2007 WK CRD "Not what I expected" Gas Mileage

[pixelcodex]

A bit of background info first: I have always owned cars, but I have been looking for a truck to use as a family vacation vehicle and to haul my motorcycle. I finally bought an 07 WK 3.0 CRD Limited 4x4 with ~124K miles about a month ago. I had researched both WK and XK with the 5.7 HEMI and — from what I had read — it was close to impossible to get decent MPG. Hence, when I came across the turbodiesel, I thought I could get the best of both worlds with great torque and decent MPG.

When I first got it, the computer showed about a 17 MPG average, but I did not know of the previous owner's driving habits and thought for sure I could do better. Well, the average declined ever since until it went below 15 recently. No matter what the claimed service history of the vehicle is, I knew when I got it I would need to do injector cleaner, filters and oils (engine and tray) service to get a baseline (which I did), and thought it would improve after. It did to a certain extent, but it does not climb too far past 15.3 or so. All along i have been monitoring things with a Scan Gauge II hooked up to get real time readings, and try to find sweet spots for the engine. I have been driving it different ways: first accelerating very gradually from a standstill. I then tried to test this theory that my slow acceleration could be forcing the engine a bit (with the turbo not spooling much) therefore affecting gas mileage negatively. So I tested — as I thought the initial torque of the engine would make a difference — accelerating it "semi hard" to around 40-50 and then letting the gear box get to 5th. Both methods yielded about the same average. Still get about 15 mixed, which is a lot worse than I think it should be doing.

Now the questions:

Besides filters and regular maintenance, what other problem areas should I look for in the diesel to get the original gas mileage back? At least something close to it anyway.

I have also been looking at lifts and general mods that can be done. From people's experience, how much does that affect MPG negatively? I almost wish there was a guide of sorts: I.e. Lift = -1,2 MPG, skidplates = -2 MPG, roof rack (I want a full size one to have a tent) = -2 MPG, etc. You get the idea. Even though there probably is no such guide, I am sure I can get a general guideline from people who have done the mods.

Any other general advice on getting better MPG out of this monster?

I look forward to the responses, thanks.

 

[SSF556]

Hello and welcome to a great platform and engine.....this 15.3mpg is city, mix or highway? Winter blend is out there and it does affect fuel economy.

The other issue could be the Diesel Particulate Filter (DPF) could be full. Unfortunately there is real no way to tell if it is full of ash.....and to replace one is about $2000 if not more.

I would try to take a road trip strictly highway and hand calculate your numbers...the EVIC which displays fuel economy is know to be off.

Did you put in a new air filter????




I have a 2008 CRD 4x4 with 67,000 miles. Around town I see 15-17 mpg......

I just took a road trip with my wife and dog, camping supplies and about 100 pounds on the roof (OzTent and Thule Car Top Carrier) and I saw 21mpg.

In my experience I do not see much difference in driving 65 or 75....fuel economy is generally the same.

I also have the full matrix system up front...see attached pic.

 

[Overlandexpeditionspecial]

In general, diesels tend to respond pretty well to programmers, that might be an option for you. I have a Superchips on my Wrangler, and the most valuable function I have found on it, is the ability to adjust shifting points, so you could optimize it for the terrain in your area; hilly, flat, whatever.

There is a generic ratio for MPG, I think it was for every 100 pounds you lose you can gain 1 mpg, so the opposite could be true. But racks and lifts, anything that creates more drag will be detrimental to your cause.

Slowing down is one of the most efficient increases in mileage of Jeeps, on highway trips I can gain or lose 3 mpg between doing 65 mph or 75 mph, 55 is even better but just depends on how fast you want to get there. (scootr29 posted while I wrote, so he should have a better idea on the mileage drag on WK than me)

 

[pixelcodex]

Hello and welcome to a great platform and engine.....this 15.3mpg is city, mix or highway? Winter blend is out there and it does affect fuel economy.

15.3 mixed, but mostly city. But even yesterday I was on the highway monitoring the SGII and could not find a sweet spot for optimum mpg. Oddly, I did notice what you said: 65 or 75 does not seem to make much difference.

The other issue could be the Diesel Particulate Filter (DPF) could be full. Unfortunately there is real no way to tell if it is full of ash.....and to replace one is about $2000 if not more.

I thought about the DPF, though had found no way of checking, you confirmed. I read about "DFP delete" through programming and hallowing it out. Not sure that would be a good option.

I would try to take a road trip strictly highway and hand calculate your numbers...the EVIC which displays fuel economy is know to be off.

Off the first full tank of diesel I got 16.2 average hand calculated. Again, thought I would do better.

Did you put in a new air filter????

Yes, air, fuel, and engine and tranny oil.

I have a 2008 CRD 4x4 with 67,000 miles. Around town I see 15-17 mpg......

Nice, mine is silver as well.

I just took a road trip with my wife and dog, camping supplies and about 100 pounds on the roof (OzTent and Thule Car Top Carrier) and I saw 21mpg.

That is the stuff I want to hear. I do not want to average 15 on the highway for longer trips...

 

[pixelcodex]

In general, diesels tend to respond pretty well to programmers, that might be an option for you. I have a Superchips on my Wrangler, and the most valuable function I have found on it, is the ability to adjust shifting points, so you could optimize it for the terrain in your area; hilly, flat, whatever.

I looked into a few options. I want to make sure they will be worth it economically as well in the end.

There is a generic ratio for MPG, I think it was for every 100 pounds you lose you can gain 1 mpg, so the opposite could be true. But racks and lifts, anything that creates more drag will be detrimental to your cause.

I guess you have to pay if you want to play. I just want to know how much difference it would make before committing. And weigh in the pros and cons of each upgrade.

Slowing down is one of the most efficient increases in mileage of Jeeps, on highway trips I can gain or lose 3 mpg between doing 65 mph or 75 mph, 55 is even better but just depends on how fast you want to get there. (scootr29 posted while I wrote, so he should have a better idea on the mileage drag on WK than me)

Yes, I know. I just know I am not a 55MPH driver. I guess with a little training I could be...

Thanks

 

[SSF556]

I would say 16.2 mostly city is not bad.....

EPA is 17/22


Also did you change out the orange seal at the turbo air intake to the new redesigned black seal?

 

[pixelcodex]

I would say 16.2 mostly city is not bad.....

EPA is 17/22

I read it was 20/24. I thought I could drive it for MPG when I don't feel tempted by the torque...

Also did you change out the orange seal at the turbo air intake to the new redesigned black seal?

That I did not do, and I know it has the orange ones. I read something about it on the Jeep forum, but I need to look into the part number. I also read about elephant hose mods, EGR this and that, etc. I just need to get a list and do the ones that will have a positive effect and not be mods for mods sake.

 

[SSF556]

Yes get the orange seal out...it is total crap and will lead to a clogged swirl motor which is big bucks to change out. I am running a stock engine and I believe stock is the way for me. The elephant hose mod I think is beneficial but again I just like keeping the engine stock. I do know that Custom Spooling has a DPF delete which some of the Sprinter guys are having success with. This also depends on your location....I am in SC so my engine does not get smog checked.

The EPA #s for 2007 are very optimistic. 2008 are a lot more realistic. I would stick with 17/22.

My CRD will see 22-23 cruising on the highway...that is just me, wife and doggy and a couple of bags....no car top carrier or bikes mounted to the top. Another thing is that I do not see much difference with ambient air temp...hot or cold it will run the same fuel economy.

Also do you know if Bio-diesel is being used in your area?...it will drop fuel economy as well.

 

[jluck]

Also check or delete the egr system. these are notoriously junk on these motors and go with a "green" Eco tune, delete dpf, better intake and you could see 24 mpg or better.
Diesel power did one of these recently (but I tossed the mag already) and they made big improvements.

 

[Hill Bill E.]

I have also been looking at lifts and general mods that can be done. From people's experience, how much does that affect MPG negatively? I almost wish there was a guide of sorts: I.e. Lift = -1,2 MPG, skidplates = -2 MPG, roof rack (I want a full size one to have a tent) = -2 MPG, etc. You get the idea. Even though there probably is no such guide, I am sure I can get a general guideline from people who have done the mods.

.

It is, after all, a Jeep. So anything you add to it, lift, RTT, roof rack, etc, will be detrimental to the mileage. Perhaps not as bad, being a diesel.

In my experience, ('99 XJ Limited) the difference between having a roof rack vs not, my milage dropped by 1/2-1 MPG on the highway (empty rack)

With the spare on top of the rack (33x12.5-15) my mileage dropped by 2-3 highway!

I installed a fairing, to push the wind up and over the tire, it helped some. But now on long trips, I built a tire carrier that fits in the reciever, getting the tire off the roof, during the highway driving. Gained back 1-2 MPG on the highway.

All this was extimated over many tanks of gas, during a 3K trip in a 14 day period.

With a gas engine, the MPH can have a big effect on the MPG's, the diesel's don't seem to be effected as much.

A chart would be nice, but impossible due to the different aspects of lifts, racks, etc.

But, anything that changes the areodynamics of what is already shaped like a 'brick' (Grand Cherokees not so much) will have a negative impact on the MPG's.

 

[jeep-N-montero]

I get 16.5mpg running 33in tires, so there is definitely something amiss with your CRD.

 

[Bikemobile]

Stock suspension WK 2008 4.7 v8 on all terrains. I get 20-21 mpg on long trips with the roof rack removed. Roof basket cuts 2-3 mpg's off the top. It seems like the hemis just cant seem to manage decent mpg's.

 

[pixelcodex]

There has to be an issue. I posted thin on another forum specific to Jeeps, and somebody pointed me to a thread about some ESP problems. Apparently if there are issues with some sensors, t applies light brakes at random and therefore affects MPG negatively. After reading it I touched one of the wheels when I got home, and sure enough, it seemed hotter than it should be. I have to do some "controlled" tests, with it on and off, but it sounds plausible. Have any of you guys with gasoline WKs had any issues like this or heard of anything similar.

 

[Bumzo1]

Wow that really sucks, hopefully you can figure it out. My dad has a 6.7 F-250 diesel that'll get 18.5mpg all day long