Accurate instrumentation possible on a diesel?

[AndrzejM]

So why don't you share the diagram? ;-)

[cRiPpLe_rOoStEr]

Originally Posted by oldbeaver

In a Mercedes OM 603 engine, there is a EDS control unit that is supposed to control the amount of diesel to be inyected by injection pump.

If it was compliant with OBD-2, might work with MPGuino and other similar devices

[UFO]

I use a scangauge II. It becomes way off (from 2 to 15 mpg wrong over a tank) if I implement my EGR delete, go on a road trip, change biodiesel concentration, or make any significant change in driving technique.

Fortunately, I can calibrate it for B100, no EGR, and with my driving techniques fairly settled it is a useful tool for monitoring my daily commute over a tank, including some non-commuting driving over the weekends. I can make seasonable adjustments to maintain reasonable accuracy from spring to fall with B100 fuel.

Yeah, it'd be nice to have real fuel flow measurement.

[oldbeaver]

Hello guys,

The Mercedes 300D turbo of 1993, on a W124 chassis, has the follwing Electronic Diesel Injection Diagram:


As you can see, there are six electric / electronic incoming signals to the injection control unit.

Can we take advantage of them to make a real time mileage monitor?

OldBeaver

[AndrzejM]

Can't see the diagram

[oldbeaver]

Originally Posted by AndrzejM

Can't see the diagram

I couldn´t see it also, at first.

I found the way to allow it to be seen: see it below:

OldBeaver

[oldbeaver]

AndrzejM, OldBeaver (myself) and others are long time seeking how to use MPGuino in an old diesel, like a Mercedes from 1987 to 1995.

One of the signals to be used is VSS. One step forward would be to find an easy point in the car where one can intercept this signal in the cleanest and safest posible way.

As we talked with AndrzejM, the other signals has to be taken from the injection system. The question is how to get them easily, to conduct them to the cabin to be processed.

Maybe the test terminals may be useful for this purpose. At least, rpm can be taken there.

Does anyone know where to intercept the effector signals from the ECU, for example? I am talking about the physical spot in the car and the practical electronic way to do it. Not just the place in the EDS diagram.

OldBeaver

[AndrzejM]

I think the best way would be to hook up to the back side of ECU plug or plug connected to the injection pump. It will be easier to find the right cable connected to the second place. Fewer connections, that's for sure

[oldbeaver]

Originally Posted by AndrzejM

I think the best way would be to hook up to the back side of ECU plug or plug connected to the injection pump. It will be easier to find the right cable connected to the second place. Fewer connections, that's for sure

I agree. The ECU harness is more complicated. And I would prefer not to touch it.

EDS Inputs to this system are:

Voltage supply via OVP relay (K1) - overload protection relay I suppose
Engine speed via speed sensor (L3) - rpm?
Coolant temperature via sensor (B11/4)
IP control rod travel via sensor (L7) - rack position?
Air quantity via AFM (B2/1)
Manifold (boost) pressure via OVP relay (K1) - useful for real time fuel estimation?
Barometric pressure via sensor (B18)
Base circuit resistance via reference resistor (R18/2)
Resistance trim via ELR knob (R18/1) - regulable fix resistance I think

Outputs are:
Variable control voltage to the ELR actuator (Y22)
Voltage to VAC transducer (Y31) and on to the ARF valve (Y31/1)
Connection to test connector diagnostic block

Basicaly, the fuel injected is governed vía ELR actuator in the back side of the injection pump, where more voltage means more fuel and less voltage means less fuel. Very useful information.

To me is very clear that ELR controls fuel injected. You want to combine it with the rack position sensor signal. Question: Is it L7?

Second, I suppose this voltage controls VAC transducer (Y31) which is the effector for .... what? The turbo somehow?

I will try lo locate all this elements in the engine compartment next to the injection pump after I recover my car, hopefully tomorrow.

Comments, enlightments?

Oldbeaver

[AndrzejM]

Originally Posted by oldbeaver

Basicaly, the fuel injected is governed vía ELR actuator in the back side of the injection pump, where more voltage means more fuel and less voltage means less fuel. Very useful information.

To me is very clear that ELR controls fuel injected. You want to combine it with the rack position sensor signal. Question: Is it L7?

Second, I suppose this voltage controls VAC transducer (Y31) which is the effector for .... what? The turbo somehow?

Your pump is controlled by two factors:
1. gas pedal linkage - it's setting up rack position - thus main fuel dosage
2. ELR signal - it's changing by some percentage fuel dose to meet value counted by ECU, based on all the sensors

So you have to know rack position adt its offset by ELR signal, then you have the exact fuel dose. Combining that with rpm signal you have the exact moments when you have to measure rack position and offset. Lets call that a trigger signal. And finally combining that with VSS signal will give you FE.

And the other question about Y31 - I presume that's a valve for EGR