How an EGR works

[musclemerc]

I've been getting a few PM's lately on this subject and just thought I would share some info I gathered on the topic. There are alot of guy's out here running delete kits and just turning the EGR function off in their tune. Some of you are fine with the side effects of doing this but for the guy's concerned and asking questions weather to delete or not to delete the EGR this info is for you. The EGR does quite a bit in a modern engine especially in a high compression engine more so than others (our car's are indeed high compression). The EGR 's main function is to recirculate exhaust gases back into the upper intake track. About 5~15% of the exhaust gas is recirculated. The NOX that's produced in the exhaust has a valuable use in a combustion chamber. When exhaust temps reach 1600deg. C the valve alows the exhaust to be introduced into the combustion chamber and it has a cooling effect that assists in keeping exhaust temps at bay and reduces the amount of NOX produced. The EGR also can allow the vehicle to run a lower octane without the chance of detonation. The PCM will allow more ignition since the detonation threshold is lower. So removing an EGR will result in more emmissions, less fuel economy, a greater chance for detonation and higher exhaust temps. So the question is why would anyone remove a device that does so much? Here's some info I found to be a great help in explaining the proper function of an EGR: http://www.aa1car.com/library/egr.htm

Happy Maraudering! :burnout:

[SpartaPerformance]

I would agree that there is no reason to delete it but it's only for emissions purposes, anytime you introduce an inert gas such as exhaust into an engine it reduces the efficiency of that engine. The reason to not delete it is that at WOT it's closed therefore not recirculating those spent gasses into the combustion chamber anyway.

[Mike M]

The NOX that's produced in the exhaust has a valuable use in a combustion chamber. When exhaust temps reach 1600deg. C the valve alows the Nox to be introduced into the combustion chamber and it has a cooling effect that assists in keeping exhaust temps at bay. The NOX also can allow the vehicle to run a lower octane without the chance of detonation. The PCM will allow more ignition since the detonation threshold is lower.

Happy Maraudering! :burnout:

Kinda....
It not so much that it "re-introduces" NOX back into the engine but more to do with lowering combustion temps so NOX is not made in the first place.

[RR|Suki]

I would agree that there is no reason to delete it but it's only for emissions purposes, anytime you introduce an inert gas such as exhaust into an engine it reduces the efficiency of that engine. The reason to not delete it is that at WOT it's closed therefore not recirculating those spent gasses into the combustion chamber anyway.

I was just gonna say that. The idea that it will prevent detonation is weird to me (I guess unless you have light throttle ping issue) because at WOT the valve stays closed, so if it really does prevent detonation how is it going to prevent detonation where it really matters, when the valve is shut anyway :confused:

[Mike M]

It is amazing how much detonation you will have in a normal car if it stops working under normal driving.
My specialty is drive-ability/fuel injection/engine performance and through the years i can't tell you how many EGR valves, EVP sensors and clogged EGR ports, and stuck open EGR valves I have replaced and serviced. At one point I stocked just about every Ford EGR ever made (and other makes).

When NOX standards were introduced, EGR valves helped out and the manufacturers tuned there cars to work with EGR. In a perfect world we wouldn't care about NOX and we would not have them on any cars.
But if you have one, disconnected it or disabling it will generally allow detonation to occur. I think my tune has it disabled and I would love to try enabling it again (not sure how to modify the tune-no option in my Predator).

I run 110 octane in my car always, but this past week due to a fuel gauge problem I was forced to put 91 octane in and man oh man it pings anything over light throttle. If my EGR was enabled I don't think it would be a problem.

[-Matt-]

It is amazing how much detonation you will have in a normal car if it stops working under normal driving.
My specialty is drive-ability/fuel injection/engine performance and through the years i can't tell you how many EGR valves, EVP sensors and clogged EGR ports, and stuck open EGR valves I have replaced and serviced. At one point I stocked just about every Ford EGR ever made (and other makes).

When NOX standards were introduced, EGR valves helped out and the manufacturers tuned there cars to work with EGR. In a perfect world we wouldn't care about NOX and we would not have them on any cars.
But if you have one, disconnected it or disabling it will generally allow detonation to occur. I think my tune has it disabled and I would love to try enabling it again (not sure how to modify the tune-no option in my Predator).

I run 110 octane in my car always, but this past week due to a fuel gauge problem I was forced to put 91 octane in and man oh man it pings anything over light throttle. If my EGR was enabled I don't think it would be a problem.


Why the hell are you running such a high octane? What HP level are you at?

[Mike M]

12 psi, since I only drive it occasionally I fill the tank up with 110 and its last for months and months. I have a lot of cars.

[-Matt-]

12 psi, since I only drive it occasionally I fill the tank up with 110 and its last for months and months. I have a lot of cars.


Not PSI... HP...

I make almost 500rwhp on a SAFE daily pumpgas tune with that amount of boost... sounds a little overkill... thats all. Intrested to see what your tune looks like if it pings on 91.

[Mike M]

Nothing special as far as HP goes. When I had 9psi the rear wheel HP was 412 (been awhile), but the added 3 psi must be good for at least 50+ HP. I guess that comes out to 500-550 engine HP.

Is your EGR enabled? I assume mine is not but would like a program to view my tune.

[musclemerc]

Hey Mike, Thanks for your input. I appreciate it!

[RR|Suki]

Nothing special as far as HP goes. When I had 9psi the rear wheel HP was 412 (been awhile), but the added 3 psi must be good for at least 50+ HP. I guess that comes out to 500-550 engine HP.

Is your EGR enabled? I assume mine is not but would like a program to view my tune.

I run prob 520+whp maybe more if I believe the calculators on 93oct. EGR is off in the tune, and I have 0 troubles :confused: If the timing is set for 110, even in the part throttle ranges, seems like that's more the cause of the ping, and the EGR wouldn't really solve that much if the timing is that advanced. But that's just me.

[musclemerc]

Is your motor low or high compression? If it's low compression that explains it.

[RR|Suki]

Is your motor low or high compression? If it's low compression that explains it.

not really, timing is adjusted for all those things, I can avoid knock by sticking to 10:1 ranges sure, and I do use that trick, for WOT in that my WOT timing is very mild. However my part throttle timing is more in the area of the MBT tables. All I'm saying is that it seems like if the timing tables including the part throttle were tuned to run with 110, running 91 would cause knock EGR on of off at part throttle.

[-Matt-]

I run prob 520+whp maybe more if I believe the calculators on 93oct. EGR is off in the tune, and I have 0 troubles :confused: If the timing is set for 110, even in the part throttle ranges, seems like that's more the cause of the ping, and the EGR wouldn't really solve that much if the timing is that advanced. But that's just me.

I as well have my EGR welded closed and deletyed in the tune with ZERO problems...

And thats what i was getting at... why be tuned for 110 octane for 500-550 at the crank? Im surpassing that a good bit on a safe 15* 93 octane tune with NO PING on 91.. I dont think the EGR has anything to do with that at all


Is your motor low or high compression? If it's low compression that explains it.

I still dont think it matters...


not really, timing is adjusted for all those things, I can avoid knock by sticking to 10:1 ranges sure, and I do use that trick, for WOT in that my WOT timing is very mild. However my part throttle timing is more in the area of the MBT tables. All I'm saying is that it seems like if the timing tables including the part throttle were tuned to run with 110, running 91 would cause knock EGR on of off at part throttle.

Again what i said above... doesnt make sense

[martyo]

I have a lot of cars.

This makes me smile! :D

[Zack]

\ Im surpassing that a good bit on a safe 15* 93 octane tune with NO PING on 91.. I dont think the EGR has anything to do with that at all


15 degrees of timing at 12psi leaves about ZERO margin for error, on 93 octane to boot.

Why do you keep making SAFE in big bold letters? LOL

[Mike M]

This makes me smile! :D


I knew it would!

[-Matt-]

15 degrees of timing at 12psi leaves about ZERO margin for error, on 93 octane to boot.

Why do you keep making SAFE in big bold letters? LOL

Andy said it was real safe... had plenty to go if we wanted but didnt think we should push it on the stock rods..

welcome back BTW

[Mike M]

I never said my car was tuned for 110 octane.
I did say I only run 110 octane. It is probably tuned for 93 (premium fuel). Unfortunately all that is available is 91 (cat urine).

Since I only drive it occasionally, I have no problem filling it up with 110. I could probably cut it 4:1 but I choose not to.

[musclemerc]

What up Zack? Good to see you post.


15 degrees of timing at 12psi leaves about ZERO margin for error, on 93 octane to boot.

Why do you keep making SAFE in big bold letters? LOL