Matching ECU with MAP

I am new to the forum, and glad to have found you. I am changing a 1968 111 Mercedes from a 6 cylinder motor to an 8 cylinder. The motor that I am putting in the car is a 116.980 motor. I need to purchase an ECU and MAP for the motor. I saw in your forum that the electronics inside the various ECUs are the same (0280002001, 0280002002, 0280002003, ...2004, ...2005). I saw that the correct MAP for my engine is 0280100012. Are there any other MAPs that will work for my application?

Hi unknown guest,

when changing to M116.980 you need an 0 280 002 001 or 0 280 002 004 ECU. A 0 280 002 007 would also work but you would not be able to fix it. The other forementioned ECUs are different electronics and you cannot use them. You can check those components from appendix A of my D-Jetronic compendium.

And I am afraid that there is only this single MAP sensor fitting that engine.

What you also need: Engine wiring harness for W111, Plate to fix ECU and relais and an automatic gear box fitting this engine. However if we talk of a W111 280 SE Coupe or Convertible: Engine and gear box will not fit the tunnel. That car was modified to habe a wider tunnel in September 1969. At that time it also got the lower grill.

Thank you, that is very helpful. I have the new wiring harness, correct automatic transmission, correct differential. I was unaware of the tunnel change, so I guess I will be making a modification to that as well. One more quick question unrelated to that car. I have a 1970 111 3.5 that when i start it, it dies after about 2 seconds. Any suggestion as to where to start diagnosing that? I have a very limited understanding of the DJet system. It runs very smoothly for the 2 seconds, then dies. Thoughts?

Hi Julian (is that your first name?),

changing that tunnel? You do not know what that means! I run a W111 280 SE Convertible from Florida myself. And I once considered swapping the engine with a European 450 engine. Bur replacing the tunnel with the wider version of the 8-cylinder cars after September 1969 is a tremendous change to car structure. I would not recommend it.

If your other car runs for 2 seconds only, it is either by cold start valve once or by the starting signal to fuel pump and then dying as ECU sees no trigger impulses. Can be due to worn trigger contacts or cable problems.

It could be difficult to find the ECU and MAP sensor in the US. All other MB cars (other than W111 and early W109) in the US run the 450 US engine with 0 280 002 005 ECU and 0 280 100 100 MAP sensor. They do not fit the M116.980 engine. If you cannot find any component in the US contact me again here. And please also check that your engine has the yellow injectors and do not forget the rubber boot over the ECU when mounting it.

Can you elaborate on my problem that the car runs for 2 seconds and then dies? What should I check on the Cold Start valve? And where does the ECU get the trigger impulses? I will go and start reading about the cold start valve in the forum.

Hi Julian,

thermo time switch opens (depending on coolant temperature) cold start valve and fllods intake manifold with fuel. This happens only once or twice as thermo time switch is heated up by electrical current. Engine can start and run on this fuel for a short time.

Additionaly ECU recives a signal for starting on pin 18 and thus starts the fuel pump. If there are no signals from trigger contacts after cranking the engine, ECU switches off fuel pump immediately. So the engine can definitely start without operating trigger points but cannot continue to run.