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  #1  
Old 12-12-2009, 01:38 AM
Walkercolt Walkercolt is offline
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Unhappy Poor gas mileage with an '04 4.7L

In about the last 6 months, starting just before my 50,000 mile major service, the fuel economy on my '04 Club Cab 4.7L auto has been dropping. At the major service we did plugs and everything and more the book says, I had the injectors cleaned with the BG system. I had cleaned the K&N just before the service, and I use only 100% gasoline (or the mileage REALLY drops). I'm thinking maybe the "downstream" cat-con sensor may be going, keeping the mixture too rich. Dump a can of Berryman B-12 ChemTool in the tank, and the mileage improves, for that tankful. I'm not showing a code, my dealer checked the sensor's at the 50K service, but they are just pass/fail. The service writer thinks I have the right idea, but $100+ for sensors to test my theory seems a bit extream. I'll take guesses, wild-ideas, or Voo-Doo at this point. Oh, yes, I ran a couple of cans of Sea-Foam thru it with no apparent improvement. My in-gear idle has dropped from 600 RPM to just above 500 RPM and is slighty rough. Throttle-body cleaning time? Anyone know of a step-by-step pictorial or video on cleaning the 4.7 TB? (I know how to clean a 3.9 or 5.2 Magnum, but that's not much help).
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  #2  
Old 12-12-2009, 03:39 PM
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JVMopar JVMopar is offline
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What is your mileage? My dad's 02 gets 17-18.

The down stream O2 sensor doesn't control mixture. It's only there to monitor the converter efficiency. So replacing a downstream O2 is kinda pointless unless you get a converter efficiency code.

You also have to remember that this time of year fuel economy drops. There is more oxygen in air because the molecules are closer together. More oxygen = more fuel = less fuel economy. It also takes longer for it to reach opperating temperature. So your burning more fuel there too.

Just for comparison I went from 30-33 with my sundance to 25-28.
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Old 12-15-2009, 04:22 AM
Walkercolt Walkercolt is offline
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JV, according to the service manual at the dealership(on CD), we're both partly correct. If the down-stream O2 sensor doesn't get hot enough, it calls for a richer mixture to make the cat-con hotter. Usually, I get better mileage in the winter down here, because the gasoline formula is better (more "nose" or light ends). I'm down to 15 MPG in town (at best) and 17 coming back 103 miles from OKC no stops except for 2 toll-booths (that's usually a 22-23 MPG trip). I may be money ahead to keep adding Berryman B-12 to each tank. Oh, I found a very good step-by-step on the Dakota Forum on cleaning the 4.7L thottle body. Not much different than the Magnums really, so that's probably my next step right now. I wish I had my 391 Magnum stroker back in my '98!
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Old 12-24-2009, 04:29 AM
Walkercolt Walkercolt is offline
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Update: My thermostat is getting "lazy" so, after the blizzard that'll hit before Christmas, I'll change it out (Grrr...). But both me and a mechanic at the dealership are still eye-balling O2 sensors. As hard as they are to get-out in one piece to measure the exhaust tempature (the drop-dead test) it's pretty much replace 'em and see if it helps.
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Old 06-20-2013, 10:48 AM
cobraearl cobraearl is offline
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Quote:
Originally Posted by Walkercolt View Post
Update: My thermostat is getting "lazy" so, after the blizzard that'll hit before Christmas, I'll change it out (Grrr...). But both me and a mechanic at the dealership are still eye-balling O2 sensors. As hard as they are to get-out in one piece to measure the exhaust tempature (the drop-dead test) it's pretty much replace 'em and see if it helps.
did anything ever help???
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  #6  
Old 06-21-2013, 02:00 AM
Walkercolt Walkercolt is offline
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Saturday something will help alot! A new/used 2011 Hemi Ram. I test drove it in stop and go traffic for an hour and a half, and it's an early-build 5 speed auto mind you, and I averaged 17.4 MPG for 45-odd miles. My Dakota driving on cruise down the turnpike at 75 on premium 100% gas didn't get that. I'm getting 13.4-15 MPG in town with the 4.7L and the REAL mechanic at my dealer says I'm doing good with the emissions motor. The Ram Crew cab has 22K on it, it's a Big Horn Edition that was ordered, one owner, who I talked to, he traded for a 2500 Cummins less than 2 weeks ago, and I thought the truck was brand new when I pulled up beside it. Has everything but the DVD players in back, power pedals, leather (which is good with me), and power moon roof. It has the fixed moon roof. He spec'd it out hard-loaded. Front power buckets and bucket/bench rear just like my '74 Dart had. I'd rather have a mid-size pick-up with a V-8, but the only game is the Mitsubishi Raider and I'm in Tulsa, OK. and the nearest dealer is Dallas. It uses the Dodge 4.7L 300HP motor and gets lousy mileage too. My Mexican neighbor has a brand new Mexican Dakota, styled like the new Durango, with a 4 cylinder Cummins turbo diesel (185 HP/300+ ft/lbs) four door, 6'4" bed (longer wheelbase) 8 speed that gets mid 20's in town, up to mid 30's hiway. Huge seller in South, Central America and Mexico. Quieter than a 4.7L gas Dakota too. No screens or cat-cons either. Habenjero Red. (Almost Hemi Red)

Dear Chrysler: Bring back the Dakota. Saw two cylinders off the 5.7L Hemi and build a 4.0L V-6 Hemi coupled to the new 8 speed automatic transmission with PUSHBUTTON SHIFT. 300HP/350 ft/lbs. torque in a 4100 lb. Club Cab mid-size pick-up (curb weight) that could tow boats and decent RV trailers would shut down the imports, the Ranger and Colorado. We quit buying Dak's when they got worse fuel economy than Rams. I'm dumb, but I bet I can make a V-6 Hemi in my garage that'll stomp the 4.7L into the ground in every way...I'd use a counter rotating balancer shaft swinging inside the crank. Learned that from Enzio Ferrari...and the Corvair!
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Old 06-21-2013, 07:18 AM
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My Dad sold his Dakota and bought a 2013 Ram with the 4.7L, 4x4, crew cab, 6.5 box. He drove it up here the other weekend and the tell tale on the dash said 23mpg.
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Old 06-22-2013, 12:59 AM
Walkercolt Walkercolt is offline
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The Hemi's get better fuel economy than the 4.7L Flex-Fuels even according to the EPA specs. I wish this 2011 was a "late-build" with the six speed OD, but 50% better gas mileage with a Ram and me driving about 850 miles a month (and I'm disabled) will cut my gas bill enough to make a real difference. This is burning 100% 87 octane regular gas, not even premium 100% gas. I have seen fuel payment slips and mileage numbers showing guys with Rams using the latter, getting 28-30 MPG highway at 75-78 MPH, Dallas-Denver, KC-San Antonio, etc. Too much like my '98 5.2L Magnum I had put a Hughes 391 stroker crank into, for three glorious weeks, before it was totaled as well as my back, by a drunk. I talked VERY seriously to the guy in Tejas about cramming a Hemi into my Dakota, but I'd also need a 5 or 6 speed auto and computer(s). Even with good salvage parts, it's not a cheap conversion. $5-8 grand depending on the body style. I'm nearly 60, and the Ram should be the last vehicle I'll ever buy.
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Old 06-25-2013, 08:12 PM
cobraearl cobraearl is offline
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Quote:
Originally Posted by Walkercolt View Post
Saturday something will help alot! A new/used 2011 Hemi Ram. I test drove it in stop and go traffic for an hour and a half, and it's an early-build 5 speed auto mind you, and I averaged 17.4 MPG for 45-odd miles. My Dakota driving on cruise down the turnpike at 75 on premium 100% gas didn't get that. I'm getting 13.4-15 MPG in town with the 4.7L and the REAL mechanic at my dealer says I'm doing good with the emissions motor. The Ram Crew cab has 22K on it, it's a Big Horn Edition that was ordered, one owner, who I talked to, he traded for a 2500 Cummins less than 2 weeks ago, and I thought the truck was brand new when I pulled up beside it. Has everything but the DVD players in back, power pedals, leather (which is good with me), and power moon roof. It has the fixed moon roof. He spec'd it out hard-loaded. Front power buckets and bucket/bench rear just like my '74 Dart had. I'd rather have a mid-size pick-up with a V-8, but the only game is the Mitsubishi Raider and I'm in Tulsa, OK. and the nearest dealer is Dallas. It uses the Dodge 4.7L 300HP motor and gets lousy mileage too. My Mexican neighbor has a brand new Mexican Dakota, styled like the new Durango, with a 4 cylinder Cummins turbo diesel (185 HP/300+ ft/lbs) four door, 6'4" bed (longer wheelbase) 8 speed that gets mid 20's in town, up to mid 30's hiway. Huge seller in South, Central America and Mexico. Quieter than a 4.7L gas Dakota too. No screens or cat-cons either. Habenjero Red. (Almost Hemi Red)

Dear Chrysler: Bring back the Dakota. Saw two cylinders off the 5.7L Hemi and build a 4.0L V-6 Hemi coupled to the new 8 speed automatic transmission with PUSHBUTTON SHIFT. 300HP/350 ft/lbs. torque in a 4100 lb. Club Cab mid-size pick-up (curb weight) that could tow boats and decent RV trailers would shut down the imports, the Ranger and Colorado. We quit buying Dak's when they got worse fuel economy than Rams. I'm dumb, but I bet I can make a V-6 Hemi in my garage that'll stomp the 4.7L into the ground in every way...I'd use a counter rotating balancer shaft swinging inside the crank. Learned that from Enzio Ferrari...and the Corvair!
IVE ALWAYS thought they should build a Diesel Dakota... Glad to here Mexico at least has one. I thought Mitubitzi invented the counter shaft. in the 80's.
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  #10  
Old 06-26-2013, 12:27 AM
Walkercolt Walkercolt is offline
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If you really want to be accurate about it, James Watt did this on steam engines first, then Renault used it on their monster 12 liter single cylinder 1904-ish LeMans engine (the fewer the cylinders, the larger the displacement engine you could have) and the Duryea Bros. used one on their 1898 52* V-8 engines to reduce the rocking couple. The 52* Vee was required by the German Bosche Magneto that made a spark every 224* of rotation. Glenn Curtiss was one of the earliest makers of a 180/360* magneto which made 45 and 90* Vees possible. The Bosche Mag worked fine for inline engines, as you just changed the gearing to make the timing work out. There's no gearing that will make 52* go into 45* or 90*. Henry Ford got around the high voltage magneto with his high tension spark coil, while Georges Stratton was perfecting his flywheel magneto/high tension spark coil. (The Wright Bros. used a version of this.) Ford's system was a take-off of the German Kettering ignition, but simplified. There's not ANYTHING that hasn't been done to internal combustion engines; most of it during the 1930's for aero engines. Just read the "Proceedings of the SAE" from say 1931-1938. The "Bible" of gasoline engines is Sir Harry Ricardo's "High Speed Internal Combustion Engines" (that meant over 550 RPM) published in 1922 Oxford Press London. Very soon, motorcycle and outboards will have his "sleeve valve" engines just like the last piston engined aircraft did (the Constellation, the DC-6, the Boeing Stratocrusier, the B-36 and B-50), then it will filter down to autos for HP/liter therefore HP/pound of engine plus the enormous torque.

The 2011 Ram Quad Cab Hemi 545 ERFE is getting 16.8 MPG in-town on reg. no ethanol vs: 13.5-14.8 with the Dakota Cub Cab on the same fuel, 4.7 L 45RFE . 395 HP vs: 230 HP. Almost a ton more curb weight. What's wrong here? No, I don't put my foot in the Hemi like I do in the 4.7 or I'd be doing 90MPH in a city block from a stop light. (Ask me... when I killed the Camero yesterday...thank goodness for an Auburn!) I cornered a factory rep teaching the salesmen about the new Darts, and asked about getting Dakotas back, especially with either a V-6 Hemi or the new V-6 that's in the Ram. Politics won't let it happen. Too much performance. Only because the Ram is over 5500 GVRW will the Fed's put up with the Hemi in it. The Hemi Challengers and Chargers are "specialty vehicles" that don't sell enough units to have to meet NHTSA test standards or all EPA standards. Just like 1994 was the year for the fastest top speed production motorcycles and always will be. Big Mommy doesn't want us to be able to go too fast and hurt ourselves.
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