3.9 V6 in a 2wd Dakota......
#642260
03/16/10 08:05 PM
03/16/10 08:05 PM
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Joined: May 2004
Posts: 4,920 Joplin, MO USA
Robbins
OP
master
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OP
master
Joined: May 2004
Posts: 4,920
Joplin, MO USA
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....is there ways to get it to get better gas mileage? I think that my 81 full size 2wd 1/2 ton with 318/OD833 gets better.
Moparlee
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Re: 3.9 V6 in a 2wd Dakota......
[Re: Robbins]
#642261
03/16/10 08:17 PM
03/16/10 08:17 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Trade it in.
I have found that old school V6's give you V8 mileage and 4 banger performance if you are lucky, lol.
Seriously, standard stuff, free flow exhaust, free flow air intake, good plugs, wires, cap/rotor, etc, are about it. There might be a computer "chip" that helps, but I know nothing about that. You might find that a turbo or supercharger would inprove your mileage, but I dunno.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: 3.9 V6 in a 2wd Dakota......
[Re: Supercuda]
#642262
03/16/10 08:53 PM
03/16/10 08:53 PM
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Joined: Oct 2003
Posts: 21,345 Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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nope. the 3.9L engine was good for um...nothing. as said, abysmal performance, power of a hopped up 4 cylinder, with the gas mileage of a larger V8.
make the truck lighter, swap the gear ratios around, maybe try a custom tune on the engine computer? I think the factory tune was pig rich on these things so that there was lots of gas to give the cat converters something to "chew on" and make them more efficient at their job. dunno if that's true or not though
**Photobucket sucks**
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Re: 3.9 V6 in a 2wd Dakota......
[Re: Mr.Yuck]
#642264
03/16/10 11:29 PM
03/16/10 11:29 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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My 2000 dak ex cab 4x4 3.9 with a topper is getting 3 mpg more than my 2000 durango with a 5.9
I had always heard the 3.9 was just as bad as the V8 but in this case it is not even close, I am happy with my truck, but like my title implys I am in the search for more. Today I put a cold air intake on it, I don't think it will help because the O2 sensor is going to make it dump more fuel in to make up for the extra air. One of thease days I will swap the O2 sensors so the primary one is reading the mix after the cat, that should fool it into thinking it is rich and lean it out a tad, I did this on a 5.2 ram truck and it worked great, the fuel trim went from adding 3% more fuel to takeing away 3% from the fuel map and gave me a consistant 1mpg. If your truck has the 518 trans the A-500 can help because it soaks up less of you already low HP and it can give you some more gear multiplication in 1st and 2nd gear. Another small gain can come from the 8.25 rear, it soaks up a little less power than the 9.25 that a lot of them came with. I pulled the belt driven fans off both rigs and that helps, both of my rigs have electric fans but I have pulled them from my 91 dak and it was fine with no fan unless I sat a long time in traffic, same with my 68 cuda but I have an electric fan on it to turn on in traffic.
I am trying to find info about a computer also so if anyone knows of one I want to know also.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 3.9 V6 in a 2wd Dakota......
[Re: POS Dakota]
#642269
03/17/10 11:07 AM
03/17/10 11:07 AM
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Joined: May 2005
Posts: 416 Franklin Co. Illinois
runinonmt
mopar
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mopar
Joined: May 2005
Posts: 416
Franklin Co. Illinois
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FWIW wife's auto. 02 quad cab gets 17-18. Performance sucks. It won't climb a hill on cruise without kickdown. My '93 club cab 5 Spd. got 18-24 and ran quite well, never needed to downshift for a hill on cruise or any other time. It was the main reason we bought the '02. Wife had to have auto trans. If you're underpowered the last thing you need is a trans that sucks power.
In sixty-five I was seventeen and running up one-o-one
I don't know where I'm running now, I'm just running on
Jackson Browne-Running On Empty
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Re: 3.9 V6 in a 2wd Dakota......
[Re: bigsbigelow]
#642271
03/17/10 12:50 PM
03/17/10 12:50 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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The180 t-stat will hurt MPG as the computer will dump more fuel since the CTS says the engine is not warmed up. Altering the TPS will not do anything because it zeros at whatever it was at when the engine is started. The V8 throttle body will not help bcause the O2 sensor will reset the map when it sees the extra air to keep the A/F ratiothe same. The bigger TB will allow you to make a tad more HP at WOT bcause the injector pulse is not going off the O2 at WOT, it will have a fixed injector pulse so it wll lean it out by letting in more air.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 3.9 V6 in a 2wd Dakota......
[Re: 65rbdodge]
#642273
03/17/10 05:27 PM
03/17/10 05:27 PM
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Joined: Aug 2003
Posts: 954 garnett kansas
rhad
super stock
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super stock
Joined: Aug 2003
Posts: 954
garnett kansas
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ive been driving a 2wd 3.9 v6 dakota since 95 ,tho the truck is a 92,it has a 3.92 rear axle,and gets better mileage than a similar dakota with a 3.55,3.9 v6,the problem is with the 3.55 rear its always downshifting on even the smallest hill on the road,while the 3.92 rarely downshifts,i have towed some really heavy loads with the 3.92 3.9 v6,and while its a little like the tail waggin the dog,it does do the job,i recently bought a 4x4 3.9 v6 with 3.55 axles,and im gonna change axles in it SOON, both have A500 trannys in them
Last edited by rhad; 03/17/10 05:29 PM.
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Re: 3.9 V6 in a 2wd Dakota......
[Re: rhad]
#642274
03/17/10 06:35 PM
03/17/10 06:35 PM
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Joined: May 2004
Posts: 4,920 Joplin, MO USA
Robbins
OP
master
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OP
master
Joined: May 2004
Posts: 4,920
Joplin, MO USA
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In these newer trucks and changing gears....does the trans still have the gear cog in the rear of the trans that can easily be changed out to help your speed-o-meter?
Thanks for everybody's feed back.
Moparlee
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Re: 3.9 V6 in a 2wd Dakota......
[Re: buildanother]
#642276
03/17/10 06:53 PM
03/17/10 06:53 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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until 96 they had the gear in the tailhousing like a 904 - 727 but in 96 they got an electronic speed sensor in the tail housing for the govenor and a speed sensor in/on the diff that reads the axle speed and gives you your MPH so if your truck is 96 or newer you can change gears and your computer will never be the wiser I wish you were closer with those 3.55 gears I would swap them for my 3.92s
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 3.9 V6 in a 2wd Dakota......
[Re: HotRodDave]
#642277
03/17/10 07:04 PM
03/17/10 07:04 PM
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Joined: Oct 2003
Posts: 21,345 Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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a 2003 Dakota SHOULD have the 3.7L v6, same engine family as the 4.7L they dumped the 3.9/5.2 in 01 I think it was? but kept the 5.9L in the R/Ts through 03, I don't think there were any 04 R/Ts
I think instead of TSP--Throttle position sensor, you meant CPS--crankshaft position sensor. the TPS resets every time the truck is started. the CPS is what the computer sets the timing off of. before I knew a lot about these trucks, I thought I'd fill the tank up with premium, and twist my distributor to get more timing and more power.
with the timing light on it and I was ready to go, twisted the dizzy, saw the timing advance, and about 3 seconds later, it went right back to where it was before!
but if you move the CPS, you can gain timing through the entire RPM range and the computer doesn't realize what's happened.
**Photobucket sucks**
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Re: 3.9 V6 in a 2wd Dakota......
[Re: 70Cuda383]
#642278
03/17/10 07:09 PM
03/17/10 07:09 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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Yes you can slot the CKS and get a couple degrees more timing but not much. Turning the distributer only changes the injector timing and has nothing to do with the ign timing. The only thing about turning the distributer is the rotor and cap terminal may not line up properly when the coil fires.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 3.9 V6 in a 2wd Dakota......
[Re: HotRodDave]
#642279
03/17/10 08:10 PM
03/17/10 08:10 PM
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Joined: May 2004
Posts: 4,920 Joplin, MO USA
Robbins
OP
master
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OP
master
Joined: May 2004
Posts: 4,920
Joplin, MO USA
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It's a 2002 SXT club cab 2wd with an 8 1/4 or 8 3/8 I guess now.....with the 500 style trans.
Moparlee
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