Help a damsel distressed with '99 300TD - Page 11 - PeachParts Mercedes-Benz Forum

aklim · #1 02-17-2009, 11:57 PM

Quote:

Originally Posted by pindoc1

Terry has looked at my car and I think he said it hasn't been modified. He said it runs better than his so I don't know what the problem is.

Only mods that I can see would be a chip and few people do that so I think he is probably right.

I know that on my Speed Density cars, they ignore some sensor inputs when under WOT acceleration and go off certain tables. That is why I am wondering if there might be an issue with the MAF when you are NOT doing WOT. Reason I suggested that was because it doesn't cost us much to try.

pindoc1 · #2 02-17-2009, 11:53 PM

I grew up off Buckeye Rd. My folks still live there and used to be all farm houses when we moved in. I was back in October for my Dad's 80th.

aklim · #3 02-17-2009, 11:58 PM

Quote:

Originally Posted by pindoc1

I grew up off Buckeye Rd. My folks still live there and used to be all farm houses when we moved in. I was back in October for my Dad's 80th.

I know that place too.

And you didn't stop by and say "Hi"? Jerk.

nhdoc · #4 02-18-2009, 07:15 AM

Getting back to the question at hand...how can a car which otherwise runs normally be only getting about half the mileage it should be getting? We confirmed it was running normally by having Terry drive and examine it. He owns the same model and confirmed there is nothing unusual about this one. Typically, things that come to mind which would affect MPGs could be:

1) dragging brakes (let's assume you don't drive with one foot on the brake pedal - so called "riding the brakes")
2) slipping tranny
3) clogged exhaust
4) bad injector(s)
5) injector timing
6) fuel leaks
7) ECU/Sensor problem

Since Terry says the car drove more or less "normally" I would tend to eliminate 1, 2, 3 and 4. That leaves 5, 6 and 7. I'm assuming Terry also would have noticed fuel leaks, even if they were not from the usual locations, though you could have one that only occurs under certain conditions. I guess if it was my car I would have the injector pump timing checked to make to someone didn't mess with it. It is not that costly to have it done, even at the dealership...I would guess a couple hours labor if they claimed they had to remove the Intake Manifold to do it.

I'd also invest in a scangauge II and try and monitor MPGs from it to see what it reads. That will confirm if you really are completely free of any leaks. Maybe you have a leak which only occurs while you are driving?

hobbitss · #5 02-18-2009, 11:36 AM

Agreed...
Scangauge II would be a great diagnostic tool AND it will help you keep your foot out of the Injector Pump....

aklim · #6 02-18-2009, 11:45 AM

Quote:

Originally Posted by nhdoc

bad injector(s)

injector timing

fuel leaks

ECU/Sensor problem

I would guess a couple hours labor if they claimed they had to remove the Intake Manifold to do it.

I'd also invest in a scangauge II and try and monitor MPGs from it to see what it reads. That will confirm if you really are completely free of any leaks. Maybe you have a leak which only occurs while you are driving?

When I had 1 injector with poor spray pattern and low pop off pressure, it felt pretty normal but I picked up 1-2 mpg after cleaning. IF she had 6 such injectors, I am pretty certain Terry would have found something sluggish when he drove the car.

Injector timing. I suppose. I don't think so either because my chain stretched and I had it set back a few degrees but not much changed either, MPG wise. So, for it to do that with the chain that affects injector timing, I would think the chain has to be pretty far stretched. Still, an MB shop has the right tool for checking the timing.

I doubt it is fuel leaks. For that to be true, her belly would be wet. You wouldn't have to even take it off to see it. The fuel would be all over the floor.

That I am thinking which is why I offered to lend her my sensor to check.

Do you have to take the IM off to check it? Probably so to adjust it but I am not sure if checking it needs the IM off. I will have to check. I thought it was that she would need something hooked up to the battery and a part of the car but that was a long, long time ago in a galaxy far, far away.

TMAllison · #7 02-18-2009, 12:38 PM

Quote:

Originally Posted by nhdoc

1) dragging brakes (let's assume you don't drive with one foot on the brake pedal - so called "riding the brakes")
2) slipping tranny
3) clogged exhaust
4) bad injector(s)
5) injector timing
6) fuel leaks
7) ECU/Sensor problem

Since Terry says the car drove more or less "normally" I would tend to eliminate 1, 2, 3 and 4. That leaves 5, 6 and 7.

I believe I actually said it accelerated much stronger than mine; reminded me of mine 100k miles ago.......It pulls strongly, but not to the extent I felt it was chipped. Our timing chains aren't under as much tension as prior engine designs so i doubt that is the problem and if it were it wouldn't pull as well as it does. Same goes for the ECU/Sensors/Control. Same for the MAF; drives too well and there arent any codes. Can also say there were no fuel leaks when I looked at it (tiny bit of old staining at the pre-filter) and no evidence of fuel blowing back, on the belly pan below or to the rear of the undercarriage.

All the fuel lines were routed correctly too which was my personal smoking gun that I expected to find.

Doesnt the scangauge need to be calibrated to "your" vehicle to report mpg's? Thats done via the mileage reported on the dash odometer? Is that really going to tell us anything more than doing the division long hand will?

Connie - The air we breath is 78%(?) nitrogen. To me the this is just another profit center for the tire stores.

If you are down in the Bay Area again I'd be happy to look it over a second time and see if anything has changed.

JimSmith · #8 02-18-2009, 01:28 PM

The ScanGauge II device I have will read instantaneous and average mileage without being "calibrated" beyond knowing it is a six cylinder Diesel. If you want to have the unit give you running tank and trip averages you have to tell it how much fuel you put in the tank when you fill it up. This feature gets confused if you skip a tank. And my odometer and the ScanGauge II odometer don't agree. Not off by much, but several miles per tank.

Jim

hobbitss · #9 02-18-2009, 03:29 PM

Quote:

Originally Posted by TMAllison

I believe I actually said it accelerated much stronger than mine; reminded me of mine 100k miles ago.......It pulls strongly, but not to the extent I felt it was chipped. Our timing chains aren't under as much tension as prior engine designs so i doubt that is the problem and if it were it wouldn't pull as well as it does. Same goes for the ECU/Sensors/Control. Same for the MAF; drives too well and there arent any codes. Can also say there were no fuel leaks when I looked at it (tiny bit of old staining at the pre-filter) and no evidence of fuel blowing back, on the belly pan below or to the rear of the undercarriage.

All the fuel lines were routed correctly too which was my personal smoking gun that I expected to find.

Doesnt the scangauge need to be calibrated to "your" vehicle to report mpg's? Thats done via the mileage reported on the dash odometer? Is that really going to tell us anything more than doing the division long hand will?

Connie - The air we breath is 78%(?) nitrogen. To me the this is just another profit center for the tire stores.

If you are down in the Bay Area again I'd be happy to look it over a second time and see if anything has changed.

Hey Terry...
Have you cleaned out your Intake Manifold?? I cleaned mine last spring at about 112K and it made a very noticeable difference in performance.... Temporary cure for the Curses of EGR soot and the resulting loss in performance...

Pure Nitrogen is used in some performance environments to eliminate the effects of Oxygen in aging the rubber of a tire... Additionally there was a discussion in a Public Safety forum about the use of pure nitrogen in RIBs (Rubber Inflatable Boats) stating that the nitrogen reacts less to temperature fluctuations minimizing changes in chamber pressures do to environmental changes... The question is: Is it worth the investment in time and money for you???

pindoc1 · #10 02-18-2009, 11:42 AM

I don't ride the brakes and I think Terry would've noticed any of these first items. If I still have a fuel leak I would be really p.o.ed with all the $ I jsut spent fixing the ones I did have.
OK, I can get a scanguage. Where do you get them? Any special kind? I can also get the injector timing checked. That sounds like a good plan.

aklim · #11 02-18-2009, 11:46 AM

Quote:

Originally Posted by pindoc1

OK, I can get a scanguage. Where do you get them? Any special kind?

I can also get the injector timing checked. That sounds like a good plan.

http://www.scangauge.com/

MB has a special tool to do that. I heard they can do the drip method but I prefer the accuracy of a digital readout as opposed to a tech using fuel drops to tell.

KarTek · #12 02-18-2009, 01:59 PM

I was messing with my SCII this morning and it shows me getting horrible mileage. I don't know what's not set but something's wrong. I set the tank size, engine size, fuel type. What else is there?

JimSmith · #13 02-18-2009, 02:54 PM

There are two Diesel settings. You have to pick one and run a test where you give it some throttle and see which way the numbers go. If the are correct per the manual you leave it, if not you pick the other Diesel mode. I think I had to change mine from the default setting. Not a big deal, and it is outlined in the manual, which is available from them on-line.

Jim

KarTek · #14 02-18-2009, 04:05 PM

Which one is P0243?

TMAllison · #15 02-18-2009, 04:13 PM

wastegate circuit A(?) malfunction; MB code P1_470. Vacuum transducer beneath air filter activates wastegate. When code trips = no turbo until reset.