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.

MB 350 SL low power

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28 Jan 2025 23:52 #22751 by Gerbido2000
MB 350 SL low power was created by Gerbido2000
good evening dear friends, my MB 350 SL loses power when I reach 4000-4500 rpm and does not increase. 
The engine has had major extraordinary maintenance, cylinders, pistons, MAP sensor, trigger point, ignition cables, ECU, distribution, and more.now,the engine has 11000 km.
only the injectors have not had any maintenance, but they appear to be in good condition.
what could be the problem?
whit the rotary button on the ECU i can increase the fuel?
thank you for your precious help and best regards.

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28 Jan 2025 23:57 #22752 by Dr-DJet
Replied by Dr-DJet on topic MB 350 SL low power
Hi,

I would start with ignition first. Does ignition timing fit and do you have right components installed. Then it would be great if you could have a measurement of ignition signals to verify they are all there and in full power.

Then we would continue to search in D-Jetronic. ECU rheostat should not be active outside of idle.
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107
Workshops D-Jetronic 20.9.(ER)

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29 Jan 2025 00:18 #22753 by Gerbido2000
Replied by Gerbido2000 on topic MB 350 SL low power
Good evening Volker, the order of ignition seems correct to me, however I will try to make a new check.
This problem is old and manifested from the first start after extraordinary maintenance.The engine up to 4500 rpm works wonderfully.
Also I add the motor wiring is new.
Thank you for your help.

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29 Jan 2025 00:39 #22754 by nordfisch
Replied by nordfisch on topic MB 350 SL low power
Hi,
you forgot to sign your posting with your first name...

In addition to what Volker wrote: You find the values to be verified here: www.startekinfo.com/service/download-doc.../M117_45/075-500.pdf
Check not only at idle, but at 1500 and 3000 rpm too...

There is a speed-limiter-finger in the distributor. This could be misadjusted or defective.

Regards
Norbert

edit: The ECU-knob is only for adjusting CO at idle. It is active only at idle.

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29 Jan 2025 01:07 #22755 by Gerbido2000
Replied by Gerbido2000 on topic MB 350 SL low power
Many thanks Norbert,
My name is Marco,
Greetings from Italy

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29 Jan 2025 01:15 #22756 by Gerbido2000
Replied by Gerbido2000 on topic MB 350 SL low power
Hello Norbert, I can not understand the detail of the speed limiter in the distributor.... is it related to the rotor?
Thank you

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29 Jan 2025 08:45 #22757 by nordfisch
Replied by nordfisch on topic MB 350 SL low power
Yes, Marco -
the Rotor is the speed-limiter. But maybe it was replaced by a rotor without this feature.

Regards
Norbert

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29 Jan 2025 10:15 #22759 by Dr-DJet
Replied by Dr-DJet on topic MB 350 SL low power
Hi Marco,

yes there is a rpm limiter in rotor. Normally at 6500 /min. It can misfunction. However frist check that you have correct ignition distributor and that it changes ignition timing correctly at idle, 1500 and 3000 rpm. You can replace your finger with the early version without rpm limiter. If your engine then turns higher you knwo the mistake.
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107
Workshops D-Jetronic 20.9.(ER)

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29 Jan 2025 10:26 #22760 by Dr-DJet
Replied by Dr-DJet on topic MB 350 SL low power
Hi Marco,

if rotor was the problem it would be like hitting a wall at 4500 rpm. Sudden loss of power as igntion is shortcut. Or is power slowly decreasing and you just cannot go faster as engine has now power. Downhill you can go to higher rpm in such a case.
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107
Workshops D-Jetronic 20.9.(ER)

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29 Jan 2025 22:22 #22761 by Gerbido2000
Replied by Gerbido2000 on topic MB 350 SL low power
good evening dear friends, I am happy to announce that I have solved most of the problem.
the vacuum connection pipe that connects the diaphragm regulator of the distributor to the intake manifold was of the wrong material and size. I replaced it with the original 4 mm rigid pipe. now the engine reaches 5900 rpm.
furthermore, I noticed that the air filter fixing systems were broken and I replaced them.
I will also replace the intake air filter seal, it seems old and hard to me.
Many thanks for your precious help.
Mark,
city ​​Piacenza, Italy

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29 Jan 2025 22:30 #22762 by Gerbido2000
Replied by Gerbido2000 on topic MB 350 SL low power
Hi friends, I ask please if you know the BOSCH or MB identification number of the optimal rotor for my engine 116982? my car dates back to September 1971, the engine has number 00287... approximately... however one of the first.
Thank you

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29 Jan 2025 22:53 - 29 Jan 2025 23:07 #22763 by nordfisch
Replied by nordfisch on topic MB 350 SL low power
Hi Marco,
congratulations... as often, a non-D-Jetronic-related problem again.

You will find your question answered here: jetronic.org/en/d-jetronic/mb-components

Regards
Norbert

edit: As I found out there, till 9/1971 no limiter was installed... You could install it as a 'security extra' , but it is quite expensive.
Last edit: 29 Jan 2025 23:07 by nordfisch.
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29 Jan 2025 23:46 #22764 by Gerbido2000
Replied by Gerbido2000 on topic MB 350 SL low power
the D-Jetronic is a refined and prestigious system and only for true connoisseurs.
thank you friends for your help.

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30 Jan 2025 00:09 #22765 by Dr-DJet
Replied by Dr-DJet on topic MB 350 SL low power
Hi Gerbidio,

your engine should reach 6500 rpm before rotor shortcuts ignition. How does your rotor look like. You can get the rotor limiting to 6500 rpm from MB. Otherwise it is hard to get. If you use the 177 rotor without rpm limit, it could be that you overturn engine especially when playing with gas in garage.

It you run your engine carefully you can take the risk to use rotor without rpm limit.
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107
Workshops D-Jetronic 20.9.(ER)

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30 Jan 2025 02:23 #22766 by Gerbido2000
Replied by Gerbido2000 on topic MB 350 SL low power
Many Thanks Volker.

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