Mileage sucks
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Low ATF will reduce fuel economy. The trans maybe electronically controlled but it still operates off the principal of hydraulics. If the fluid is low, the torque converter will tend to slip more, the lubrication quality will be reduced, creating slightly more drag, etc. Even being a 1/2 qt low will make a difference.
If you changed out all the fluids, just make sure the level is correct with the trans in neutral and engine running when you check the level.
Other things to check, make sure none of the brake calipers are sticking, transfer case ATF level is at the hole, replace the O2 sensor.
BTW what quality of gas are you buying? These days, ethanol is mixed in with gas and it doesn't have the same "power" of gas. The energy density of ethanol is less than gas meaning that it takes more ethanol/gas to do the same amount of work as pure gasoline. It shows as reduced fuel economy. Ethanol also absorbs water like crazy and it also causes reduced economy and a slight loss of power.
If you have access to ethanol free gas in your area, run a couple of tanks thru and see if it makes a difference. (I know with mine it did)
Finally driving style. I don't know how you are driving, but when gas went up to $4 in my area a few years ago, I applied some of the techniques found at hyper miles and got up to 20 mpg. This was with a lifted 4x4 Dakota on 32s and powered by a 318.
Ed
Transmission ATF is good, Brakes are good, Tcase has new ATF is good, gas is regular Shell bronze (87), driving style is not aggressive but not Grandma Sunday either.
Been doing a bunch of reading, couple of ideas:
- The O2 sensor(s), likely original and the truck has 185,000 on it. Where is the sensor located, how many are there, are they all the same #, cost each?
- Viscous fan clutch, quite certain it is operating properly. I will pay some close attention to it so see that it is engaging and disengaging appropriately so is not hogging power/economy
- Engine temperature. The gauge is steady, runs at about 1/3rd of gauge. No number indicates. In my experience, warmer runs better, cleaner, and leaner improved mileage. Am looking into higher temperature thermostat options (if any)
Any specific guidance on the O2 sensor would be helpful.
I will update periodically with results as I try a few things noted.
Been doing a bunch of reading, couple of ideas:
- The O2 sensor(s), likely original and the truck has 185,000 on it. Where is the sensor located, how many are there, are they all the same #, cost each?
- Viscous fan clutch, quite certain it is operating properly. I will pay some close attention to it so see that it is engaging and disengaging appropriately so is not hogging power/economy
- Engine temperature. The gauge is steady, runs at about 1/3rd of gauge. No number indicates. In my experience, warmer runs better, cleaner, and leaner improved mileage. Am looking into higher temperature thermostat options (if any)
Any specific guidance on the O2 sensor would be helpful.
I will update periodically with results as I try a few things noted.
You have 2 cats, 1 on each side just below your exhaust manifolds. Each cat has 2 O2 sensors, 1 before and 1 after the cat.
Do yourself a favor and get this OBDII bluetooth adapter ([ame]https://www.amazon.com/dp/B014mv03ky/ref=cm[/ame]), and then download an app called "torque" on your phone. You will be able to monitor your o2 sensors with this app, it will display your ACTUAL coolant temperature, and a bazillion other things, right from your phone. It will also show you your current mileage, average mileage, all different things related to your mileage. You can check and clear codes, and just about anything else you could ever want. I have one in each of my vehicles.
Also, if you have an auxiliary electric fan, yank that mechanical fan out and dont look back. Ive been running just my electric fan on my dakota for many years, and even in 100+ degree heat, towing my boat up canyons, the fan is more than enough. Hell... the mechanical fan from my truck is actually what I use as my anchor for my boat!
Do yourself a favor and get this OBDII bluetooth adapter ([ame]https://www.amazon.com/dp/B014mv03ky/ref=cm[/ame]), and then download an app called "torque" on your phone. You will be able to monitor your o2 sensors with this app, it will display your ACTUAL coolant temperature, and a bazillion other things, right from your phone. It will also show you your current mileage, average mileage, all different things related to your mileage. You can check and clear codes, and just about anything else you could ever want. I have one in each of my vehicles.
Also, if you have an auxiliary electric fan, yank that mechanical fan out and dont look back. Ive been running just my electric fan on my dakota for many years, and even in 100+ degree heat, towing my boat up canyons, the fan is more than enough. Hell... the mechanical fan from my truck is actually what I use as my anchor for my boat!
Thank you Raz. Excellent info.
Great suggestion, I will put an OBD tool on the first todo list before spending on any sensors.
This truck has only the one fan, viscous/mechanical. No electronics on the fan. Personally I like that style. It just works. Only thing is to know how to check/test the viscous clutch and how to adjust its temperature if necessary.
Great suggestion, I will put an OBD tool on the first todo list before spending on any sensors.
This truck has only the one fan, viscous/mechanical. No electronics on the fan. Personally I like that style. It just works. Only thing is to know how to check/test the viscous clutch and how to adjust its temperature if necessary.
Two ways to know if your fan drags... When the engine is cold, pop the hood and spin it by hand. It should move pretty easily. Also when driving, if the fan is dragging, your truck will sound like an airplane trying to take off. Think of when its really hot, AC running, been stuck in traffic for a while, when you finally get on the gas you can definitely hear the fan trying to pull as much air as possible. Also, your acceleration would suck really bad. Its been my experience that you KNOW when your fan is a problem just from driving.
Minor Update, information only
I was looking into O2 sensors, IAT, MAP stuff today. Something that came apparent, but you have to be paying attention to catch it. On the O2 sensors, the part numbers for each of the four locations are NOT all the same or mirrored on this rig. The two upstream are the same, the two downstream are not the same to each other. I can imagine if the wrong one is put in place, although it seems to work it may actually mess up the fuel rations. FYI for anyone else looking at these:
These are what I determined for my 2005 Dakota 4.7 v8, yours may be different
Upstream Sensors: B1S1=Front Left, B2S1=Front Right
B1S1 B2S1 Mopar 56028998AB
B1S1 B2S1 Denso 234-4744
B1S1 B2S2 NTK 23556
Downstream Sensors: B1S2=Rear Left, B2S2=Rear Right
B1S2 Mopar 56028999AB
B2S2 Mopar 56028998AB
B1S2 Denso 234-4756
B2S2 Denso 234-4744
B1S2 NTK 23527
B2S2 NTK 23556
My next steps are to get under the truck to try to see any numbers to verify what is in which spot, then to figure out if my scan tool can read these sensors on this truck, to see which are working and what is not.
I was looking into O2 sensors, IAT, MAP stuff today. Something that came apparent, but you have to be paying attention to catch it. On the O2 sensors, the part numbers for each of the four locations are NOT all the same or mirrored on this rig. The two upstream are the same, the two downstream are not the same to each other. I can imagine if the wrong one is put in place, although it seems to work it may actually mess up the fuel rations. FYI for anyone else looking at these:
These are what I determined for my 2005 Dakota 4.7 v8, yours may be different
Upstream Sensors: B1S1=Front Left, B2S1=Front Right
B1S1 B2S1 Mopar 56028998AB
B1S1 B2S1 Denso 234-4744
B1S1 B2S2 NTK 23556
Downstream Sensors: B1S2=Rear Left, B2S2=Rear Right
B1S2 Mopar 56028999AB
B2S2 Mopar 56028998AB
B1S2 Denso 234-4756
B2S2 Denso 234-4744
B1S2 NTK 23527
B2S2 NTK 23556
My next steps are to get under the truck to try to see any numbers to verify what is in which spot, then to figure out if my scan tool can read these sensors on this truck, to see which are working and what is not.
Attached are a couple of screenshots from the Torque app I mentioned before. As you can see here, you can monitor each o2 sensor individually, check emission readiness as a whole, and whatever else you want. The screens are fully customizable so it can display all sorts of stuff.
This can help you diagnose any problem with o2 sensors in a heartbeat.
This can help you diagnose any problem with o2 sensors in a heartbeat.
Attachments
I have a DiabloSport inTune1000 that I've been using on my other trucks for tuning and as a basic scan tool. A while ago I tried it to see if I could use the tuner functions, there are no tuning for the Dakota in the inTune1000. However, I have not yet connected it to the Dakota to use just in scan tool mode.
I am assuming that if the Dakota puts out standard OBDII stuff, it is hopeful that should be able to see what's what using the equipment I have. Here is an inTune example from the Ram. I just have not had time yet to try it on the Dakota. Crossing my fingers that it will work!
That Torque app looks slick! It may have to be my next tool upgrade.
I am assuming that if the Dakota puts out standard OBDII stuff, it is hopeful that should be able to see what's what using the equipment I have. Here is an inTune example from the Ram. I just have not had time yet to try it on the Dakota. Crossing my fingers that it will work!
That Torque app looks slick! It may have to be my next tool upgrade.
Attachments
Truck running fine, guzzling gas as usual. Trying an experiment.
Pulled out the standard copper Champion Copper Plus, RC12MCC4 (439) spark plugs. They are fairly new, about 4500 miles on them. Plug condition is fine, typical low runtime plug appearances.
Put in standard copper NGK V-Power, ZFR5F-11, (2262) spark plugs. Immediate change in performance. Smoother and steadier idle. Noticeably more pep in mid range rpm ramping in moderate acceleration. Sensing that mpg is up after two tanks, qualifying with numbers TBA.
NOTE: Both are standard copper plugs. I have NO interest in trying platinum or iridium variants.
Observation; the Champions are what is spec'd on the sticker under the hood. I had put new ones in soon after purchasing the truck. The engine does run fine on them. The NGK are direct cross-ref replacement. However, the engine just generally seems to be much happier overall with the NGK V-power plugs; based on quick starts, a smoother idle, peppier midrange.
.... something you may consider trying as well. Not much cost, ~$40.
Pulled out the standard copper Champion Copper Plus, RC12MCC4 (439) spark plugs. They are fairly new, about 4500 miles on them. Plug condition is fine, typical low runtime plug appearances.
Put in standard copper NGK V-Power, ZFR5F-11, (2262) spark plugs. Immediate change in performance. Smoother and steadier idle. Noticeably more pep in mid range rpm ramping in moderate acceleration. Sensing that mpg is up after two tanks, qualifying with numbers TBA.
NOTE: Both are standard copper plugs. I have NO interest in trying platinum or iridium variants.
Observation; the Champions are what is spec'd on the sticker under the hood. I had put new ones in soon after purchasing the truck. The engine does run fine on them. The NGK are direct cross-ref replacement. However, the engine just generally seems to be much happier overall with the NGK V-power plugs; based on quick starts, a smoother idle, peppier midrange.
.... something you may consider trying as well. Not much cost, ~$40.
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This is why my quad-manual '06 has 225(less resistance than OEM) tires properly inflated cold and the K&N complete intake kit and aftermarket oil and trans radiators.. Drum brakes also adjusted to free spin.
I'm no expert though and I'm usually pulling a 16' 3k lb camper or 300lb motorcycle.. Not sure what else on an ECM injector system can cause it besides maybe tranny problems..
I'm no expert though and I'm usually pulling a 16' 3k lb camper or 300lb motorcycle.. Not sure what else on an ECM injector system can cause it besides maybe tranny problems..
It has been awhile. Update. Truck runs great. Awesome ride. Mileage still SUCKS!!!!!
Latest has been hookup of a BlueDriver obd reader which enables me to read fuel trims, oxygen sensors, engine load, temperatures, etc etc. For all intents, the numbers putting out on the live data charts are beautiful, right down the middle in ranges expected. Buttt .... the fuel tank gauge continues to fall like a rock.
I have come to accept and expect that this is just the way it is with the Dakota.
My next runabout is going to be full electric!
Latest has been hookup of a BlueDriver obd reader which enables me to read fuel trims, oxygen sensors, engine load, temperatures, etc etc. For all intents, the numbers putting out on the live data charts are beautiful, right down the middle in ranges expected. Buttt .... the fuel tank gauge continues to fall like a rock.
I have come to accept and expect that this is just the way it is with the Dakota.
My next runabout is going to be full electric!
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