× Die Bosch D-Jetronic war 1967 die erste Großserien elektronische Einspritzung der Welt. - Bosch's D-Jetronic was the first mass-production electronic fuel injection.

D-Jetronic Problem!!!!!

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12 Nov 2022 05:11 #18642
von dnadanny1
D-Jetronic Problem!!!!! wurde erstellt von dnadanny1
Hi there. Hope you all ell. My car is Mercedes Benz V8 3.5 D-Jetronic. The symptoms are as follows:
1) The car is cranking but could not be started
2) 4,8,2,7 cylinder injectors fuel spraying volume is very high when cranking
3) 1,5,6,3 cylinder injectors has no fuel spraying volume when cranking

That's why i did a quick checking:
1) when ignition on, sometimes 4,8 cylinder injectors has a little fuel coming out, sometimes 7,2 cylinder injectors has a little fuel coming out
2) when ignition on,1,5,6,3 cylinder injectors has no fuel coming out

And then i tried to further measure the trigger point:
1) For pin14 - pin12, the close angle is 159, the open angel is 201 
2) For pin21 - pin12, the close angle is 150, the open angel is 210
3) For pin22 - pin12, the close angle is 156, the open angel is 204
4) For pin13 - pin12, the close angle is 150, the open angel is 210

And then i tried to further measure the ECU wire:
1) For pin11 to ground, it is good and normal
2) For pin16 and pin24 to earth, they both have 11.9v when IGN ON 
3) For pin18 to earth, it has 9.6v when cranking

And then i tried to further measure fuel pressure:
1) when cranking, it has 2.0bar 
2) IGN OFF, it has 0.1 bar

And then i tried to further measure the injectors
1) when IGN OFF, for pin3/4/5/6 to earth, they all have s 2.2 ohm
2) when IGN ON, for pin3/4/5/6 to earth, they all have s 7.1 ohm

And then i tried to further measure the temperature sensor:
1) for pin1 to ground, it has 191 ohm when the temperature is 25 degree Celsius

And then i tried to further measure the coolant temperature sensor:
1) for pin23 o ground, it has 2.0k ohm when the temperature is 25 degree Celsius

The questions from me are:
1) what are the causes for the injectors having small or large fuel spraying volume? is it because of the close angle or open angle?
2) The increase of fuel spraying volume is caused by smaller or larger open/ close angle? 

3) Should I use Norberts gauge adjustment tool or angle meter for better measurement of the close/ open angle?

Thanks in advance for your help! Really appreciate any of your comment!

Best regards,
Danny Cho

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12 Nov 2022 11:21 - 12 Nov 2022 11:23 #18643
von Dr-DJet Europe Mercedes-Benz R107 450 SL, Mercedes-Benz W111 280 SE Cabrio
Dr-DJet antwortete auf D-Jetronic Problem!!!!!
Hi Danny Cho,

you measured a lot. I will try to comment below:
  1. Your trigger points seem to be working and connected to ECU.
  2. Your battery voltage is pretty low. A good battery has 12.6 V and it charged with 14.4 V. 11.5 V is the minimum for our ECU.
  3. I cannot explain the varying injector resistance. Verify cables, ground points and resistance of injectors on connector.
  4. You loose fuel pressure too quickly. Check where you loose that. Fuel pump non.return valve, hoses, injectors, pressure regulator, cold start valve.
  5. Verify temperature sensors with graph in chapter 13
  6. Injector opening time cannot be adjusted by dwell of Trigger points. ECU only triggers on fall of signal, width is not analyzed[/url]
  7. Injector resistance would have an influence on timing.[/url]

Viele Schraubergrüße - best regards, Dr-DJet Volker
Mercedes-Benz 107 SL/C in der SLpedia Sternzeit 107

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Letzte Änderung: 12 Nov 2022 11:23 von Dr-DJet.

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  • nordfisch
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12 Nov 2022 23:38 - 12 Nov 2022 23:38 #18648
von nordfisch Europe Opel Diplomat 2.8 E
nordfisch antwortete auf D-Jetronic Problem!!!!!
Hi Danny Cho,
I didn't understand one thing in full:
- Do the injectors 4,8,2,7 leak fuel when only ignition is on, the engine not cranking?

If so, you should remove the electrical plugs and test them again to be sure it's not an electrical problem.
If the injectors are still leaking they can't hold the fuel pressure, they have to be cleaned or replaced.

Regards
Norbert
 
Letzte Änderung: 12 Nov 2022 23:38 von nordfisch.

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15 Nov 2022 01:42 #18658
von dnadanny1
dnadanny1 antwortete auf D-Jetronic Problem!!!!!
Thanks both of your replies! I have tried to block fuel-return hose to prevent fuel from returning to the fuel tank, but the fuel pressure still drops to zero. I also tried to block the fuel-supply hose, the fuel pressure still drops to zero. Therefore, it means when ignition on, spraying fuel of 4,8 or 7,2 injectors causes the problem. It also means when I remove the electric connector of 4,8,7,2 injector, the fuel pressure can keep at the level of 2.0bar, no matter ignition on or off. 

The issues right now are:
1) When ignition on, 4,8 or 7,2 injectors are getting ecu signal. Is it normal? If not, what are the potential causes?
2) Should I measure at the ecu connector with ecu disconnected or connected, if I want to know the resistance of injectors?

Thanks again for your kind help!

Best regards,
Danny Cho      

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15 Nov 2022 01:49 #18659
von Dr-DJet Europe Mercedes-Benz R107 450 SL, Mercedes-Benz W111 280 SE Cabrio
Dr-DJet antwortete auf D-Jetronic Problem!!!!!
Hi Danny,

no injectors should not open just by ignition on. That sound like an ECU problem. Your measuring should be with removed ECU in wiring harness connector.

Viele Schraubergrüße - best regards, Dr-DJet Volker
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20 Nov 2022 05:41 #18660
von dnadanny1
dnadanny1 antwortete auf D-Jetronic Problem!!!!!
Thanks for your help! I have learned a lot from this forum. I have followed the instruction in the chapter 13 per your suggestion, but did not find out any issue/ error.

For next step, I think I need to check ECU. May I know how can I confirm the ECU is faulty? If it is faulty, could you introduce reputable mechanics to me for repairing?

For my knowledge, I would like to know if the trigger fiber rubber cam is severe damaged/ worn, will it have the same symptoms/ performance that I am having right now? If not, what would be the symptoms?

The reason why I ask the above question is that the trigger point is always the cause of over-/ under-fuel injection for the my car,which make the car cranking, but not running. Every time I change the trigger point, the car can start running. After reading and learning from your forum, I learnt that it is not necessary to change the trigger point every time. I learnt how to use the adjusting tool by Norbert Fischer, so this time I would like to try adjusting instead of changing the trigger point, but I still could not tell if it is the ECU or the trigger point being faulty.

Thanks a lot~ Have a nice weekend~

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20 Nov 2022 11:15 - 20 Nov 2022 11:16 #18661
von Dr-DJet Europe Mercedes-Benz R107 450 SL, Mercedes-Benz W111 280 SE Cabrio
Dr-DJet antwortete auf D-Jetronic Problem!!!!!
Hi Danny Cho,

Bosch itself can repair it: www.bosch-repair-service.com/en/engine-c...ronic-0280002004001/ . Technically I could also do it but I am not a service provider and I cannot deal with import, customs, export ...

YOu had measured your trigger points to be all on same level. That is why I do not understand your question. What changes when you remove and reinstall them?

Viele Schraubergrüße - best regards, Dr-DJet Volker
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Letzte Änderung: 20 Nov 2022 11:16 von Dr-DJet.

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26 Nov 2022 03:48 #18697
von dnadanny1
dnadanny1 antwortete auf D-Jetronic Problem!!!!!
After days of checking, I think it is the issue of the trigger point rather than the ECU, which is aligned with your helpful article.

Since I only know "open/close" of the trigger point, when you say "dwell of the trigger point" or "fall of the signal", could you please further explain on what you mean by dwell or fall? Thanks

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26 Nov 2022 09:11 #18698
von Dr-DJet Europe Mercedes-Benz R107 450 SL, Mercedes-Benz W111 280 SE Cabrio
Dr-DJet antwortete auf D-Jetronic Problem!!!!!
hi Danny Cho,

dwell is the degree that the contact is closed. 360° being one full turn. Same definition as in ignition contact. SO you can use a dwell meter to measure.

Viele Schraubergrüße - best regards, Dr-DJet Volker
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03 Dez 2022 05:01 #18717
von dnadanny1
dnadanny1 antwortete auf D-Jetronic Problem!!!!!
Thanks for your advice and help! I finally changed a new trigger (for 400 euro), and I was so happy that the car can start very quickly. After a few days of driving (~100km mileage), one day when I tried to start the car, the car could not start this time. Therefore, I took out the 8 spark plugs, and i found that 4,8,7,2 spark plugs are wet and full of fuel, but 1,5,3,6 are dry then I dried the spark plugs and put it back, but the car still could not start. I took out the spark plugs again, still 4,8,7,2 spark plugs are wet and full of fuel, but 1,5,3,6 are dry. Therefore, I dried the spark plugs, put them back, and I disconnected the injector electric connector of 4,8,7,2, the car could start this time.

I have a question:
Why the car can start without injector electric connector of 4,8,7,2, but could not start with injector electric connector of 4,8,7,2 on? Either way the 4,8,7,2 cylinder should not work. My hypothesis is that when the injector electric connectors of 4,8,7,2 are on, it stool the electric signal from 1,5,3,6. :)))

What should be the next-step to troubleshoot the issue? Thanks!

Would like to download knowledge from you all experts. Hope you have a great weekend ahead!

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