Disconnected EGR during regen caused regen to stop! - Ford Powerstroke Diesel Forum
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post #1 of 2 Old 11-07-2007, 02:56 PM Thread Starter
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Disconnected EGR during regen caused regen to stop!

I was following this thread with some curiosity...

6.4 EGR Questions

Richard Dawn mentioned unplugging the EGR on his Ford truck which resulted in better gas mileage. I was skeptical that this was actually done on a 6.4 so I tried it myself out of curiosity.

Unplugging the EGR seemed to create less power for my truck. The motor ran erratically and never achieved peak boost (about 36 psi on the gauge is my max). It also resulted in the CEL illuminating. I was afraid to run the truck for a significant distance due to those reasons. Needless to say, I didn't drive it long enough to determine whether or not I got better gas mileage. So I plugged it back in. I assumed that the EGR was stuck in an open position (see why later). FYI, I unplugged the EGR with the motor off, before restarting it and running it.

I remember reading somewhere that the 6.4 regulates max. boost through the EGR. The valve opens progressively the closer you get to max boost feeding itself more exhaust gas. I also remember reading that the EGR closes during a regen and that the valve consists of a "stepper motor". I assumed that the stepper motor meant that the valve would open and close through electrical current by the PCM. I do not know whether or not it has a return spring to return it to an open or closed position.

Since I already had a CEL illuminated after driving considerable miles with the EGR plugged back in, I decided to experiment. Why not? The next time the motor went into regen, meaning a closed EGR valve (right??). I unplugged it again. I was going to see if the EGR stayed closed resulting in a higher peak boost. THE MOTOR IMMEDIATELY CAME OUT OF REGEN! I have driven a couple of hundred mile since then with no regen.

I never did drive the truck after unplugging the EGR during regen to see if it actually created more boost. In hindsight I guess I was surprised due to the abortion of the regen process.

This begs the question of whether or not it would terminate regen resulting from the permanent regen condition due to a removed DPF.

Do not perform this operation if you do not want to see a CEL. Mine is permanently on and I suspect I will have to go the dealer and play dumb to have the code removed.

I know this little experiment is somewhat pointless considering the aftermarket tuners are very close to disabling the regen process for good (excluding KEM). I felt it was my duty to post my observation and see what you all thought.
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post #2 of 2 Old 11-07-2007, 06:08 PM
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As you stated my MIL is on but has been on since truck had 3500 miles anyway for a p2002 code that will not go away. I did not that the truck surged a great deal under hard acceleration , but I plugged this back up today and my mileage went back into the 7's. At 3.22 / gal I will just put up with having to use light pedal pressure to pull. My truck does not have the low end torque as it does with the valve plugged up , but it will pull a hill better and without going into regen, I believe this is were my increase in mileage come into affect. Regen cycle with 20K on board and cutting power,cost alot of pedal effort to make it climb a hill at 3,000 rpm in 3rd gear. With the valve unplugged it will fly up a hill at over 70 mph with out even hardly accelerating with the pedal. I hope this helps , I have done all kinds of things to try to get this truck to 10 mpg and it just aint happening until I get a KEM programmer I do believe and just toss this crap down the river.

Richard N Dawn C

Owner - Campbell Car Carriers
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