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05-11-2011, 10:54 AM
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#1
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Registered User
Join Date: Mar 2011
Location: SW Florida
Posts: 933
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What happened to my gas mi?
Maybe someone can help me out here. I have a 1990 HR 35' with a 454 and 3 speed trans. When I first bought it I got almost 10 mpg on the way home not towing anything and unloaded. I loaded it up (not much at all for 2 people), no fresh water and pull an open motorcycle trailer with my Harley on it (not over 1,200 lbs total.
On my first trip I averaged 8.5 mpg. On my second trip I got 7.6 mpg and then had the motor tuned up with new plugs, wires, dist. cap, rotor, and the injectors cleaned. My 3ed trip I averaged 7.1 mpg and now my 4th trip I only got 6.4 mpg.... All 4 trips were here in Fl. where it's flat and the weather conditions and wind were about the same. What could be going on? I always do 55 - 62 so that's not it. I'm afraid to take it back out and see 5.5 mpg.....
Thanks for any replies.
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05-11-2011, 01:24 PM
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#2
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Moderator Emeritus
Winnebago Owners Club Workhorse Chassis Owner Coastal Campers Carolina Campers
Join Date: Jan 2000
Location: Conway, SC
Posts: 23,641
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On my 2003 machine my MPGs began to tank when I developed a bad O2 sensor. Changed both! Not sure if this would help you at all.
__________________
03 Adventurer 38G, Workhorse W22
F&R Track Bars, Safety+ , Ultrapower, Taylor Extremes, SGII
TST 507, Blue Ox, SMI, Koni FSD, CrossFire
RV/MH Hall of Fame - Lifetime Member
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05-11-2011, 02:07 PM
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#3
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Senior Member
Damon Owners Club Workhorse Chassis Owner
Join Date: Mar 2009
Posts: 24,024
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Try a wash and wax.. In another thead someone tells me that the improvement in MPG I got is a bit more than he believes... But .. Well, try it.
If nothing else it keeps the rig looking better so it is time and effort well invested
But you might be surprised at the MPG change too.. I was.
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Home is where I park it!
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05-11-2011, 02:19 PM
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#4
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Senior Member
National RV Owners Club Nor'easters Club
Join Date: Jul 2008
Location: Pawtucket, Rhode Island
Posts: 225
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Could it be the ethanol in the fuel?
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05-11-2011, 03:26 PM
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#5
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Senior Member
Workhorse Chassis Owner
Join Date: Dec 2006
Location: La Quinta California
Posts: 523
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Quote:
Originally Posted by tims52ford
Could it be the ethanol in the fuel?
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Summer blend fuels will also drop fuel mileage..
Jim
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05-11-2011, 06:21 PM
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#6
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Senior Member
Workhorse Chassis Owner Entegra Owners Club
Join Date: Dec 2004
Location: UT/AZ
Posts: 1,417
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With my 1989 34 ft Bounder w/454 I got about 7mpg towing or not towing. With my 1990 34 ft. Pace Arrow w/454, I got between 5 and 6 mpg towing or not towing.
FWIW.
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Pat & Denise
2016 Entegra Aspire RBQ
18 Silverado
FMCA 212171
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05-11-2011, 07:04 PM
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#7
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Senior Member
Fleetwood Owners Club
Join Date: Sep 2010
Posts: 272
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Quote:
Originally Posted by tims52ford
Could it be the ethanol in the fuel?
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I agree!
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05-11-2011, 07:44 PM
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#8
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Registered User
Join Date: Mar 2011
Location: SW Florida
Posts: 933
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Quote:
Originally Posted by Dirtbuster
I agree!
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Thanks, never thought about the O2 sensor or the summer fuel. I'll have the sensor checked out. What's the difference in "summer fuel"? Here in Florida it's always summer....
I also washed and waxed the damn thing twice since I got it with all these love bugs.
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05-11-2011, 08:04 PM
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#9
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Senior Member
Workhorse Chassis Owner Entegra Owners Club
Join Date: Dec 2004
Location: UT/AZ
Posts: 1,417
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on the 454 left side exhaust, driver side, about 3 ft from the exhaust manifold, before the left and right pipe y's into a single pipe, you may have a heat valve in the exhaust pipe that can stick closed. It's closed when engine is cold and opens on warm up. If it does not open your engine can't breath properly out the left side. Symptom may be an exhaust popping sound when passing like a Jersey Barrier on the exhaust pipe side of the vehicle. Just a thought.
Pat
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Pat & Denise
2016 Entegra Aspire RBQ
18 Silverado
FMCA 212171
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05-12-2011, 11:40 AM
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#10
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Member
Join Date: Oct 2002
Location: Brownsville Tx. 78526
Posts: 92
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I had this engine set-up. 1983 Monaco. I got 6.5 to 7.5 average. And that's the truth.
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Ron
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05-12-2011, 12:26 PM
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#11
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Senior Member
Join Date: Jun 2010
Location: Upstate New York
Posts: 3,722
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Ethanol (10% or more) will hurt your gas mileage - and with some vehicles - significantly. My F350 - about 2 mpg in local driving. Gasoline has ~115,000Btu per gallon, ethanol is ~76,000 Btu per gallon. That means you will be getting 1.5% or poorer gas mileage at a minimum.
__________________
Dave W
2011 Ford F250 6.7 Lariat CCLB, Gone but not forgotten
2014 Montana High Country 343RL (sold it!)
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05-12-2011, 01:42 PM
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#12
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Member
Join Date: Oct 2002
Location: Brownsville Tx. 78526
Posts: 92
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Dave, With your figures, it seems it would be
a 34% drop in effic hiency.
76000/115000=64%
My mileage has dropped 1 mile per gallon,which is about 13%
__________________
Ron
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05-12-2011, 01:46 PM
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#13
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Senior Member
Join Date: Jun 2010
Location: Upstate New York
Posts: 3,722
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Quote:
Originally Posted by ronmc
Dave, With your figures, it seems it would be
a 34% drop in efficiency.
76000/115000=64%
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Ron, those are not mine but well published numbers by many sources. And remember, it's only 10% of the total (100%)
__________________
Dave W
2011 Ford F250 6.7 Lariat CCLB, Gone but not forgotten
2014 Montana High Country 343RL (sold it!)
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05-12-2011, 01:59 PM
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#14
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Registered User
Join Date: Mar 2011
Location: SW Florida
Posts: 933
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Quote:
Originally Posted by FreshAir
on the 454 left side exhaust, driver side, about 3 ft from the exhaust manifold, before the left and right pipe y's into a single pipe, you may have a heat valve in the exhaust pipe that can stick closed. It's closed when engine is cold and opens on warm up. If it does not open your engine can't breath properly out the left side. Symptom may be an exhaust popping sound when passing like a Jersey Barrier on the exhaust pipe side of the vehicle. Just a thought.
Pat
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Thanks, that's on my list to check too.
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