If I used the same pump, what inaccuracies would there be? Normally I fill until the vent hole, meaning the whole neck is filled. Only once did I spill which was due to low light and being tired. Good thing in a way as saw the diesel was green.

I don't need to obtain 30M.P.G., but be elated with consistently getting 27M.P.G.. However, I am not going to make permanent modifications.

I was told where maximum torque was is where one should drive. Being at 2.500 R.P.M. means 110K.P.H. When I drove from Sandy Eggo to here I drove VERY careful and slow. My mileage was way worse (24M.P.G. I.I.R.C.) and took me another two hours! I rather go 75 to 80M.P.H., be safe, and get to my destination in less then seven hours, preferably five to six. So be it if I get 24M.P.G. as time is money!

Just because you are lucky like Vater driving his 1964 Beetle at 45M.P.H. on the freeway doesn't mean it isn't true. It was from a Caltrans worker from experience and others. I bet if you Googled it you find the data we seek.

Well tried to do a video, but not working out. I am used to the metric system, so spoke wrong. 70M.P.H. is 2.500 and 75M.P.H. is about 2.700R.P.M.. My data is accurate as I used a G.P.S. and am sure the tachometer is correct. If you want you can come check it: I have too much to do to bother. Need at least a days notice.

Tram, good point that I forgot! Merging does require some speed and tack. There is an on ramp for Ardith Rd./S.R. 52 that if one doesn't go at least 60M.P.H. they will be dead; it has happened a few times. It is a sharp curve with a short strait so requires a good bit of acceleration. Most who never used it fail miserably because they are so scared. I would avoid it in an air cooled Volkswagen just to be safe.

Skippy, I like that! :D

OK.

Last week I filled the fuel tank up until I could see clear fuel at the filler neck. I waited for the foam to settle, etc. I always use this method when tracking MPG. Reset the trip odometer. I drove my normal routes to work, etc. Mixed city and highway. I drive 65MPH with the cruise set on the highway unless I have to pass someone. I drove the car until the gauge read just under the R. I pulled into the same station and used the same pump as the first time. I filled the tank in the exact same way.

The car took 15.138 gallons and traveled 274.2 miles. That gets me 18.11 MPG.

I don't drive too aggressively but I don't fall back too much in traffic, either. People usually pass me off a stop light.

I did not use any fuel additives, etc.

I state that the fuel economy that you recorded is impossible. 18.11 would require severely retarded IP timing and or some dragging brakes. If this were the situation, the 0-60 time would be 18 seconds or more despite proper boost from the turbo.

My bet is that you have a slipping odometer. The SD was down to 23 mpg until I finally made a check and realized the problem.

That is actually a very good call. I agree that there is no way possible that this car can run anywhere close to 'normal' given that MPG, and a "slipping" odometer is not uncommon.

I might have all of those problems you listed. I am going to check my timing chain stretch next time I have the valve cover off. I think my timing is retarded because I do get white smoke at idle and it smells fuel-rich. Brake overhaul is on the list of things to do. 0-60 is not the best but she has her days. I'll check here and see if I can find some threads on the slipping odometer issue.

I did some calculations against my odometer today on my lunch break. Here are the numbers I got.

Depart:
Trip: 198.85
ODO: 386683
GPS: 11127.2

Return:
Trip: 221.95
ODO: 386706
GPS: 11152.9

Miles driven:
Trip: 23.1
ODO: 23
GPS: 25.7

That comes out to an 8.9 percent difference. I estimate I would be getting 19.72 MPG in reality given these test numbers. Not a huge difference.

Thanks for obtaining solid data. I have been proven wrong and so state it here.

The vehicle clearly has severe issues with regard to IP timing or cam timing or compression. Such fuel economy is nothing short of abysmal.

I strongly urge you to obtain the required equipment and tools to verify both cam timing and IP timing at the earliest opportunity. If these do not provide some enlightening information (which I am fairly sure they will), then a compression test is in order.

Additionally, it might be time to pull the injectors and have the nozzles replaced and balanced. The white smoke doesn't bode well for complete combustion.

FWIW, the SD went 540 miles and I filled it with 18.1 gallons yesterday. This is combined city/highway with winter fuel. Nothing short of amazing.

Brian,

You are getting some great MPG! I hope to attain those numbers some day.

IP timing is in the plans. I still need to do research on it, etc. I am thinking I might as well replace the timing chain and guides since I know the car has well over 250K on it and I have no records saying it was replaced. I think checking for stretch may give me a good idea if it needs to be changed or not. I'll be checking that next time I open the valve cover; which should be soon as it has almost been a year since my last valve adjustment.

I rebuilt, tested and matched my injectors last summer with new Monark nozzles. All spot on at 1950 PSI and great spray patterns. I plan to take the injectors out, re-test them after they have settled in and see what I've got. The white smoke is not consistent and could (remote possibility) be related to a clogged fuel tank vent. I get suction when I open the cap. Can't seen to get the clog out of that dang tube. I notice the white smoke more in the cold. GPs do need to be replaced with Bosch but I did pull out 3 bad ones and replace them with (cough) Autolites that I had hanging around. All plugs seem to be within range of spec, but I have 5 Bosch plugs waiting to go in when I get the time.

I did acquire a compression tester a few months back from HF tools. I am hoping it is good enough to do the job. The test WILL be done when I pull the injectors for testing.

Hi Eaton
The EPA combined mileage for an 85 300D is 21 mpg at fueleconomy.gov.

Besides the tuning issues, so much depends on how soon you can get it into top gear and how hard you press the foot feed down. I run my shifting cable loose. It can go into high gear in town at light throttle. I have had 6 fills in my car with an average of 27.5. I could imagine getting 21 mpg with stronger acceleration and running at over 60 mph all the time.

I'm not really counting MPG right now. I need to get my transmission adjusted and shifting properly. Sometimes it shifts too soon. It is missing the vac orifice and the kickdown cable needs to be replaced. It's all on my list...

So Brian said if I kept it under 65M.P.H. I would get good economy. Nope, got 19M.P.G.

Left the valley Sunday afternoon and came back Monday night. I really romped it even hitting 90M.P.H. where safe to be able to get up the hills, but most times 80 to 85M.P.H.. Know what? I got between 21 and 22 M.P.G.. Last time when I was careful I got 24M.P.G. but took me seven hours. This time was five, and well worth the difference in cost. I rather get better mileage and be safe.

Your data is flawed and it puts every statement you make into question.

It is physically impossible to get 22 mpg doing 85 mph and get 19 mpg doing 65 mph.

You might as well be a storyteller. Have no fear, there are plenty of them on here.

Brian, too bad you were raised so poorly. I too didn't have a Mother, but even I can figure out this is not polite. Hurts to be wrong, doesn't it? Go get your nickers in a wad somewhere else if you have nothing helpful.

As for others, I have checked my speedometer with my G.P.S. and spot on except over about 80 M.P.H.. Then it is about a mile slow, I.I.R.C..

Actually, it was mostly below 60M.P.H. for the record, mostly around town.

Also, when I fill up I fill the whole neck. So there is no discrepancy in the amount except if the pump meter is off. However, that would not explain the difference.

I will say does feel more responsive, idle is smoother, and the knock at shut down is less since all the romping. So diesels do like higher revolutions WITH load. I now do an Italian on the way home. I am quite impressed with the extreme acceleration when I drop it in third. Came in handy to get out of a tight spot: 65M.P.H. to 85M.P.H. in a hurry. Weeee!

Anyway, need to get back to work...