4.7 more power and better gas mileage
 

I love to get 4.7 more power and better gas mileage out of my 2004 4dr cab 4wd

We all would Kevin but, your quad cab is one heavy truck so it'll never do great on mileage. A lot depends upon your left foot.

What gears do you have? What are you getting for mileage? O2 sensors do get lazy as they age, as does the MAP sensor.

You can get a flash.

There really isn't anything, the 4.7 has almost no aftermarket support. But some basics that don't hurt your fuel economy and boost your power. Exhaust, fastman tb and good spark plugs (nothing exotic, but good copper ones). Now you can also do a cold air intake but I suggest you kind of ignore it, I mean it can help but not really. Build your own if you really want one.

Other things that can benefit you is a 5-speed tranny and 3.92 gears. The 5 speed auto will do 70 mph at ~2000 rpm with those gears, the 5 speed manual I think is closer to 2,100 at 70. The manual transmission is hands down the best, if you have the choice get it.

As for the o2 sensors and map, he is right, they do cause problems. Check them on occasion and from what I've heard sometimes it is wiser to replace it when you think it is failing versus you get a code say they have.

Yeah, there really isn't a lot you can do, but let us know what you're getting for gas mileage now. That way we can tell if you're getting what you should be or not. The truck won't be great on gas but the 4.7 has some decent power from the factory compared to other trucks in its class, its not a dog by any means.

I used to pretty regularly get about 17.5 mpg with mine, which is a 5 speed w/ 3:55's.

I have pos rear end with 3.92 gears and the over drive auto.
It never had good mileage. On the highway with nothing on the ball. it would only get about 15 mpg. Put on a 6 x 12 trailer it goes to 10 mpg.
Starts good and runs fine.

I'm about 12mpg city and about 22mpg highway.

For a truck.. eh.

I got my Fusion and it worked out because of the cost. I either pay $400 a month in fuel for the Durango. Or I pay $250 a month for my car and another $150 in fuel. Either way I'm still paying $400 but at least I'm getting something for my money.

Maybe this applies to your situation (I also kept my Durango because..well, it's a "truck")

You get 22mpg on the highway with your Durango!? I could do 65 all day with my Dakota which has 3:55s and only get 19-20. I've never touched 22. The best I've ever got was 20.5 and that was on roads that were 55mph for a long time.

Yeah. That's a 3.55 rear with 32.5" tires @70 mph.
Before the Jeep TCM swap I got about 19 @ 70 mph
This is with the AC system off as I only drive the durango for road trips which I usually take a month off in December for. Two years ago was to Colorado, 1,400 miles. Last year to Cali, 2,100 miles.

The trip computer is never more than .5 mpg off from fuel pump numbers.

What did the Jeep TCM swap do to help?

Turned my 4 speed auto into a 5 speed auto.

Oh that's right. I've heard of guys doing that. I have a manual though, so I find it hard to believe your 5 speed automatic Durango should get better gas mileage than my 5 speed manual Dakota that weighs probably 500+ lbs less.

People often assume weight has a direct effect on momentum when in fact this is not the case.

There are lots of variables that can cause one said vehicle to perform better than another.

I'd be intrigued to see the gearing ratios between the automatic and the manual.

You're right, and actually I could see the weight HELPING under a constant 65-70 mph trip, so long as the road is completely flat (or downhill). I never drive on roads that are flat. I live in far upstate NY and previously in Vermont where there are a lot of mountains.

As far as gear ratio, I'm at exactly 2000 rpm @ 70 mph, 5th gear obviously.

Interesting, I'm at 1,800 @ 70
Attachment 40645

and 1,450 @ 60
Attachment 40646

I guess that could be the difference. Although I'd actually rather have the 3:92 gear ratio so I could be around 2200 rpm at 70 due to the elevation changes on instates 87 and 89 that I drive frequently. There are a few hills I need to drop down to 4th gear on.

And I'm in no way complaining about the gas mileage. Just find it interesting the Durango does better than my Dakota.

If I could find my post from a while ago I actually did work and gave the rpms for all the gears and ratio for our transmissions manual/auto and 3.55/3.92/and a 4.10 estimate. Give me bit and I'll try to repost it here

I have the 5 speed auto with 3.55s and at 120 km/h it's 1900 rpm.

Okay unfortunately I can't find it easily, with as many posts as I have I don't have the patience.

Anyways, I have done it once I'll do it again:

Automatic transmissions with dodge are often the same or similar construction 45RFE is actually a 545RFE, the gearing numbers are the same. The 4(2,4,6)RE are differentish, I'll put those in after the 545RFE so scroll farther down for those. For those bastards (I hate you out of jealousy) who have a manual 5 speed tranny NV4500, I've made you scroll past the automatics.

(5)45RFE

1st- 3.00
2nd- 1.67 (With the 545RFE the kick down planetary gearing is 1.50)
3rd- 1.00
4th- 0.75
5th- 0.68 (545RFE's 5th gear, when your TCM allows it)
Reverse- 3.00

4(2,4)RE transmissions are the same but able to handle different amounts of power

1st- 2.74
2nd- 1.54
3rd- 1.00
4th- 0.69
Reverse- 2.21

Those of us gifted with the 5.9 V8 get the special 46RE

1st- 2.45
2nd- 1.45
3rd- 1.00
4th- 0.69
Reverse- 2.35

Now for the bastards with a stick or the NV4500

1st- 5.61
2nd- 3.04
3rd- 1.67
4th- 1.00
5th- 0.73
Reverse- 5.04

RPM numbers
Now I only have rpm numbers for the 545RFE transmission and axle ratios, your number should be very close or around these numbers if you're tires aren't stock.

3.55:1 @ 70
4th- 2,050
5th- 1,800

3.55:1 @ 60
4th- 1,850
5th- 1,500

3.92:1 @ 70
4th- 2,200
5th- 2,000

3.92:1 @ 60
4th- 2,000
5th- 1,750

For those who are curious 3.55:1 ratios with a automatic 5th gear, 2000 rpms @ 77 mph. Oh the engine loves that, it'll go up hills and not change.

For some of us not great with numbers, I've type a paragraph or two. Traditionally dodge truck/suvs 4 and 5 speed automatic transmissions, have 3 normal gears and 4 & 5th are overdrive gears. The automatics have the lower normal and overdrive gears which causes them to be more fuel efficient at cruising/highway speeds. The automatic transmissions do just that and are good for cruising around and long distance driving. But for the more truck stuff like towing and off-road they are in my opinion completely inadequate.
This is where the NV4500 manual transmission comes in. This 5 speed stick is perfect and at home in a truck, there can always be better things but this is great. Although the gearing is similar to the 545RFE, the NV4500 was created almost a decade before it. It is designed with GVWR of 14,500 lbs. so in Dakotas and Durangos it can is rated to handle 3,000 lbs more then what our GVWR rates us. The lower 1st gear gives significant advantages when towing, and with 5th gear isn't so low that you can still use overdrive while towing in some situations. Plus not to mention every advantage from engine braking, holding gears and intuitive shifting.

I'll edit this post with more information as I remember it or people ask for more. I hope it helps everyone.

Not sure if you meant an automatic w/ 5th gear is 2000 rpm at 77 mph, but my nv3500 is at 2000 rpm @ 70 mph. Stock tire size.

I fixed it, thank you, I spent all my patience typing that, I couldn't proofread it effectively.

No worries, I figured that was what you meant.

Just sold the truck today for 10k

Good luck Kevin!