Help D-Jet Mercedes M110 280CE

Hi Mads,

as I am on vacation, I did not follow this discussion. Yes it looks like, your ignition -as in 90% of injection or carburettor problems - is the cause. How can it fail:

- Isolation problems on lines to spark plug. Run the car when it is absoluetely dark and open engine compartment. If you see lightning, you have isolation problems and the spark plug finds ways to directly short-cut to the engine without going through spark plug.
- 2 resistors before spark coil
- spark coil could have internal short-cut and thus overheat and create too little secondary voltage
- distributor cap and finger can be loose or burned
- Contact on distributor can be covered with dirt
- Did you adjust dwell and timing at 300/min and check correct timing at idle, 1500/min and vacuum adjustment?
- Do you have a Bosch service around with an old master that still has an ignition oscilloscope. Would be best to monitor what is going on.

You cannot cut off capacitor as is is directly linked to the cable form contact to ignition module. But look at the green cable. They like to get bent so much that they start to fall of.

Best reagrds,
Volker

Thank you for your help

Just tested the Resistor 1 and 2:

- Ballast Resistor 1 blue = 0,8 (should be 0,4)
- Ballast Resistor 2 silver = 0,9 (should be 0,6)

I also tested the mixture on the ECU, it runs better when i turn the screw to a richer mixture:



So i think the mixture i to lean, but i don't know why When i pull off the MAP, the mixture gets even richer, and it idles even better.

The rotor, cap, wires and spark plugs is from 2014, only run about 500 km..







Mads

Hi Mads,

it absolutely makes no sense to try to correct the ignition fault via D-Jetronic adjustment. You have to first find the reason for your ignition fault. That is why I recommended a Bosch service around you with an ignition oscilloscope (I use an old Bosch Compactest). When you habe your ignition problems fixed, you can have a totally different scenario. Ignition problems with failing cylinders will especially create problems in idle-run. The higher enigne speed is, the less you will notice such problems.

Or if you are not sure about your timing light, try another one.
90% of injection and carburettor faults are ignition problems in reality.

Sorry it's been so long time since my last update... I Actually got the car running ok now.. i don't know where the fault was. but after i adjusted the MAP sensor a bit, it runs much better, so maybe it's closer to the original adjustment now..
Is there a way i can calibrate the MAP? i was thinking there must be some spec. at eg. 1 bar pressure or something like that?

But anyway, all your help got the car running again.. thank you for that

Mads

Hi Mads,

no sorry, you cannot tune and verify your MAP sensor. Only Bosch and e.g.. me can do .