Horrible Gas mileage, need suggestions - Page 2 - Jeep Garage - Jeep Forum

Go Back   Jeep Garage - Jeep Forum > Jeep Platform Discussion > Grand Cherokee - WJ > Engine Performance/Intake/Exhaust

Join Jeep Garage Today
Reply
 
Thread Tools Display Modes
 
  #13  
Old 01-08-2016, 06:13 AM
Frango100's Avatar
The beast from Brazil

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 7,423
Thanks: 18
Thanked 386 Times in 373 Posts
Rep Power: 529617
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: Horrible Gas mileage, need suggestions

Run some seafoam or alike through the gasoline, it will clean the combustion chamber, but also the injectors. Dirty injectors will not have a nice spray pattern, which negatively influences the mpg.
How does the engine run, idles smooth and normal power?

__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
Sponsored Links
Advertisement
 
  #14  
Old 01-08-2016, 08:10 AM
Trav1s's Avatar
Member
My Jeep: 2004 4.7 HO WJ
 
Join Date: Apr 2012
Location: Cedar Rapids, IA
Posts: 958
Thanks: 54
Thanked 30 Times in 29 Posts
Rep Power: 2830
Trav1s has a reputation beyond reputeTrav1s has a reputation beyond reputeTrav1s has a reputation beyond reputeTrav1s has a reputation beyond reputeTrav1s has a reputation beyond reputeTrav1s has a reputation beyond repute
Garage
Re: Horrible Gas mileage, need suggestions

Fuel Filter above the rear axle been replaced?

That made a huge difference on my '04 Columbia Ed.

I second the Seafoam - start with it in the gas and see how things go.

How old are the plugs?
__________________
2004 Columbia Edition WJ 4.7 HO
RB4/Moog HD Steering Stabilizer/PML trans pan 10304/ Autometer trans temp and oil pressure gauge/UpCountry springs & OME 10MM Spacers/Bilstein shocks/Rubicon Moabs/255/65r17 Cooper Discoverer AT3/Factory chrome tow hooks/Mopar hitch & a loose nut behind the wheel
Reply With Quote
  #15  
Old 01-08-2016, 08:46 AM
Frango100's Avatar
The beast from Brazil

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 7,423
Thanks: 18
Thanked 386 Times in 373 Posts
Rep Power: 529617
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: Horrible Gas mileage, need suggestions

Quote:
Originally Posted by Trav1s View Post
Fuel Filter above the rear axle been replaced?

That made a huge difference on my '04 Columbia Ed.

I second the Seafoam - start with it in the gas and see how things go.

How old are the plugs?
See first post, already changed external fuel filter and plugs.
Also, a too low fuel pressure would be compensated with a larger fuel injector pulse, which will show in the LTFT figures.
Maybe it would even be better to remove the fuel injectors and let them clean ultrasonic and check the spray pattern.
__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
The Following User Says Thank You to Frango100 For This Useful Post:
  #16  
Old 01-08-2016, 08:52 AM
Member
 
Join Date: Jan 2012
Posts: 86
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1960
Sqall12001 is on a distinguished road
Re: Horrible Gas mileage, need suggestions

Have run sine sea foam throughin the last few months, will try more, and injecting through vacuum line. Might take a week, bit I'll try

Thanks for all the replies so far!!!

-Nick
Reply With Quote
  #17  
Old 01-09-2016, 05:57 PM
Frango100's Avatar
The beast from Brazil

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 7,423
Thanks: 18
Thanked 386 Times in 373 Posts
Rep Power: 529617
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: Horrible Gas mileage, need suggestions

Also the MAP sensor is the #1 input for the fuel injector pulse. A wrong MAP can cause mpg to drop as well. When ignition is switched to run, the PCM takes the actual MAP value as being the atmosferic pressure. So check this value with the local atmosferic pressure, it should read more or less the same.
__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
  #18  
Old 01-09-2016, 07:39 PM
Member
 
Join Date: Jan 2012
Posts: 86
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1960
Sqall12001 is on a distinguished road
Re: Horrible Gas mileage, need suggestions

Good call, will do!!

-Nick
Reply With Quote
  #19  
Old 01-15-2016, 09:58 PM
Member
 
Join Date: Jan 2012
Posts: 86
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1960
Sqall12001 is on a distinguished road
Re: Horrible Gas mileage, need suggestions

Ok, tested Map best I could the other day. Accuweather said Baro was 29.3 ish, actron scanner said 28.1 about 20 miles away with engine not running. I think it read about 12.1" mg under idle.

Thoughts?
-Nick
Reply With Quote
  #20  
Old 01-15-2016, 10:12 PM
Frango100's Avatar
The beast from Brazil

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 7,423
Thanks: 18
Thanked 386 Times in 373 Posts
Rep Power: 529617
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: Horrible Gas mileage, need suggestions

MAP seems to be ok as well. Did you check the coolant temperature and inlet temperature sensors?
Did you check the exhaust back pressure?
__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
  #21  
Old 01-16-2016, 02:04 PM
Member
 
Join Date: Jan 2012
Posts: 86
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1960
Sqall12001 is on a distinguished road
Re: Horrible Gas mileage, need suggestions

Just noticed I posted this in Performance section, ugh, lol. Exhaust pressure will be harder to check for me, but i'll try. What on these am I looking for. Pull o2 sensor, see significant flow out through the hole???

Coolant seems to stay south of 201* always? Gauge is just left of center. AIT seems to coincide with the outside temps, I'll verify w/ Tool tonight to be sure.

-Nick
Reply With Quote
  #22  
Old 01-16-2016, 02:05 PM
Member
 
Join Date: Jan 2012
Posts: 86
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1960
Sqall12001 is on a distinguished road
Re: Horrible Gas mileage, need suggestions

Oh, I do have a remote start, So I know I'll see a slight ! Slight !, Drop in MPG from that, but this tank I'm at about 90 miles to a half of tank ish.

-Nick
Reply With Quote
  #23  
Old 01-16-2016, 02:10 PM
Frango100's Avatar
The beast from Brazil

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 7,423
Thanks: 18
Thanked 386 Times in 373 Posts
Rep Power: 529617
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: Horrible Gas mileage, need suggestions

Normal back pressure seems to be around 1 psi, but depends on the vehicle. Should never go over 5 psi though. Any change to put a low pressure gauge on the 1-1 and 2-1 O2 ports? (can be one at a time)
__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
  #24  
Old 01-16-2016, 06:28 PM
Member
 
Join Date: Jan 2012
Posts: 86
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 1960
Sqall12001 is on a distinguished road
Re: Horrible Gas mileage, need suggestions

Advanced auto rent ??

Ok, checked temps as follows:

Vehicle not run all day. Exterior temp ranged from 33-28 all day via accuweather, Vehicle not started, tested key on engine off::

CTS - 45*
IAT 37*
Evic 30*

Also noticed O2B1S1 was 1.02v
and O2B2S1 was 1.08v

upon start up. Weird its above 1v?

Changing front diff fluid as a precaution and a Just see.. Rear changed a month or 2 ago.

-Nick
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Possible to set mileage in replacement instrument cluster to ACTUAL mileage? The Godfather Grand Cherokee - WJ 6 01-01-2015 04:43 AM
white smoke from exhaust and horrible gas mileage jd31 Trouble Shooting/Problems/Service 33 10-02-2013 03:21 PM
Can I mix High mileage Full synthetic with regular High Mileage? sergioad89 Engine Performance/Intake/Exhaust 8 06-30-2012 07:38 AM
Getting Horrible Gas Mileage Sodelcustoms Troubleshooting/Problems 16 01-20-2010 07:54 PM
4.7L gas mileage... Bigdiesel74 Performance Modifications 15 10-22-2009 10:58 AM

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 07:58 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community

JeepGarage.org is in no way associated with or endorsed by FCA US LLC. Chrysler, Dodge, Jeep, Ram, Mopar and SRT are registered trademarks of FCA US LLC.