduce NX emmissions. This is the principal reason it is on the motor (EPA) mandate or any other system to accomplish the same end result.
.
More than you wanted to know but others may be interested in a deeper understanding of its (EGR) existance.
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JCastellaw
1987 - 1996 F150 & Larger F-Series Trucks
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Jan 16, 2004 11:35 AM
