Help D-Jet Mercedes M110 280CE

Hi Mads,
I cant believe all your temp sensors and the MAP sensor, too are defective.
I still believe in a problem with the cable lugs.

The sensor 0 280 100 111 is 'type III' and much more solid than the other types.
Therefor it is avaible in used condition at a much lower price than the others. The risk in getting a defectice one is not too high.

But perhaps Volker can sell you a MAP sensor that really works 'with guarantee' cause he checks every part most intensive,

Repairing the sensor means opening it, maybe the coil is defective in total maybe can be repaired.
But then one must reassemble the sensor correctly - great risk it doesn't hold vacuum after that.
Then it must be readjusted - no other hobbyist than Volker can do this, as far I know.
Read about it at the D-Jetronic-Compendium here...

My advice: Buy another MAP-sensor, keep the defective one - one day it may be repaired.
Think you want to drive the car...

Regards
Norbert

Did the test directly at the connector, without the plug.. Can do a video on the test..

Mads

Hi Mads,
we like videos...

It would be most interesting in which way all these components got damaged --- still can't believe all sensors are defective

And the motor ran before, or are you overhauling the car you got in non-working condition?

Regards
Norbert

The car has not been driven a lot, because it runs pretty bad did an ekstra test today, the MAP secondary coil is still bad, when i test directly on the MAP.

Primary

Secondary


The air temp sensor is also dead i cant figure out what sensor is the coolant senso, its only the one in the mittle that's giving a reading when i messure the ohm..


But it's actually a pretty nice car, good shape.. Seen here with my 1971 350SL:



Mads

Hi Mads,

if the picture is correct, then you measure wrongly! Your multimeter is in range 200 Ohm when you try to measure a 360 Ohm resistance. No wonder it shows "1 ." indicating above range. Switch it to 2000 Ohm before you measure secondary coil. And please switch to 2000k when you measure against car ground as second test on primary and secondary coil.

Sorry, i'm pretty stupid The secondary coil is showing 361...
But now i don't a solution to my problem BAck to testing again

Mads..

Hi Mads,

as long as I can see the mistake from a simple picture, I can help There are also multimeters with Auto-Range.

You should now repeat all your tests from scratch at the connector of ECU. You will see much less faults, I am sure. I would also recommend you to buy Bosch workshop manual M110/M114. But I just see that it is only available in German , I am sorry.

Hi Mads,
I used such an auto-range-multimeter Volker noticed yesterday for the first time.
This is quite comfortable - and your SL is equipped with D-Jetronic, too. Maybe an investition that makes sense for the future.

The sensors in your car are (your photo, from left to right):
- heat indicator (instrument board)
- thermo-time-switch (to be measured in nspecial way, see chapter 9.2 in Volkers D-Jet-Compendium)
- coolant sensor

Regards
Norbert

Did all the test again, seems like there is a shortcut from pin 7 to 11, i'm getting 368 ohm..
Any idea where the shortcut could be?

Mads

Hi Mads,

did you measure pins 7 to 11 with ECU disconnected? If you have a shortcut then, it means either

1. a cabling problem (pin 7 somehow connects to ground)
2. an internal shortcut in MAP sensor to ground - which I consider low probability

Disconnect MAP sensor and measeue 7 to ground again. If it is still there, it is 1. If it is gone, measure pin 7 of disconnected MAP sensor versus MAP sesnor housing. If you have shortcut there, replace MAP sensor.

Did the first test with ECU connected. The fault is not there when i disconnect the ECU.
When i measure on the MAP pin 7 - ground there is no fault..

Mads

Also did a smalle video of what happens when i connect the MAP, it is very hard to keep the engine running..

Mads

Hi Mads,

was your idle-run contact on pin 17 closed when you did the video? If no, MAP sensor signals full-load to ECU and enriches mixture. That would then mean too little fuel. Checked fuel pressure?

I have just tested pin 17-12. (battery disconnected, ECU disconnected)

Throttle valve minimal = infinente ohm
Throttle valve max = infinente ohm

Should i do the test with ECU + battery connected ?
Thank you for your helt Volker..
Mads

No Mads,

have a look at my maintenance article how to adjust idle-run contact and fuel pressure.

Hi Mads,
the short-circuit (about 360 Ohms) between Pins 7 and 11 sounds familiar to me.

I once also measured such a value with an EFAW228 (special testing device from Bosch for D-Jetronic) on a bad-running car.

The reason for this phaenomenon may be the special internal or external wiring of the five-poled throttle-valve switch your car also has built in.
I didn't check this up to this time... no time to check it right now.

But he reason was in true a defective throttle valve-switch with a non contacting internal feeler-contact (the outer one).

Please remove your throttle-valve-switch and take off the cover. The switch is not so easy to understand and measure in built-out-condition because of the multi-functional switch and feelers in there, but you can clean it internal and check the conductor pathes, the feelers, the switch.and the feelers towards the connectors. Don't disadjust anything, just clean it carefully.

Then remount and readjust it following the instructions here on the page.

Maybe we found the reason for your problems...

Best would be to send some photos of the opened switch.

Regards
Norbert

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