Altitude Compensator - PeachParts Mercedes-Benz Forum

oldsouth · #1 03-23-2002, 11:53 PM

Does anyone know where the altitude compensator is on a 1995 S-350 Diesel and how it functions.

pilot2000 · #2 03-26-2002, 01:04 AM

A What????? "altitude compensator "

Sorry never heard of one and, I sure would love to knwo what the heck is it.

oldsouth · #3 03-26-2002, 10:24 AM

I found out it is in the computer. Don't know exactly how it works or what it does. Probably fuel air mixture. Don't get me wrong, I love Mercedes cars but they will tell you NOTHING about them. All Mercedes says is ask the dealer or take it to the dealer. When you take it to a dealer you are talking to some service advisor that does not work on them and cannot answer your questions. No books or manuals telling about the 140 cars. This is totally pathetic. There are some of us out here that likes to work on our own cars and have the mechanical ability to do so if we only had some type of manual or guide. Mercedes SUCKS in this area!

P.E.Haiges · #4 03-26-2002, 11:24 AM

Tha altitude compensator (AC) reduces the fuel to air ratio at higher altitudes where the air is thin. My '74 240D didn't have one and it poured out black smoke at high altitudes but never smoked at sea level. My 300SDs have the AC and do not smoke at high altitudes, but they also have the turbo charger which puts more air into the cylinders. and tends to keep the air/fuel ratio constant.

The AC is mounted on the end injection pump and adjusts the rack according to atmospheric pressure. I imagine on any of the computer controlled injection systems, gas or Diesel, the AC would be an electrical input into the computer.

P E H

oldsouth · #5 03-26-2002, 11:38 AM

PEH - Do you know on the 1995 S-350 if the altitude compensator is on the pump and does it work with the pump only or is it controlled by the computer. On my car, I have disconnected the EGR and changed out the wastegate on the turbo to a pressure operated one instead of a vacuum operated one. The wastegate is no longer controlled by the computer. I did not know if this had an effect on the altitude compensator not working or not. Just got back from a Colorado trip and the car billowed smoke out at idle and low speeds. First time the car has been at a high altitude. Seemed to be overfueling.

oldsouth · #6 03-26-2002, 11:41 AM

Also - do you know if 15 lbs of boost at sea level is the same as 15 lbs of boost at 10,000 ft? Is there the same amount of oxygen there?

P.E.Haiges · #7 03-26-2002, 12:04 PM

Oldsouth,

Sorry I don't know anything about any computer controlled engines gas or Diesel. I'm from the old school.

If you are billowing smoke at high altitudes, it seem like the compensator is not working properly.

I was near Vail CO and I was out running everything on the road with my '80 300SD but there was no visable smoke. How sweet it was: Third gear, 4000RPM, 60 MPH. Even V8s couldn't keep up with me because of the turbocharger pushing more air into my engine

P E H.

oldsouth · #8 03-26-2002, 12:08 PM

I was proud of mine also when at highway speeds. Ran great. But at low speeds or idle, it looked like it was on fire. Nobody got close at the redlights.

P.E.Haiges · #9 03-26-2002, 12:09 PM

Oldsouth,

Sorry I don't know anything about any computer controlled engines gas or Diesel. I'm from the old school.

If you are billowing smoke at high altitudes, it seem like the compensator is not working properly.

I was near Vail CO and I was out running everything on the road with my '80 300SD but there was no visable smoke. How sweet it was: Third gear, 4000RPM, 60 MPH. Even V8s couldn't keep up with me because of the turbocharger pushing more air into my engine

P E H.

daddiojiggy · #10 03-26-2002, 08:38 PM

your right about m.b. not putting any manuals out for us!i looked high and low 'til a mechanic friend told me about ALLDATA.COM.i have a 140 as well and i can't tell you how helpful this sight has been.the way i look at it is even if i can't do the repair ,by going to the site i'll at least understand what is involved.check it out -you won't regret it

oldsouth · #11 03-26-2002, 09:11 PM

Thanks young north but I am already a subscriber. Better than nothing but I find it kinda shallow.

daddiojiggy · #12 03-26-2002, 09:49 PM

i suppose it is shallow but it's all i know that is out there.does anybody else know have any ideas?thereis one thing....................
if your a member of mb's club(mbca.org),they have a classified section and you can get our model on MICROFICHE.you then can go to e-bay and buy a reader.good luck!!!let me know what happens

oldsouth · #13 03-26-2002, 09:56 PM

Really! I was not aware of that. May be worth looking into.

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