Has anyone added the ELR system to a car that did not have it stock....
 

I pulled the 2.0 liter engine out of my 1984 190d and got the 2.5 liter engine from my 1987 190d in there. The 1987 engine had the ELR system for controlling the idle.

I have the complete wiring harness from the 1987 engine and will try and graft parts of it into the 84, but I was wondering if anyone has ever done this before?

At first I will have to get the car running with that system and as far as I can tell it will default to idling at 500rpm.

You should be able to transplant the entire engine control system over no problem.

You will have 2 power feeds to your K1 OVP relay - one is switched hot to close in the relay, and the other is battery power.

It is a 201 not a 123. There is no OVP. I am not sure I need to transplant the OVP as well

I will post some pics later.

Pretty sure all you need to connect is the ring gear sensor, engine temp sensor and the IP speed control unit.

Every 201 I have ever had has an OVP. The 84 with the vacuum idle may not have one, but your 87 should have one.

Yes the 1987 has the OVP and I have that whole harness.

The OVP system started in 1985. I was surprised to not find it in the 1984.

I am not sure if I can or it is worth it to add the OVP to the 84.

There should be an adjustment screw with a lock nut on the back of the injection pump; you can use this to adjust the idle up to ~750 rpm, and not have to worry about all that ELR stuff. You would need pretty much all the electronic stuff behind the battery (computer) and probably inputs from engine speed and too much to make it worth it.

On my '87 wagon, the ELR system was flaky and gave me a really rough idle, it has been disconnected for almost a decade now, idle speed set mechanically. Of course I've got one extra cylinder, so the engine speed doesn't change much when the AC compressor is engaged, so that may bug you a bit if the engine slows down too much with the AC compressor.

There are 2 parts to the 87 EDS
EGR/ARF valve control
ELR electronic load regulation

The first part well you know what that is good for, a gummed up intake.
The second part you will probably want for the reasons Max mentioned.

You will need the computer behind the battery. There are probably 2, one is the ABS (further forward on my 124) and the other is the EDS controller.

The pieces you will need for load regulation:
- IP sensor (top of the IP)
- IP actuator (rear end of the IP)
- trimming resistor (the knob marked 1-7)
- reference resistor (on firewall on my 124)
- altitude sensor (also likely on firewall)
- OVP (red tall relay with fuse near battery)
- ring gear sensor (left rear down low on block)
- temperature sensor (middle of the head between 2 of the glow plugs)

Some of these inputs have only to do with EGR/ARF but I don't know specifically. Since you are taking the entire wiring harness might as well get the sensors as well.

- the 2 vacuum transducers and air box sensor are for the EGR/ARF control.
- in the 87 602 I believe they used pressure waste gate and a simple pressure switch that opened a valve for overboost protection like they did in the 87 603. Not like the 90+ where the EDS carried these functions too.

One other thing to consider is that you need to feed the Klima relay with a tach signal. This is derived from the EDS box. If you do not satisfy the Klima the compressor will not start. Yes you can run with it jumped, but you lose the seized compressor protection. I would not want to drive like that and have the compressor fail, shred my belt, and kill my water pump.

I don't know if they published 201 wring diagrams online. I have been looking at the 603 diagrams for my 124 to get my information. I suspect the engine management in the 87 201 is very similar to the 124. If you can't get the 201 diagram I would study the 124 diagram to see how these devices are connected.

I am not going to run the A/C system. I still have the A/C pump but I am not going to actually hook it up. I removed the hoses running to it.
(I should clarify - the pump is in place and the serpentine belt is driving it. I was not going to hook up the electrical connections)

I thought that if I do not even hook up the connection it should not be able to seize.

The condenser that I pulled was damaged and it is from 1984 - I am not sure if I would need to change the system over to the R134a. It just seems like a hassle. I have actually never had working A/C. Every car has always had it missing. Even in my 3 different w124 wagons.

Well my perspective on A/C is a little biased. It's nearly a matter of survival down here in SC. Not just for when it is stinking hot in the summer, but also for when we get rain :eek: and the dew point goes into the upper 70s and it's needed to keep the windows clear.

I do agree that if you do not engage the clutch then there should be nothing to cause the belt to seize.

I'm not sure how you would add the rack actuator to the IP, which is the one indispensable component. The air mass sensor is also a component, but it's only used to control EGR, AFAIK.

I have the '87 emissions manual, which has all the EDS diagrams. Not sure how I could post something that large, though. PM me with an e-mail address and I can try to send it as a zip file.

His 87 engine is the donor and I am assuming that he has all the required sensors intact on the donor engine. The donor's IP should be equipped with the sensor and actuator.

If he's not running A/C then he can probably get away with using none of the controls and just dial the IP to a decent idle speed.

The only downside to that approach I can see is that the EDS computer derives the tach signal. He will need at the minimum the OVP, EDS controller and ring gear sensor for a functional tach.

I'm confused about the goal here. '87 engine into an '84 body, idle speed has been mentioned, what else do you want working?

That is a fair question.

I thought that I would need the ELR system to maintain idle speed. The goal was to get that running. I still feel that is the goal.

Ideally I would like a working Tach and oil pressure, but I am thinking I may just use aftermarket gauges to achieve those.