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Old Jul 4, 2007 | 08:01 AM
  #31  
jwdenney2's Avatar
jwdenney2
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Mountain Pass
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The transmission was serviced 15k miles ago, and I changed tire size (from 235 to 245) about 8k miles ago.
 
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Old Jul 18, 2007 | 08:35 PM
  #32  
F350-6's Avatar
F350-6
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Joined: Mar 2007
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From: Texas
Did you ever figure out what the problem was? I just changed the fuel filter on my wifes 04 and was wondering if I need to look at the MAF sensor. She ran it into town and said it runs better but is still idles a little rough. Does yours idle rough?
 
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Old Jul 19, 2007 | 08:15 AM
  #33  
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jwdenney2
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I haven't yet. I started a new thread - I took a road trip and got excellent road mileage, so I know my problem is isolated to town. I was getting 16 mpg in town before, now I'm getting 13mpg, so I'm not sure what's up. I've tried all the simple stuff (easing around, different grades of gasoline, etc.).
 
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Old Jul 19, 2007 | 04:50 PM
  #34  
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24 Carat
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From: Just this side of nuts
Secret about 5.0 and fuel mileage. The oem ignition system sucks. 20% + of your gas goes out the tail pipe (actually burned up in the converter). A nice hot ingnition system add on will make your tailpipes a light grey.

Next step, shorty headers and stainless catback dual exhaust system.

3rd, K&N Airfilter.

Treat the fuel system twice a year wth BG 44K .

Bradford
 
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Old Jul 19, 2007 | 05:01 PM
  #35  
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last5oh_302
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Joined: Mar 2007
Posts: 1,063
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From: Ontario
Originally Posted by 24 Carat
Secret about 5.0 and fuel mileage. The oem ignition system sucks. 20% + of your gas goes out the tail pipe (actually burned up in the converter). A nice hot ingnition system add on will make your tailpipes a light grey.

Next step, shorty headers and stainless catback dual exhaust system.

3rd, K&N Airfilter.

Treat the fuel system twice a year wth BG 44K .

Bradford
The tailpipes on my Mustang are still black inside, and that's with an MSD 6AL ignition box and MSD coil. The car has been professionally taken care of with a custom dyno tuned chip as well.
It also has shorty Mac headers with X-pipe and Flowmster catback.

That's all perfectly normal.
 
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Old Jun 18, 2015 | 07:51 AM
  #36  
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24 Carat
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From: Just this side of nuts

Necro posting I know but where we are now:

1995 F-150 XLT Short Bed, Black / silver two tone Trailer Towing with 3.55's with a tall black capper.
180K and owned by me since 1998 with 16K, two owners.
5.0l stock innards with K&N, Tricked Jacob's Mileage Master ignition system incorporating the coil trigger from an older Jacob's unit so I have two complete ignition systems by swapping the coil wire location.
Shorty headers through the original Cat to a stainless catback exhaust. All ECU sensors are new as are water pump, thermostat and 14 lbs cap , 130 amp alt, MSD Super Conductor Ign wires with heat boots. 14 btdc and Motorcraft copper cores one step colder and side gapped to .55 . '98 explorer 4 hole injectors. I have taken this rig from 12 ->14 mpg to 18 city and 22+ highway.
 
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Old Jun 21, 2015 | 10:12 AM
  #37  
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Mohawkwoodman
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I had a toyota come in. He said were getting poor mileage i asked what you think you were getting. He said its only 26-28 mpg now. I almost laughed. He had low tires and ice build up I explained to him it was due to severe cold outside needing more fuel. I know that was off topic. But there are lots of things to check. No vacuum leaks?
 
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Old Jun 22, 2015 | 12:39 PM
  #38  
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Flatbed79F250
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From: Corry, PA
Originally Posted by dartguy699
make sure your exhaust is breathing ok (cat conv) a partially stopped up system can play havoc with mileage and you may or may not be able to tell by performance.
jim
How exactly does one go about checking cat flow?
 
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Old Jun 22, 2015 | 11:42 PM
  #39  
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Mohawkwoodman
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Water exiting tailpipe is a sign your cats may be working properly, but trucks have more then one. I like to take a good look at the o2 sensors, look at the long and short term fuel trims for both banks with a scan tool. But a Temperature laser tool is one way to check and compare your cats without a scan tool. Most of the time for engines that are pretty much bogged down under load pulling the upstream o2 then starting brings life back in it with a plugged cat.
a note for the federal emissions law you have to ask or fight for it most cases.
I dont know if this helps in your case sorry.
 
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Old Jun 23, 2015 | 06:19 AM
  #40  
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Flatbed79F250
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From: Corry, PA
That does help, i feel as if i have damaged cats and i say this because my truck was misfiring, and i heard that the cats on these trucks are very sensitive to that. i also hear a slight rattle coming from them at idle
 
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