I've been curious to find our for myself whether unplugging the EGR helps with fuel mileage and/or derates the power output on the 4th gens. I've read both ways on this forum.

Here's my experience: The weekend before last I drove 800 miles round trip. 400 miles on the way out with the EGR plugged in, 400 miles on the way back with it unplugged. All interstate driving with a light (700lb.) load in the back and two adults at 65-85mph. I got 16.1 on the way out, 17.5 on the way back. I drove much faster on the way back because the weather was nicer. Also there is more uphill on the way back. I am convinced that unplugging the EGR does indeed yield better mileage. Probably due to the cooler and cleaner intake air.

A few days later I noticed a significant decrease in power under hard acceleration, especially around 55-65mph. Not sure why this wasn't evident when I first unplugged the EGR. I attempted to pass someone on a two-lane and the power just wasn't there. Actually kind of scary. Had this happen one more time last weekend and decided it was enough, I plugged in the EGR. Of course the MIL light didn't go away, and the power was still not there. Fearing a plugged DPF or failed turbo I read and cleared the codes (three codes total, all EGR related). The power was immediately restored. Fuel mileage immediately dropped 2 mpg.

Not trying to start an argument, just stating my experience. Looking forward to the day I can afford a DPF delete.

 

Try unplugging it again. I had a bad experience at 2000 miles into the unplug with the hesitation you described. Plugged in, ran for a hundred miles then unplugged again. No more issues. That was 12k ago.

18.2 mpg all miles hand calculated (18.2-18.4 on meter). No deletes, no funny business, no wishful thinking. Stock G56 3.42 and 4WD. Can't get upset at all about that.

 

Update: After installing 285s I've been getting a miserable 12mpg average empty. Probably in constant regen too since I hadn't been doing a lot of highway driving. Unplugged the EGR again as you suggested and made a run down the highway across the state and back the and yes, you are right- the power wasn't reduced this time. The ECM must only punish you once for that infraction Still about 1.5mpg less than the last time I made the trip (about 16 vs 17.5mpg, & I accounted for the 4% increase in tire diameter on the odometer) with the EGR unplugged, so the decrease must be bigger tires and running them at a lower psi for winter. This was mostly 75-85mph with about 500lbs in the bed and 4 passengers, lots of mt. passes.

Incidentally, at 65mph on the flats I got a steady 20mpg with the EGR unplugged.

 

Darn fellas, I am jealous. If I saw a continuous 18mpg I would be so happy. I think 15 is about the best I get. That is with nothing in the bed, nothing in tow, and two little baby girls in the back of the Mega. Boy I sure do punish that right pedal though!! My 3 yr old always says, "Daddy's gotta get, where Daddy's gotta get!"

 

I'm very very very happy with my 2010. At first, i was regretting having sold my '06 auto a few years back as i got 18 with the cat/muffler and 20.5 without it. This 2010 is getting right at the same as my stock '06 with the cat/dpf/muffler installed. From reading thousands of posts on multiple sites, some have had the same luck but not everyone, even with identical specs. i would say i lucked out.

 

So your telling me with all the deletes you have made your still not seeing 18mpg?? I just bought my truck in November and my better half says she is only seeing 16-16.4 on average. My truck is completely stock. I was banking on the deletes not only giving me power but also higher MPG....kinda one of the things I was counting on in order to justify voiding my warrenty....

 

Driving style will make a huge difference! My commute is 65 miles a day with 1500' elevation change. Cruise at 65 I see 17.5, cruise at 70 I drop to low 16s. I'd test it at 55 but I'd never make it 45 minutes at 55 empty!!
I got the Smarty Jr for two reasons: disable EGR without CEL and adjust speedo for bigger tires coming soon. Code clearing is just a bonus. Did I void my warranty? We'll see, if she ends up at a dealer ever! I'm still not sure on the DPF delete, just for the emission police issue. Now, if I made a stock hollow exhaust...

 

Update: My truck de-rated again with the EGR unplugged yesterday . It lasted ten days or so without. Started the engine, got a message icon on the EVIC and a ding at startup (no message though). Went to pull out into traffic and immediately noticed a loss of power. So I guess my earlier post was wrong- the computer must punish you more than once for unplugging the EGR. Fuel mileage has sure been much better though.

 

Mine does the same thing. I can unplug it and as soon as I start it it has a more noticeable rattle noise under the hood. Has really poor power. I plug it back up and clear the code it goes back to normal.

I think my butterfly valve is closing when I unplug cutting air flow in the engine.

 

is any of the gunk in the intake due to the crankcase venting? doesn't it vent right at the turbo?
I have 13800 miles as of today and about 8000 stock and the rest with the Smarty. I only use the truck to commute 65 miles a day (90% @70mph) or tow 3000-4000 lbs. I'm gonna be out of town next week, but I plan to pull my intake soon and look to see what kind of crap is in there.

 

Please have a camera on hand my friend. Or we won't believe a word you say Just kidding - of course we will believe you, but inquiring minds want to know AND see. Thanks.

 

i promise! anyone that works their truck hard or anyone that idles a lot want to do the same? i'd like to see some different scenarios investigated...

 

I finally got mine running good unplugged on my 4th attempt to unplug.
I was on H&S tech page and they recommended removing the air control flapper too. I pulled the white gear out of the motor instead to keep it from closing.
It runs better than when it was plugged in. Hopefully it will stay that way.

I have these codes but it runs strong.

P02E9 - Diesel intake air flow position sensor circuit high (what's this to much fresh air )
P0405 - EGR Position Sensor Circuit Low
P049D - EGR control position exceeded learning limit

 

Ok, after a white-kuckle experience passing a schoolbus on a mountain 2-lane (really should not have been a problem) I decided I better plug in the EGR again and get my power back . Seriously, I think an '87 Suzuki Samurai has more zip than my truck does when the EGR is unplugged, but the Samurai gets twice the mpgs.

<-- Like my new Avatar?

But first I decided to take a look and see how dirty things were, I didn't want to suck a big cloud of soot into the intake when the EGR opened up for the first time in weeks. What a dirty mess! Why do they even bother putting air cleaners on these trucks when they are constantly inhaling this stuff???


(pictures don't do it justice)

Anyway, I had a thought. One of the codes I've cleared each time was "Fuel-Air Metering out of parameter" or something like that. My question is, does the butterfly valve (partially) close anyway when the EGR is unplugged, does that causes the lack of power? Just curious, as I was thought it was some kind of emissions induced limp-mode, but starting to wonder about the butterfly valve- what's to keep it from cycling when the EGR is unplugged? Boost pressure? (Dad03's post above got me thinking...)

 

I decided to play around with it a bit more. I put the gear back in the butterfly motor, plugged it all back up to clear codes and then unplugged the egr and unplugged the butterfly.

I have always read that unplugging the butterfly will make the red lightning bolt on the dash appear but it did not. In fact it ran the same and threw the same 3 codes as my previous post.

So either way it runs good. I don't drive it much and probably only have 100 miles under the belt driving with it unplugged but so far so good.
This is on a 2011 6.7