Help D-Jet Mercedes M110 280CE

Have taken the TPS off, it seems to be fine

Mads

Hi Mads,
it really looks o.k.
Please clean it, the sleeve points also. There is one more sleeve point hidden under the inner finger.

The throttle valve switch I had the problems with was in even better condition than yours, but yours looks fine, indeed.
The problem was grease between sleeve points and the conductor pathes. Don't grease or oil it.
The electrical current at this part is very low, and oil can insulate the points.

Please reassemble it, adjust it and then...
no other way than repeatng all the measurements - the complete list, all measurements.

Only if everything else is o.k. the ECU remains as being the defective part.
Only Volker can check and repair this, and he is on holidays...

Stay tuned, we will find the reason(s) for your car running so bad.

- Did you check the camshaft, the engine timing... maybe there ist another problem. D-Jetronic is often seen as being defective, when other motor-components are failing.

Regards
Norbert

Did a few test after work today. Fuel pressure is steady around 2 bar.. is it the right place i messure the pressure ? took of the cold start supply..


I actually got the car to run with the MAP connected, even though its still a bit rough...like it cuts out ihe ignition..


Then i did a test with the timing light on the coil, and i confirms that it cut's off the ignition.. Don't know what i can conclude out of that?


Mads

Hi Mads,
- This is the easiest way to connect the manometer correctly, just at the hose towards the cold start valve.


Seems to be a problem at the ignition, really.
This is an ignition driven by a traditional contact breaker with an ignition control module.

I can't help you with the control module, but with the other parts.

- I don't believe the ignition coil is bad.

This motor runs like my own straight 6 when 2 cylinders are 'missing'. Did you check disconnecting the cylinders one by one has an effect at any cylinder?

I saw on your photo:
- The ignition cable set seems to be replaced with aftermarket parts. Those parts are often reported not being reliable. The cable out of the ignition coil looks to be hard-bended, this might cause a break inside when these are graphite-filled wires.
Please measure the electrical resistance of each lead to ensure they are o.k.
The interrupts in ignition may also be caused by defects far away from the coil.

- The green cable out of the distributor towards the control module seems to be in bad condition. Check it.

- Check the resistor block near the ignition coil. Nothing loose ore broken?

- Take off the distributor cap. Are there any marks of misfiring ignition inside?

- Is a speed-limiter-rotor still mounted? Then fix the weight inside so it can't break ignition anymore (for testing) or replace it by a 'normal' one. check the rotor for burns and measure the resistance from the middle contact to the outside. resistance should be about 5kΩ.

- clean the breaker contacts with non-abrasive and non-fluffing material using spiritus, Is the pressure of the spring still o.k.?

- If there is MP capacitor in- or outside the distributor? You can cut it off and remove it, it's not needed but could cause trouble.

- Did you replace the spark plugs, how do they look?

No more at this time... others may have more or other ideas.

Regards
Norbert

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