I think it is way too late for that. My Brain is like large Hour Glass with the grains of Sand dribbling away what Intelligence and awareness I have left.

I was never ever any good at Grammar and Spelling. I only got A's in Community College English because I bought a Computer to do the Spell Checking and used only simple Sentences and punctuation.

I have never been tested but I am really sure I have always had some sort of Dyslexia. People with Dyslexia exhibit different issues and they say 10% of the Population has some form of it.
The below sums it up.
dys·lex·i·a [diss léksee ə]
n
impaired ability to understand written language: a learning disorder marked by a severe difficulty in recognizing and understanding written language, leading to spelling and writing problems. It is not caused by low intelligence or brain damage.

I only learned to read as well as I do because My Parents Paid a Tutor that I saw after School. That was a financial sacrifice for them.

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84 300D, 82 Volvo 244Gl Diesel

Sorry, Is that black or white smoke?

Im a little confused also.

Its redundant to describe how to top off a tank if you are using amount of fuel pumped and not tank capacity. For the same reason, its redundant that the fuel gauge might be inaccurate. Also, the odometer being "unreliable", various driving conditions, and "driving style" are all incidental.

My question wasn't "How do I get the mpg?" or "Why is it impossible to get a 100% accurate mpg?".

I think using the amount of fuel pumped rather than tank capacity is going to make maybe 4 gallon difference at most.

Up until now I thought 29-30 mpg was normal for w123.

I guess my question is: Im getting low mpg. What can I do to the car mechanically to improve this?

-What should I look for to check if the breaks are rubbing? Is it visually simple to check or do the wheels need to come off?

-The one thing I've left unchecked on this car is fuel injector nozzle spray quality. All things 123 considered, Is this a common major cause of unburned fuel, causing my white smoke, and substituent influence on miles per gallon?
Originally i thought it was my ALDA adjustment but if im learning here: bad timing could be wasting my fuel, correct?

Thanks

Unburnt Fuel produces white Smoke that smells like Diesel Fuel. Black smoke is Fuel that did not burn well.
Gray smoke also falls into the catagory of Fuel not burning well but the Fuel is burning better than if it was putting out Black Smoke.

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84 300D, 82 Volvo 244Gl Diesel

Kalikar,

Does your total mileage odometer work correctly? It would be nice to read the tenth mile of the trip odo, but not necessary for our purposes. About the only way to get an accurate MPG reading is:

o. Fill it up and write down the odometer reading
o. Drive it under the same conditions it is normally driven.
o. Fill it up to the same level as before and write down odometer reading & gallons pumped.
o. Subtract the first odometer reading from the second, that is your miles driven.
o. Divide the miles driven by the gallons pumped.

Most any other method, such as using the fuel gauge to determine fraction of a tank or some such is NOT accurate enough to be any indication. Run a tank or two, calculating like this and then we have a much better baseline to discuss. The other methods are guesswork.

For a turbo 300D to get 29 to 30 MPG, in my experience would only happen on a long, steady speed highway trip with cruise control if ever. Maybe others have had different experience than this and I hope they will chime in.

Again, what kind of driving are you doing? City? Highway? Lots of stoplight to stoplight with a heavy foot?

If you are doing city driving with a heavy foot, 19mpg would not be surprising. If you are doing highway driving with few or no stops, then 19mpg would indicate a problem.

Hope this helps.

__________________
2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

Annoy a Liberal, Read the Constitution

As stated, black smoke is partially burned fuel. Unburned fuel comes out white and smells strongly of fuel. If you're burning coolant, that will also come out white, but with a much different smell. In cold weather you can also get water vapor out of the exhaust. It looks like white smoke, but doesn't have the smell.

That's okay. We want to help.

Actually, those are all relevant. If you don't top the tank off the same way each time, you will have additional error in the accuracy of each mileage calculation. If you average many tanks, this will take care of some of the error, but it's better to have a more accurate picture of the mileage you're getting at each fill up if you're trying to troubleshoot a fuel economy issue. Also, if the odometer is inaccurate or inconsistent, you will not have good data from which to work. On cars this old, any odometer is suspect until you have tested it.

It's true you didn't ask those questions, but you must implement the answers in order to know whether you have a fuel economy issue at all, and what its severity might be.

Four gallons is a lot. For example, lets take your 406 miles before filling up and say that it only took 17 gallons to fill up. 406/17=23.9, which is pretty normal for a 300D. On the other hand, let's say it took 21 gallons to fill. 406/21=19.3, which is low but possibly normal depending on driving style and conditions.

That's possible under the right conditions and a light foot. However most of us get considerably less.

Properly calculate your mileage to find out if you're really getting low mpg and come back with data along with some more information about conditions such as city or highway driving, typical cruising speeds, and general heaviness of your foot, and we can tell you whether what you're getting is normal or not.

The easiest is with an IR thermometer. Drive for a while without braking and then come to a stop doing as much coasting and as little braking as possible. Then shoot the rotors with the IR gun. If a brake is sticking, that rotor will be considerably hotter than the others. Be warned that sticky brakes may not stick all the time, so multiple test runs are desirable.

Short answer: sometimes and maybe. Run a good check on your mpg as described and we can move from there.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

Kalikar,

Firstly, undo whatever you did to the ALDA. Adjusting the ALDA is not a fix for poor performance. Adjust it to where you get just a little puff of smoke when you rev the engine in park.

Secondly, your numbers are not as abnormal as you think. In my SD, I get 20-22MPG very consistently. Last time I checked my odometer, it was acceptably accurate against a GPS. I spend a good amount of time at stop lights, have a heavy foot and when on the highway, I usually cruise between 65 and 80MPH. I also have the A/C on constantly.

Other members have already mentioned how you should calculate your MPG and how different things can affect your MPG. Injectors are one thing that can have an effect on MPG and you should at least test the ones you have. In all reality, your MPG numbers are not out of the ballpark but could be better; especially since you are driving a CD with less curb weight.

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

Everybody get this, install it and just be done with the MPG debate.

https://www.atlas-scientific.com/product_pages/sensors/small-flow-meter.html

__________________
Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

You would need two of them so you could subtract the return fuel from the supply fuel.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

Ok this is too much confusion for a simple process, just fill up the car and not only till the pump clicks off the first time. Wait a few seconds after it clicks and top it off. OK Now get in and push the trip odo button. Drive.....pull into fueling station, repeat the above procedure top off the tank. Take the number of gallons you were able to pump and divide by the miles on your trip meter walla! Miles/gallons or MPG.

Thats what the OP has been told at least half a dozen times by various people in this thread. He refuses to do it. Instead he obfuscates the issue by simply looking up the fuel capacity of his car (21.133 gal) and claiming that how much fuel he used to travel 406 miles.

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CENSORED due to not family friendly words

Brilliant, just brilliant! Why didn't I think of that?

Let's consider your idea as if it were a serious proposal and go through the logic

First, diesel engines use only part of the fuel that goes to the injector pump. The rest is returned to the tank. So we need a method to get at only the fuel actually used. So we have essentially two choices - we can either install two flow meters, one for the supply and one for the return and take the difference as a way to get fuel used. Or, we can use some sort of a float system whereby the return fuel goes into this rather than being returned to the tank. This way the lift pump draws only from the float bowl. Ah, but since we need a way to replenish the float bowl with make up fuel, we need to add an additional fuel pump to pump fuel from the tank to the float bowl. Now there is a problem with this, aside from introducing several additional points of failure, and that is that the purpose of excess fuel is to provide cooling to the IP and injectors. Unless you add heat dissipation capability to your float bowl you defeat this purpose and potentially damage the engine.

Second, the device you suggest is only a flow sensor. It provides one pulse per unit of fuel that must be read and processed by a microcontroller to actually get flow rates. Microcontrollers are no big deal - Arduino controllers are a few bucks and have been used in these applications, however programming them is likely beyond the scope of most members of this forum.

Third, in order to get miles per gallon, you need to not only capture fuel usage per unit of time, you need to capture distance per unit of time. To get this you need a sensor somewhere to read a pulse per unit of distance. While it's possible to grab the VR signal from the speed sensor (if you happen to have one on your transmission) it would be better to use a dedicated Hall sensor on the driveshaft and use that. The calculation is quite simple once you have the fuel flow pulses and the distance pulses, but again, programming is needed to get the number to output.

Fourth, in order to have something useful, you need an output display. For my engine instrumentation project (Engine Instrumentation Project) I used bluetooth to connect to an old Android phone which provided the display using a Processing program running in Java.

Fifth, your choice of a flow sensor is pretty lame. The lower limit for the sensor you proposed is .8 liters per minute, or 48 liters per hour or, as I'm sure you know, a little over 12 gallons per hour. Let's just take a quick example of a car going 60 mph using fuel at 12 gallons per hour (the lower limit of the sensor), that would mean that 4.7 miles per gallon is the lowest reading we could expect to measure. Might be fine for a tractor trailer or an earthmoving machine, but inappropriate for a MB diesel.

Now if you want to figure out whether your mileage is in the ball park, this is the best way I've seen to do so.



While this graph is specifically for the 300 SD running in 4th gear, the engine should be the same for most of the turbo 617s we drive. So the difference would be the road load line which would be slightly different based on weight, rolling friction and coefficient of friction. The chart is given based on engine speed, but this can be converted to mph by simply knowing the rear end ratio.

Hope this helps a bit.

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

Hey man. You wanted to lay out the logic behind it. I just gave you a reason. I just happened to be shopping for accurate flow meters at the time for a completely unrelated project.

FLow is not what you need to know. Its total volume used/whatever.
Best way i say to figure MPGs in a MBZ would be to install an axillary tank with precise volume graduations. Take out all the guess work in trying to figure useage.

Go out and get some Oz fuel used/beer run stats

__________________
Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

If your '85 has CA emissions, you may have a clogged trap-ox......Rich

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All Diesel Fleet
1985 R107 300SLD TURBODIESEL
2005 E320 CDI (daily)

LOTS of parts for sale!


EGR block kit
http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html

1985 CA emissions 617 owners- You Need This!
Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst.

Sanden Instalation Guide (post 11):
http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html