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Drew
Dodge Dakota
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3/18/2002
20:35:46
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 Subject: 7.25 MPG and dropping HELP?!
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i've gone from 11MGP down to 7.25 MPG in 4 months...... Can anyone suggest anything to help bring this back up? , and it seems to be dropping about .05 MPG every fillup.....and at $45/Fillup it's getting tight...
Thanks.
'98 3.9L CC, Hawk Cap, K&N Drop in.
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better n u
Dodge Dakota
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3/18/2002
20:51:24
|  RE: 7.25 MPG and dropping HELP?!
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Pinch the fuel line to restrict the amount of fuel to the motor, this should help. and or trade in truck for a chevy S-10 and live it up!
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CW
GenIII
3/18/2002
20:54:54
| RE: 7.25 MPG and dropping HELP?!
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Try new O2 sensors.
2001 4.7 5sp RC 3.92 LSD
Click on avatar for mods
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LI Blackdak
Dodge Dakota
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3/18/2002
22:25:57
|  RE: 7.25 MPG and dropping HELP?!
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two words "honda civic"
three words "get it fixed"
four words "I sure am usless)"
;-)
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oetkenjc
R/T
3/18/2002
22:39:53
| RE: 7.25 MPG and dropping HELP?!
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rofl... I have no suggestions... but that last post was pretty funny
jonathan
Best Run: .520rt, 2.138 60foot, 15.041secs @ 89.44mph
PCM, 160 degree Tstat, Nitto 450's, Darkfury's homemade SS Grill (www.chimptopia.com/pimptopia/grille.html)
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Drew
Dodge Dakota
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3/18/2002
23:20:47
| RE: 7.25 MPG and dropping HELP?!
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lol , LI Blackdak
I'm not From Quebec so a Civic is not verry fashionable.
I'm gona call the dealer tommorow and take her in for repairs... I was thinking New plugs, Wires, Distrib?
But thanks for your input all.. If ya all can think of something else i should check?
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Todd W
Dodge Dakota
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3/18/2002
23:25:28
| RE: 7.25 MPG and dropping HELP?!
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Well, if your taking it into the dealer to get it checked, I wouldn't try anything. They should diagnosis it for free, so they can tell you whats wrong. :0)
Sounds like an O2 sensor to me though..
Or... well, my truck did something similiar and started running -real- rich. Took it in and all they -said- they did was reset the computer. I'm not sure, but maybe. It was only at about 5000 miles then.
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Dakotaman
Dodge Dakota
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3/19/2002
00:35:22
| RE: 7.25 MPG and dropping HELP?!
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Man guys help the him out here! 11 miles per gallon sucks 3.9 should get 13-14 easily and thats blowing by an S 10 the ones that are still running that is. S10's are nice trucks if you consider a bumper an option! who needs a bumper when your not moving! Good luck take it to the dealer. The heartbreak of today's Chevolet the S10.
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Mike
Dodge Dakota
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3/19/2002
21:08:14
| RE: 7.25 MPG and dropping HELP?!
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Check your computer codes to see what faults the compter is reading. You can find those how to do this and what the codes mean here:
http://www.dakota-truck.net/CODES/codes.html
or from a factory service manual or the like.
My 93 3.9L went from 22 mpg to 10.5 mpg where it stayed for almost a year no matter what driving I did. Checked the codes, found out my oxygen sensor was stuck open and my MAP sensor needed replaced. As soon as I replaced the two sensor, my mpg jumped back up to where they used to be.
Good luck :)
Mike
www.geocities.com/geek_farm
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MJH
Dodge Dakota
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3/19/2002
22:14:21
| RE: 7.25 MPG and dropping HELP?!
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Does "P Done" mean that i am clear of problems???
Thanks
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Drew
Dodge Dakota
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3/19/2002
22:26:43
| RE: 7.25 MPG and dropping HELP?!
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Hey ,
Thanks for all your help so far,
I called the dealer and explained the issue with him, He says there would be no codes if they plugged it into the computer, and that he has no idea what "might" cause it... he didn't even suggest bringen her in... :( so i said ok fine,
I tried the thing from www.dakota-truck.net and it doesn't give me any codes ither, SO, I've so far replaced my plugs.
The wires & destrib will prolly be done aswell soon, I've dumped fuel system cleaner into the tank.. (not the cheap stuff) .
Any more suggestions? Could it be caused by my K&N drop in? I checked it and it is still really clean.
How much do O2 Sensers cost?
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Mike
Dodge Dakota
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3/19/2002
23:23:22
|  RE: 7.25 MPG and dropping HELP?!
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Drew,
Sorry, but your dealer doesn't know what the heck he is talking about or he's trying to blow you off. Do you have a major fuel leak, a blown gasket, and are all of your vacuum lines are disconnected?
How is your truck running aside from the pitiful mileage? Is there what appears to be black soot on the inside of the tip of your exhaust, or is the exhaust extra smokey compared to usual?
If you truck is otherwise running all right, then 90% likely you have a sensor problem. The DML trouble codes are for 92-96 trucks. There is probably a different way to access those codes since you have a 98. I'd recommend getting a Haynes manual or asking the dealer parts or service desk for you to look at the factory service manual specific to your year Dakota. In that book will be instruction to access any computer codes there might be. Every sensor that helps the computer control the fuel management has a code representing a possible problem. That means manifold pressure, air temperature, throttle position, and any of your multiple oxygen sensors.
NO, an air filter will not cause you to get 50% worse mpg. A free flowing air filter HELPS the engine run more efficiently, unless you are running around town constantly at wide open throttle (and I mean constantly).
The problem is your truck is using twice as much fuel as it should be. Make sure it is not leaking any gas. Otherwise, the gas has to be going into the combustion chamber and out the exhuast, probably partially unburnt because more than likely, your truck is rich. Reasons for this could be the comp. thinks the exhaust temperature is too low. Example of this in normal operation is when you start your truck in the morning and the computer automatically runs rich until the engine is at a normal operating temperature. Another possible reason is the computer thinks the vacuum in the intake manifold is somehow incorrect for the conditions.
A MAP sensor from Autozone should run you about $55. Same for an O2 sensor, but your truck does have more than one of them.
Sorry for the rant. I imagine you called your dealer around closing time. Even so, a lto of dealers even good ones, wont take a lot of their time to help you with a MPG problem or concern because these Magnum engines are notorious for poor gas mileage.
There is a small chance the computer will not have recorded any malfunctions in the sensors, but that doesnt mean the sensors are not malfunctionng. If you can't pull any codes, go ahead and replace the MAP sensor and see if that helps any. If it does, even if only 1 or 2 mpg, then change your )2 sensor. You can always return the MAP sensor if that doesnt solve the problem.
Sorry for such a long post, I hope it helps
Mike
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Drew
Dodge Dakota
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3/19/2002
23:42:08
| RE: 7.25 MPG and dropping HELP?!
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Mike,
Thanks for your novel ;)
I called my dealer at 9:00am yesterday AM,
I will get hold of my "normal" mechanic and just get him to replace those sensers for me...
Thanks again all.
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Phil G. Pasca
Dodge Dakota
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3/20/2002
12:37:59
| RE: 7.25 MPG and dropping HELP?!
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hey go to auto zone if theres one neer you. they plugged right up on my pcm for my 98 DAK and told exactly what was wrong. Very helpfull but best of all FREE.
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02XCDak
Dodge Dakota
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3/20/2002
14:55:40
| RE: 7.25 MPG and dropping HELP?!
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Quick side Q... but doesn't dumping tons of raw fuel down the exhaust really shorten the life of the cat-converter...? I had a problem on a previous auto with this and the cat got so plugged up it caused all kinds of expensive problems due to the added back pressure. An extreme case, I know... but a good reason to get it fixed as fast as possible.
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Drew
Dodge Dakota
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3/20/2002
21:44:17
| RE: 7.25 MPG and dropping HELP?!
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well new numbers are in, 6.9MPG..... :(
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Drew
Dodge Dakota
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3/20/2002
23:16:09
| RE: 7.25 MPG and dropping HELP?!
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Hey Guys,
Heres a thought,
I was reading the Old posts from the site and saw Someone say that after they installed the K&N drop in filter the mileage went WAY down, and that they had to reset the computer to fix this, Think this would help?
'98 cc 3.9, K&N Drop-in, Hawk Cap,
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kota on 20s
GenIII
3/20/2002
23:41:52
| RE: 7.25 MPG and dropping HELP?!
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i seriously doubt it. how is the power in the truck?
Eric, 98 5.2 5speed, K&N gen II, 50mm TB, 2bbl M-1, 1.7RR's, JBA ciramic headers, carsound cat, dumped gibson, and a lot more
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Drew
Dodge Dakota
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3/20/2002
23:45:28
| RE: 7.25 MPG and dropping HELP?!
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The power seems to be ok.
The only thing worng seemingly is the gas mialage... I looked in the exhaust for the black stuff, And everything looks Normal...
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Drew
Dodge Dakota
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3/22/2002
21:48:11
| RE: 7.25 MPG and dropping HELP?!
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Well,
I got a chance to get to the garage today,
Currently getten 5.7MPG by this time....
They hooked it up to the computer and Would ya look at that. There actually WAS something wrong :P
There was a section on the computer that supposidly Measures the Air/Fuel Ratio in the motor, Aparently the values are supposta be within -5 to +5 (anyone know what it's real name is?) well turns out when my motor first starts it's at +3 -> +4 for the cylinders, But as soon as the motor warms up it went right up to +12 and +16...... So they've done a "3 stage injector Power Purg" and they say this should fix it. I guess we will see...
Thanks for all your help.
An a side note, Does taking off the tailgate Help mileage?
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drunkace
Dodge Dakota
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3/23/2002
01:31:57
| RE: 7.25 MPG and dropping HELP?!
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I've heard this one before.....is someone taking gas out of your tank?
if not, maybe it's a leak or a bad injector???
I also agree that it cound be the o2 sensor....is your tail pipe black and smells like rotten eggs? that would mean too much fuel is being used...hope I can help,good luck....
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scat pack
GenIII
3/23/2002
10:21:31
| RE: 7.25 MPG and dropping HELP?!
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Removing tailgate should increase drag, but lowering it should help.
2K RC 4.7 4x4
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