fuel mileage question

bigmaho · **Posted:** Thu Oct 02, 2008 11:04 pm

My 06 speedometer is about 5% fast but my Wranglers are not stock.

warp2diesel · **Posted:** Thu Oct 02, 2008 11:12 pm

bigmaho wrote:

My 06 speedometer is about 5% fast but my Wranglers are not stock.

My Speedo is also 5% fast but the odometer is 10% slow and has to be corrected to get accurate mileage readings.

KJ79 · **Posted:** Fri Oct 03, 2008 12:07 am

Thanks for the responses.
I don't think my CRD has an air in fuel problem.....at least the plunger is usually firm and when I bleed with the bleeder I get only a tiny amount of air - the filterhead was changed once by the dealer.
My speed and odometer checked out 99% accurate with my GPS....
Mileage difference is I get 40% less miles (almost half !) the miles per tank as a lot of other CRD's are getting. A odometer being out by a couple of points is not gonna help that measurably.
Yes, F-thirty-7 was invoked.
EGR and AFV replaced this summer - I suspect I would not have a big built-up of CRuD in the AFC.
Turbo kicks in with a vengeance after the usually initial lag. Seems OK.
Why the bad odor ? It is sort of like a real burnt sooty smell, not like a 'pleasant' diesel smell (like I had on my TDI), it is a kind of vile smell, whether hot or cold it is there. Have to keep the windows tightly closed when the engine is running or I'll die. Never had this the first 2 years. I mentioned the grayish/brownish smoke going up the hill, this is with a warm engine at about 105 F ambient.
Any more useful suggestions out there?

onthehunt · **Posted:** Fri Oct 03, 2008 4:24 am

Maybe you have a return line leaking on the top of the engine? On a seperate note I have a hard time believing anyone is saving fuel by using an E-rated tire no matter what the psi your running. What's the weight difference between the stock and E-rated tires? I've ran E-rated tires and just about everything was affected negatively.

tulsa · **Posted:** Fri Oct 03, 2008 6:41 am

onthehunt wrote:

Maybe you have a return line leaking on the top of the engine? On a seperate note I have a hard time believing anyone is saving fuel by using an E-rated tire no matter what the psi your running. What's the weight difference between the stock and E-rated tires? I've ran E-rated tires and just about everything was affected negatively.

I agree, look at the weights of those puppys.
Lewis

fastRob · **Posted:** Fri Oct 03, 2008 11:20 am

KJ79 wrote:

Thanks for the responses.
I don't think my CRD has an air in fuel problem.....at least the plunger is usually firm and when I bleed with the bleeder I get only a tiny amount of air - the filterhead was changed once by the dealer.
My speed and odometer checked out 99% accurate with my GPS....
Mileage difference is I get 40% less miles (almost half !) the miles per tank as a lot of other CRD's are getting. A odometer being out by a couple of points is not gonna help that measurably.
Yes, F-thirty-7 was invoked.
EGR and AFV replaced this summer - I suspect I would not have a big built-up of CRuD in the AFC.
Turbo kicks in with a vengeance after the usually initial lag. Seems OK.
Why the bad odor ? It is sort of like a real burnt sooty smell, not like a 'pleasant' diesel smell (like I had on my TDI), it is a kind of vile smell, whether hot or cold it is there. Have to keep the windows tightly closed when the engine is running or I'll die. Never had this the first 2 years. I mentioned the grayish/brownish smoke going up the hill, this is with a warm engine at about 105 F ambient.
Any more useful suggestions out there?

Have you done the ORM and EHM? Why not? They are very easy and cheap.
Otherwise maybe you will have to clean out some hoses maybe the intercooler.
Just checked the MAP in mine and it was clean after 10,000 miles. When I first checked it before the ORM and EHM it was nasty and gave me the greatest mileage improvement of all mods so far.
My speedo reads 70 at 65 by GPS, the odometer seems close enough to GPS though I have not really checked it closely.
Just sounds to me like your motor is choking on some crud buildup.

ATXKJ · **Posted:** Fri Oct 03, 2008 11:36 am

KJ79
The smoke and smell sound like you're have a lot of excess fuel - which seems to say either the nozzles are off - or timing -
There's a lot I don't know about diesels - but somewhere there should be a sensor that identifies the crankshaft position - for the computer to calculate the injection pulse - I'd expect it to have a CEL (or if dead the engine would be dead) -
but maybe it's just out of position or dirty - and giving inaccurate readings. ??

Are the power levels okay? (turbo hoses cause a lot of smoke - but huge power loss)

fastRob · **Posted:** Fri Oct 03, 2008 7:58 pm

Wondered if your Catalytic converter was clogged?

KJ79 · **Posted:** Sat Oct 04, 2008 3:18 pm

Thanks, I'll try to respond here to the many suggestions.
a.) Why I did not do the ORM? - I did but it made 0 difference in mileage - it did make the engine note more clattery though.
b.) The engine does not seem to gunk up that badly, judging by the amound of crud on the MAP sensor. I check the MAP usually when I change the oil and clean the little bit of dirt off - does not seem to make any difference though. Just in case it was a bad sensor, my dealer changed it out for a new one, again no difference.
As I did not seem to have a lot of built-up I did not do the EHM. I am not sure, has anybody experienced better mileage after the EHM?
c). Fast Rob suggested the cat may be clogged up, I have not checked but would expect the performance to be really poor - I mean in terms of accellaration it seems all normal. Even when pulling my trailer. Note my mileage did not drop a lot while pulling the 3000 lbs trailer, in fact it hardly made a difference (I guess it cannot drop worse than it is 14 mpg).
d). The suggestion of the crankshaft sensor being out of position, possible.; Is this adjustable. The timing of the fuel pulse is critical. The engine does sound a bit different. Don't know how to describe it but it used to sound a lot like the purring of the VW TDI I used to have, the engine is making a more "stamping" sound (at idle).

nursecosmo · **Posted:** Sun Oct 05, 2008 10:30 pm

KJ79; it sounds like a problem with an injector or injectors. If the Crankshaft position sensor was misaligned, there would be significant drop in performance. The brown/grey smoke indicates that fuel is being injected late in the stroke(due to a sticky injector) or even continuously. A malfunctioning rail pressure sensor can also overfuel but will produce black smoke not grey/brown. One other possibility is a broken or cracked nozzel. It is expensive but you might want to have the injectors checked as they don't always throw a code when they malfunction.

Anomious · **Posted:** Mon Oct 06, 2008 3:31 pm

Your EGR flow control valve is not opening all the way.

L.

It happened to me, same symptoms.

onthehunt · **Posted:** Mon Oct 06, 2008 4:05 pm

I also would check your pcv valve for proper operation. It could be venting under the hood.

KJ79 · **Posted:** Mon Oct 06, 2008 5:26 pm

Alright, as soon as I cen get it to the dealer I will list all the possibilities suggested here (I am still under the 70,000 miles 7 year warranty. I will be taking it to a dealer of who I know he services Cummins, Sprinters and CRD's. I know of 2 other crd's that have been serviced there and are getting around 30 mpg and I spoke to one of their diesel mechanics. He seemed to know what he was talking about.
I will post the outcome hopefully in about 2 weeks time.

Hjalti · **Posted:** Mon Oct 06, 2008 6:57 pm

Hi K79

Thank you for sharing this. I have been watching this thread and am very interested in what you will find out since I am also not altogether satisfied with my mileage. Perhaps I am experiencing something similar. Good luck.

vegiH · **Posted:** Thu Oct 09, 2008 12:08 am

I too have a hydralic typt burning smell,I suspect cat,here kitty,kitty.I will do SEGR,and then want ever you find to remedy this .We only own diesels,with this our newest(2000 excursion 7.3 Vegistroke,Libby 2005 custom WVO system,porsche 924-kubota project),goodluck,keep posting,,,,,,,,,

KJ79 · **Posted:** Tue Nov 04, 2008 1:52 am

While the forum was down I took it in and the technician found the following:
(from the work order): checked for poor fuel economy & lack of power, very sluggish and can smell exhaust in vehicle.
Checked exhaust flow-low.Checked for leaks, leak at exhaust manifold,Re&Re drivers intake & turbo-outlet. Found and repaired EGR tube clamp not tight.Replaced

Sofar, I can say only that the smell seems to be less and that driveability has improved. I have not seen smoke either but the weather has turned to dark and gloomy, so it is hard to see it now.
I just filled it up to check actual mileage. By the end of the week I will likely fill it up again and will report the figures - with all fingers crossed hoping to get north of 14 mpg :oops:

CounterCulture · **Posted:** Tue Nov 04, 2008 10:26 am

Still being new to CRD ownership, I had a few issues myself. Heres the rundown. I drive aprox 15 miles to work one way, 10 being freeway, speeds aprox. 65-70mph and 5 miles stop and go city. My best average mph was only 22mpg and thats with the orm. Since ownership i've only run shell gas, and usually anything from 5-20% bio. I haven't removed the map sensor to clean it yet, and my tires are aired down a bit, maybe 35-40psi tops. I have a 2006 with 22k mi, a 2" lift and 31" Coooper sst tires, is this less than average for these kinds of mods? My normal mpg with more city driving is around 18-19 and I drive it easy. I'd love to do more mods for mpg, but I have a 7yr 70kmi bumper to bumper warranty and don't want to void it. I'm going to clean my map sensor and put a bit more air in the tires and see how that goes.

nursecosmo · **Posted:** Tue Nov 04, 2008 10:38 am

CounterCulture wrote:

Since ownership i've only run shell gas

Well there's your problem right there, you are putting the wrong kind of fuel in it. :roll:

But seriously, those are some heavy tires. The 2" lift doesn't help either. Do the ORM and air up your tires and you should pick up at least 2-3 MPG.

Joe Romas · **Posted:** Tue Nov 04, 2008 10:56 am

CounterCulture.
You and I are in the same boat :lol:

Mine has 20k miles and I've also got the 7/70 extended warranty. My highest tank ever was a dissappoiting 25 for all highway at 65-70 mph. My last fill up of intown only with short trips was 23.4. It's getting better. But at 20k both of our jeeps are not broken in yet and will not get their best till they are :roll:

My past VW's started improving at 20k but I don't think the CRD's break in point has been determined yet. I consider my intown mileage good but am so far dissapointed in highway figures :cry:

Your tires may also be hurting you. I still have the original bad years :lol:

All last winter I was averaging 17 to 19 mpg for my short trip city driving. I got the same numbers (17-19) pulling our #3500 camping trailer to the outer banks of North Carolina this summer that took us 1800 miles over the mountains of Virginia and West Virginia and I consider this good also :wink:

At any rate it's intown is double that of my 99 Cherokee with the I6 4.0L and highway is about the same.

CounterCulture · **Posted:** Tue Nov 04, 2008 11:00 am

I wish I could get 25! I'd be happy with that! I've been lazy about cleaning my map sensor, i'm sure doing so and adding some air to my tires will improve my mpg. It would be good if I drove a little further distances too. Forgot one thing. When is it necessary to prime the fuel pump? I've never actually done it, is this bad?

fuel mileage question

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