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matt
Dodge Dakota
JOIN HERE
4/06/2007
22:50:12
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 Subject: gas mileage
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Message:
i have an 01 dakota 3.9 with 112k miles.. i currently average 12.8 mpg with mixed city and hwy miles and can get up to 15.9mpg with hwy only. i have replaced all my oxygen sensors recently. I replaced my spark plug wires about 40k ago and my plugs about 60k ago. i am looking at replacing my plugs again but will they alone help me get back to where it needs to be or what other options should i consider? and what kind of gas mileage should i be getting?
-thanks, matt-
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dakota49
Dodge Dakota
JOIN HERE
4/07/2007
16:13:04
|  RE: gas mileage
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Message:
Mat, there are a lot of things that can effect fuel mileage. The plugs alone may be good for about 1 mile per gallion, maybe more depending on how bad the ones you have now are. Other things to consider are, air filter and fuel pressure regulator. I was having problems with my fuel mileage changed the plugs and got 1 mile per gallion, still I was getting 18-19 mpg, now 16, after plug change. I kept checking my plugs and found it was running rich. I found I didn't have any vacuum at the hose going to my fuel pressure reg. So I hook a vacuum line directly from the intake manifold to the regulator. It made a big difference, in the way it runs, and I can't say yet that its going to get any better fuel mileage, I just hope so. Without vacuum the pressure reg. was operating in full throttle (no vacuum) mode all the time. That COULD account for the plugs being black all the time. And it can affect fuel mileage.
I hope this gives you something else to check.
Good luck
Bert
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J and J Auto
GenII
4/08/2007
03:08:37
| RE: gas mileage
IP: Logged
Message:
The vac regulators are not used on the newer
trucks
The pump is run tru a ballast resistor and relay
while cranking full volts from starter relay
At WOT wide open throttle full volts from o2
circuit
normal it will have around 40 45 psi under these
2 conditions the pressure will rise 8 to 10 psi
use good plugs the NGK V power
vac leak
o2 hope its not a bosch if so get it out and
go to ngk.com and get the right sensor
bad map
IAT or engine temp
these will all effect milage a few mpg
Larry
J&J Auto
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dakoat49
Dodge Dakota
JOIN HERE
4/08/2007
12:20:31
| RE: gas mileage
IP: Logged
Message:
Larry, I forgot to mention mine is an 88 I didn't realize the newer trucks used something different, thanks for the info.
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