EGR Opens @ What RPMs? - Diesel Forum

Rich807 · 09-06-2006, 04:08 PM

1. Just curious if anyone knows when the EGR valve is recirculating the exhaust i.e. what rpms

and

2. Is it tied to fuel delivery or just rpms? i.e. if you're totally off the throttle, say going down a hill, is it opening and closing based on throttle position or staying in a position based on indicted motor rpms?

Thanks in advance.

TimsDiesel · 09-06-2006, 04:15 PM

Maybe throttle position too? I know when going down hill or coasting if I come up off the pedal the truck gets bone quiet.

johnmart · 09-06-2006, 04:47 PM

There probably several parameters that determine when and how much the EGR valve is opened. One that is very important is that the Manifold pressure has to be less than the exhaust back pressure. I see no reason for the EGR to open under deceleration if it's stated purpose is to dilute and cool the combustion process to reduce NOx.

Tim,
When you are coasting, the fuel is shut off so all your 6.0 is doing is pumping air.

TimsDiesel · 09-06-2006, 05:44 PM

Cool, that makes sense. Thanks.

roofeditor · 09-07-2006, 06:42 AM

[ QUOTE ]
There probably several parameters that determine when and how much the EGR valve is opened. One that is very important is that the Manifold pressure has to be less than the exhaust back pressure. I see no reason for the EGR to open under deceleration if it's stated purpose is to dilute and cool the combustion process to reduce NOx.

Tim,
When you are coasting, the fuel is shut off so all your 6.0 is doing is pumping air.

[/ QUOTE ]

I've driven around with the Ford WDS in cab computer hooked up and with this you can actually see EGR opening and how much open. At full throttle it's either closed or mostly closed, at idle is is mostly open and often fully open. RPM, throttle position, EBP, all factor in.

In real world information useful to you, the less time spent at idle the less the EGR is open and the less there is to get the infamous EGR build up......so don't idle much, keep it at full power [img]/ubbthreads/images/graemlins/grin.gif[/img] and your truck will run better.

Additionally I have tinkered with the TS and Quadzilla go fast boxes and I notice that the box alters timing and fuel mixture so the EGR gets confused and tries to compensate with much sooner and much higher EGR openings. This I'm sure of.

SCT claims they can alter EGR openings and timing in the lesser amount but this will "fubar" EPA emissions......if that sort of thing bothers you.

Back to reality. A stuck open EGR will "fubar" everything, emissions, MPG, power, longevity etc.

Rich807 · 09-07-2006, 11:18 AM

Good post.

Btravelen · 09-09-2006, 01:40 PM

I have seen a list of flash updates for the 6.0L and one included a new EGR strategy of limiting the EGR being open at idle. I have also seen discussion of this in the forums, but now I can't seem to find it.

I don't believe it's correct to say that at idle the EGR is open and stays open. The computer limits the the amount of 'open' the EGR is at idle. Maybe a tech with knowlege of this will chime in.

**teamroper60** · 09-09-2006, 02:42 PM

[ QUOTE ]
I don't believe it's correct to say that at idle the EGR is open and stays open. The computer limits the the amount of 'open' the EGR is at idle. Maybe a tech with knowlege of this will chime in.

[/ QUOTE ]

Depending on which flash a person has, it is possible for the EGR to be open at idle. Ford tried that as a way to quiet the idle. They have since changed their minds on that, due to clogging.............. (imagine that!! LOL)

Rich807 · 09-09-2006, 07:38 PM

[ QUOTE ]
I have also seen discussion of this in the forums, but now I can't seem to find it.

Maybe a tech with knowlege of this will chime in.

[/ QUOTE ]

Same here on both counts. Still hoping either a knowledgable tech or speed shop person will chime in on when this thing is actually open and closed.