Help a damsel distressed with '99 300TD - Page 10 - PeachParts Mercedes-Benz Forum

pindoc1 · #**136** 01-26-2009, 04:46 PM

Well,,,,,my tires were a BIT low. I thought it was hugging corners a bit too good. Left front was down by 10# so there was your steering issue Terry. I put them all at 30#. Tire inflation has not been an issue in the past, however. I made routine visits to my tire guy until he went out of business this past fall. I'll recheck MPG next fill-up.

nhdoc · #**137** 01-26-2009, 05:01 PM

Quote:

Originally Posted by pindoc1

Well,,,,,my tires were a BIT low. I thought it was hugging corners a bit too good. Left front was down by 10# so there was your steering issue Terry. I put them all at 30#. Tire inflation has not been an issue in the past, however. I made routine visits to my tire guy until he went out of business this past fall. I'll recheck MPG next fill-up.

I run mine at 32 up front and 35 in the back. And those are COLD pressures which is the reference for the recommended pressures. I don't remember what the exact recommended pressures are (you can look inside your fuel door for them) but I think they are 32 rear and 30 front checked COLD.

If you put 30 in when the tires were warm (after driving) then they are still going to be low when cold because they lose a couple of PSI when they cool down.

The higher the pressure in the tires the lower the rolling resistance and better MPGs, though you will have a tradeoff in ride quality (they will be a harder ride than if the pressure is lower). I run mine higher because at the lower, recommended pressure, my tires wore unevenly.

TMAllison · #**138** 01-26-2009, 05:28 PM

The fuel door "recommended" pressure is 27 front and rear for normal driving. Seems very low to me.

PinDoc - You cant trust the gage on the air hose, ever. I usually overfill my target pressure by 5-7psi using the hose and then using my own gage lower them to what I want the next morning when they are cold.

PM me your VIN when you get a chance, there something I wanted to look at concerning options on your car thats been niggling at me. Its prob on your work orders or you can find it on the drivers door post with the front door open.

aklim · #**139** 01-26-2009, 11:21 PM

If Tim checked it out and said it seems OK and we accept that judgment, how can we reconcile with the fact that it is losing about half the mileage? What baffles me is that anyone with a car that is working in good order should be able to tell that something is wrong with a similar car that only gets half the mileage. I mean, there is going to be variation in power but not so much that it loses half the mileage and not be noticeable.

hobbitss · #**140** 01-27-2009, 12:55 AM

Quote:

Originally Posted by TMAllison

The fuel door "recommended" pressure is 27 front and rear for normal driving. Seems very low to me.

PinDoc - You cant trust the gage on the air hose, ever. I usually overfill my target pressure by 5-7psi using the hose and then using my own gage lower them to what I want the next morning when they are cold.

PM me your VIN when you get a chance, there something I wanted to look at concerning options on your car thats been niggling at me. Its prob on your work orders or you can find it on the drivers door post with the front door open.

27 is recommended for that nice soft cushy ride... It does zip for mileage, handling or tire wear... I'm running 40 to 42 in the front tires where most of the weight is and 38 to 40 in the rears with tires rated with a 44 lb max pressure... If traveling with a heavy load in the trunk I'd bump the rear pressures up to or just above the fronts... That doesn't happen often...
I also check tire wear periodically to make sure the pressures are ok for the wear across the tires... The ride is a little harsh if you like soft and cushy but the mileage is better and the handling is superior...

pindoc1 · #**141** 01-28-2009, 01:30 PM

Ok, Terry. I'll do the stop light thing. You're right though, I don't like going 100mph when there are other cars around (including the ones with red lights!). But I have some areas where I can blow through the 1st 3 gears. Thanks for checking.

aklim · #**142** 01-28-2009, 01:33 PM

I don't think it is simply tires. Unless she is running on 10 psi, I doubt that it could affect mpg that much.

Pindoc, have you got a GPS to check mileage and your speedo and odometer and trip?

pindoc1 · #**143** 01-28-2009, 04:38 PM

I am going to check it against mileage markers on the freeway this afternoon. I'll let you know what comes up.

hobbitss · #**144** 01-29-2009, 11:14 PM

Maybe time for a Scanguage 2 to monitor data in real time???
It would also help with lead foot syndrome if that is an issue...

Anthony Cerami · #**145** 02-04-2009, 07:10 PM

Pindoc1,
I have been through all the same problems with my car .....Fuel lines Glow plugs etc...,
You may consider a product called Lubro Molly ...This stuff really works I had very poor millage as well. I used this on another car and I was very impressed with the results ......Now I use one can at every fuel filter change or every 20,000 miles. I fill the filter with LM instead of diesel. It cleans the injectors.....
That brings me to the next subject ..... I found a very black substance in my fuel filter one time ...I always cut them open!... To my surprise I found that the fuel supply hose and fuel tank return hose were deteriorating.
They start at the firewall near the brake master cylinder.Then go down and around and up to the injector pump and to the large filter. They need replacing. Now is a good time to replace the fuel return lines on top of the engine ... under the black cover .....The rubber deteriorates on these lines too contaminating the system...
You will also find the flexible brake lines up front deteriorate as well . They cause the front brakes to drag ....Jack up the front and the wheels should spin freely ...if not time for new hose.
Check your tire air pressure the new tires allow more pressure try 35 PSI of air
In any event I average 36.6 MPG with my car ......

aklim · #**146** 02-04-2009, 07:33 PM

If the injectors and filters were that messed up, Tim would have noticed something like that and the smoke will be obnoxious.

I think if she really suspects injectors, she should have them removed and tested. No amount of snake oil will tell you whether the pop off pressure or spray pattern is right nor will it tell you whether you have cleaned all the crud off or not.

My injectors were fine at 100K except for 1 which had lower pop off pressure and spray pattern. One cleaning, a real cleaning and not with snake oil later and the mpg went up by at least 1 mpg.

husk · #**147** 02-04-2009, 10:54 PM

If your MPG are almost cut in half and if it was the injectors you definitely would be getting a misfire code

pindoc1 · #**148** 02-04-2009, 11:51 PM

Snake oil? I LOVE snake oil!
I checked my odometer today against a GPS and it's off by less than a tenth of a mile every 25 miles. Is that within parameters? I've blown most of the carbon out of it the past 2 wks since I saw Terry and am ready to re-fill but since I've been a little lead-footed these past 2 wks I don't think my MPG's will be up by much

Next is a trip to a very highly-rated diesel truck mechanic....

Anthony Cerami · #**149** 02-05-2009, 09:08 AM

Oh yes ....as someone mentioned before the intake needs a good cleaning...
You can also clean the Mass Air Flow Sensor....Remove using a special tool and spray it with CRC brand MAF cleaner. It removes the dust and oils.....it will improves air/fuel ratio for sure....

...I would not advise just taking out the car and beating on it just to Blow out the carbon deposits. That's where the chemical treatment (LM) comes in ...

TMAllison · #**150** 02-05-2009, 01:35 PM

Anthony - Although a proponent of Diesel Purge, IMO it will do little or nothing for the gunk down stream of the inj 's. "Blowing" cr@p out the tail pipe at WOT has helped many folks gain mpg/perfromance; especially when a car has been driven sedately whihc Pindoc acknowledged her's had been for the year that she has owned it prior to this.

Pindocs car runs great as I stated previously. No inj noise, no rough idle, no fuel leaks, no smoke, no codes, pulls hard, goes quickly, goes fast, etc, etc. It just doesnt get good MPG's at this point.

It reminds me of mine 100k miles ago. I suppose it is possible it is chipped, but don't think so personally as I ought to have been able to get some smoke out of it at WOT and it should have pulled harder IMO as well. But, I have never driven a chipped E300 so I suppose it remains a posibility.

I would also recommend staying away from the semi truck mechanic; he'll be lost and you will waste your time or cause yourself more greif.