After removing egr system, I left the sensors plugged to the egr valve etc and just zip tied them near original location to fool the stock ECU. I then plugged the MAF señor back in to the air box lid to keep check engine light off.

However, when I did this the fuel mileage decreased significantly so I tried unplugging the MAF again and the mileage immediately improved.

Why would this make a difference when it cannot mechanically open the egr valve etc since it isn't even connected to the engine?

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05 Blu LIM, OME GDE Tbo, wk II 245/75/17, KC Lights, bull bar, 195K H TC
05 Blu Lim, Dayton, GDE HT, 255/75/18 , 210K , H TC
06 Bla Lim, GDE Eco, Destination AT 245/75/17, 151K, H TC
06 D Khaki Lim 126K wkII Eur TC
05 D khaki Lim 145k refurbishing
All CRDS: Fumoto, Lift , Fan Shroud mod, fuel head Gen II, SAMCOS,self TB, 2 Mic filt, Hayden

Is the FCV still in place and are you tuned?(I see you have many jeeps in various states)

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2006 CRD - GTB2056 turbo by Dieselguy86, Eco Trans Tune, Lift Pump, Week's, HDS Tstat, Racor Filter, ARP's, OME 790's+Top Plate, JBA 2.5", JBA UCA, Moab's+265/75R16, ARB Bull Bar, 4.10's, TrueTracs

What do you mean by "immediately."
Are you reading off the EVIC?
If so, I wouldn't trust it.

I would try to get it tuned so you can finally dump those non functioning parts.

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U.S. Army Retired

Do you still have the FCV in place? IF so, have you removed the flapper butterfly plate out of the FCV? IF not, you need to do so!
Removing it will not trigger any DTC's.
See this:> viewtopic.php?p=914265#p914265

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Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount
98 Dodge Cummins 24 Valve

The particular jeep in question is the 2006 dark khaki one in signature. Original tune and put on the weeks II kit and thats why I plugged MAF back in. I didn't think it would make any difference with weeks kit in but my daughter has been driving it out of town in college. I drove it 200 miles saturday and got about 26 MPG and same 200 miles back Sunday and got over 29 MPG with similar conditions but I noticed the drop on way over on road I drive quite often and unplugged it before the drive home (but usually drive a different jeep CRD where I generally go hunting on weekends). I did hand calculate it, I normally wouldn't have filled up at those times but I did because of noticing this. The EVIC actually said about 29MPG and 31.5MPG respectively.

Only thing I could think of is whatever the ECM reverts to without a MAF signal must have resulted in a leaner mixture than usual. I am going back next week, guess I could try it again and see what happens. In the meantime will just leave it unplugged. I was planning on trying one of the YETTI tunes on this one.

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05 Blu LIM, OME GDE Tbo, wk II 245/75/17, KC Lights, bull bar, 195K H TC
05 Blu Lim, Dayton, GDE HT, 255/75/18 , 210K , H TC
06 Bla Lim, GDE Eco, Destination AT 245/75/17, 151K, H TC
06 D Khaki Lim 126K wkII Eur TC
05 D khaki Lim 145k refurbishing
All CRDS: Fumoto, Lift , Fan Shroud mod, fuel head Gen II, SAMCOS,self TB, 2 Mic filt, Hayden

ww diesel look down a few posts below yours in the link you sent

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05 Blu LIM, OME GDE Tbo, wk II 245/75/17, KC Lights, bull bar, 195K H TC
05 Blu Lim, Dayton, GDE HT, 255/75/18 , 210K , H TC
06 Bla Lim, GDE Eco, Destination AT 245/75/17, 151K, H TC
06 D Khaki Lim 126K wkII Eur TC
05 D khaki Lim 145k refurbishing
All CRDS: Fumoto, Lift , Fan Shroud mod, fuel head Gen II, SAMCOS,self TB, 2 Mic filt, Hayden