Up here in the high desert/plains of central and eastern New Mexico, my fuel economy in my 1972 220D isn't what I'd like and the engine is smoking black a good amount, so it's running rich.

I know I'm wasting fuel so I'm wonding if subtracting one more large diameter compensation washer under the spring which pushes against the IP governor diaphragm, would effectively change my mixture?
Logically, it works in my head but I'm a bit green when it comes to diesel injector pumps.

The theory is the decreased spring pressure would allow the venturi vacuum force to pull the diaphragm more and slow down the motor at idle and throughout the range of operation. The real question is would the powerband change be linear or would it be on an increased curve? Should I even worry about questions like that since the spring force is already built in and the IP is designed around the spring force through its travel?

Since this IP doesn't have an altitude compensation mechanism, I'm hoping this easy fix is the ticket to a little better fuel mileage and less smoke.
Any advice?
I'm not going forward on this without some expert advice but I'm hoping there is some validity to my theory that it will work.

Thanks all!
Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

does your car have a throttle plate in it? perhaps your linkage is not opening it fully? there's no way it's got EGR, so I doubt it, but it's possible.
removing spacers from the ADA should reduce fueling, but so will slight screw tightening of the adjustment screw, if it's similar to 123 ADA...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I think he said no ADA.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Put a turbo on it. High altitude is one situation in which adding a turbo to an NA engine without doing anything else is useful.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

DOH! if only I would READ...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I want the engine to last. It's an OM615 so no turbos.

I'm only going to be here another six weeks but I'd like to test my theory as long as I'm not going to be completely screwing things up.

No ADA, it's just got the plain old pneumatically governed IP. In theory, reducing pressure from the governor spring would compensate for the rich mixture slightly and may help with fuel consumption by balancing the spring tension more to the thinner air. The idle is higher here because at 7000 feet the air pressure is lower and with the lower density in a column of air, the venturi vacuum can pull against the diaphragm less.

Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Putting in a Turbo with boost set to 1 psi would not harm the motor and it would restore power to stock at sea level.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Yikes, a 220D at high elevation, what does it have like under 50HP there?

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I don't know anything about your engine's injection pump, but it seems your understanding of how a diesel works is wrong. The injectors do not control O/F ratio like in a gasoline engine. A diesel runs wide-open throttle, i.e. you don't throttle the incoming air. Indeed, better to compress it (turbo). The power is controlled by how much fuel is injected. The fuel burns as fine droplets, basically fairly rich around each droplet even at low flows.

If putting out smoke, either the spray is not fine enough or you are adding too much fuel (stop pressing the pedal when you see smoke). That said, you can still get more power with black smoke coming out, just less efficient. See youtube videos of Finnish guys who boost the IP flow and spin the tires, with thick black smoke coming out the exhaust.

Chapter 07-010 in the W123 (non turbo) FSM describes not only the operation of the IP (M pump MW and M/RSF variants) but the ADA too...

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

His engine has a throttle--a butterfly valve in the intake. This was standard in many 615 and 616 engines. The vacuum produced by that throttle controls a diaphragm in the IP.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

The OM615 does have a throttle plate which controls air flow. The position of this plate controls the injection pump pneumatically by creating a vacuum with a venturi in the throttle body. Changing the amount of restricting foce on the diaphragm which controls the rack in the IP will effectively change the mixture.

No, I'm not putting a turbo on the engine. Possible or not on the OM615, it's not happening. Enough of that.

This thread is not and never has been about power output. The car has plenty of power here. It's about efficiency.

This engine does not have an ADA.
The FSM does not say anything about compensation of the governor for high altitude.

Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Your idea sounds logical to me. You want to reduce the fuel flow to the injectors, not the timing or anything else. It should be a linear power curve. You should notice slightly less power overall and less smoke/if any.

__________________
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

Sounds like overfueling. In thin air, dynamic pressure is less because air density is less. Pressure drop at venturi will be less. Shim it whatever way will fool it into thinking there is more vacuum.

Or, put a syringe on the hose that feeds the bellows, run it inside. Adjust the bellows w/ syringe for less smoke.

__________________
CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

This is what I was looking for. A corroboration of my theory.

I'll take out a spring loading washer tomorrow and do a test drive. I have a photo shoot at a high school football game so I'll have an excuse to get on the freeway and see how the top end is.

Thanks!

Phil Forrest

__________________
1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson