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.

Slight mis-fire at partial throttle...until I disconnect air temperature sensor

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
Mehr
26 Apr. 2024 18:24 #21325 von Dr-DJet
Dr-DJet antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Hi,

resistance does not change over vacuum. It is always the same. Transformation of input signals from ECU changes. That is why it is also called VLT - variable linear transformer.
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)

Dieses Bild ist für Gäste verborgen.
Bitte anmelden oder registrieren um das Bild zu sehen.

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

  • RussellWithABenz
  • Autor
  • Offline
  • Frischling
  • Frischling
Mehr
26 Apr. 2024 18:43 - 26 Apr. 2024 19:11 #21327 von RussellWithABenz
RussellWithABenz antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Understood that the vacuum has no effect on the sensor. The testing I did was in different temperature water and I saw the resistance change. I matched that with a chart (that I likely found here :) ) and it seemed within reasonable spec.

The popping when I re-connect seems to be throughout the throttle, not just when slightly opened. It also seems to idle a bit more roughly. All of that goes away when I disconnect the incoming air temperature sensor on the air filter intake.
Letzte Änderung: 26 Apr. 2024 19:11 von RussellWithABenz.

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
Mehr
26 Apr. 2024 20:03 #21328 von Dr-DJet
Dr-DJet antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Hi,

that means you engine runs slightly too lean. Sensor removal increases mixture on warm engine by 10-20% . That is of course not a real solution. You need to find out what is wrong. Exhaust gas measurement per cyl might give a good hint.
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)

Dieses Bild ist für Gäste verborgen.
Bitte anmelden oder registrieren um das Bild zu sehen.

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

Mehr
29 Mai 2024 02:23 #21524 von Samuel
Samuel antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
I have the same problem with my Citroen DS 23 IE.
Exhaust CO is 2.8% with the air temperature sensor disconnected.

Fuel pressure is 30 PSI with engine running. With ignition only on, the highest fuel pressure is 22 PSI, even after a few on/off ignition cycles. The fuel pump is original to the car (51 years old).

I did turn the knob on the ECU 6 clicks clockwise, but that didn't make a difference.

Could it be a fuel volume issue?

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

Mehr
29 Mai 2024 04:21 #21525 von Samuel
Samuel antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
As a follow up question...

Is the only systematic way to enrich the fuel mixture by turning the knob on the CEU clockwise?

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
Mehr
29 Mai 2024 08:29 #21526 von Dr-DJet
Dr-DJet antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Hi,

I do not consider turning rheostat on ECU by 6 clicks a systematic approach. Please remember that it only affects idle-run CO, nothing else.

It is mainly ECU and MAP sensor that really affect mixture. But they need sensors to reply correctly and they need a vacuum tight manifold, working injectors ...
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)

Dieses Bild ist für Gäste verborgen.
Bitte anmelden oder registrieren um das Bild zu sehen.

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

Mehr
29 Mai 2024 11:15 #21527 von nordfisch
nordfisch antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Hi Samuel,
your car should have a fuel-filter that looks like a box. This should be replaced quite often...
Did you check it?

Regards
Norbert

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

Mehr
29 Mai 2024 17:16 #21529 von Samuel
Samuel antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
I tested the MAP sensor (both vacuum and resistance) and it passed ok. I also dis a smoke test for leaks... none was found!

I have not tested the injectors, as it is a pain to remove them from my particular car (Citroen DS). But I would think that if there is a problem with the injectors it would manifest itself at all times, right?

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

Mehr
29 Mai 2024 17:18 #21530 von Samuel
Samuel antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Thank you Norbert,

Yes, I replaced the fuel filter last year, but the fuel pump is original and is now over 51 years old.

What are the options available for a replacement fuel pump?
Best
Samuel

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

  • RussellWithABenz
  • Autor
  • Offline
  • Frischling
  • Frischling
Mehr
29 Mai 2024 17:38 - 29 Mai 2024 17:40 #21531 von RussellWithABenz
RussellWithABenz antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
I've been waiting until I get to a computer to properly respond.  Glad to see all the Jetronic interest! The people on this site have been incredibly helpful over the years.

I do not have the expertise of some of those that contribute, but I do have more years than I'd care to mention of trial and error on my 73 450SL.  Some thoughts about recent posts:
  • As someone else pointed out, the computer dial only affects idle mixture so if your problem is above idle than it is something else.
  • If you've got 51 years on a fuel pump I think it can be honorably discharged by now.  Keeping pressure is different than providing volume.  There is a test somewhere (xx ML in yy seconds) that may help prove if that is not the problem, but if a new fuel pump is available I don't think it would be a bad thing to replace.  That is a poke-and-hope, but I saw significant gains after a fuel pump replace (Bosch fuel pump, but it is a newer flavor....dunno if it will work for the Citroen, but if the JetTronic is the same I would think so?) 
  • I've gotten my injectors re-built, but didn't see much of a change.
  • I had my entire engine wiring harness re-built and that provided significant improvement.  If the computer is getting bad signals, for whatever reason, then it will respond badly. Dunno if that is an option for you.
  • Many of the changes, combined, have significantly improved the operation.  The last time I had it out there was very little bad behavior and the temperature sensor was plugged in.  
  • I'm still going to hunt for vacuum leaks.  While the tanks will hold for a while, so my door and trunk locks work now, but that doesn't mean there isn't a leak before the tank(s).
  • I still have a horrendous hot-start problem.  It is notorious amongst the older 450's, but mine seems worse that I would expect.  Sometimes, I just leave my hood propped open when I park.
  • - I'm still chasing gremlins...but they are smaller.
Letzte Änderung: 29 Mai 2024 17:40 von RussellWithABenz.

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
Mehr
29 Mai 2024 18:34 #21533 von Dr-DJet
Dr-DJet antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Hi,

I recommend to keep original Bosch D-Jetronic fuel pump as long as it works and does not leak and of course supply enough fuel. I do that myself. I would not follow our unknown friend x046866x. Please sign by firstname as it is usual here. And if you want to discuss your 450, please open a separate thread and let us not mix this one.

 
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)

Dieses Bild ist für Gäste verborgen.
Bitte anmelden oder registrieren um das Bild zu sehen.

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

  • RussellWithABenz
  • Autor
  • Offline
  • Frischling
  • Frischling
Mehr
29 Mai 2024 18:49 #21534 von RussellWithABenz
RussellWithABenz antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Apologies for weird username.  That was a poor choice when I registered and I'm contacting some folks that I hope can help me change that...,or I'll create a new one!

My name is Russell Nile.

The reason I chimed in is because I initiated this thread a while ago and when I received a recent notification I chimed in,  If it deserves to be a separate thread because of the difference in the vehicles then someone in the Citroen space will have to initiate that.  I assumed it came here because of a similar problem, but I am not familiar with the D-Jet used on the other vehicles.

Thanks for your help!

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
Mehr
29 Mai 2024 18:55 #21535 von Dr-DJet
Dr-DJet antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Hi Russell,

thanks for sharing your firstname. I was not aware that it had been your thread before. All I want to hint is that it makes sense to discuss both cars separately.
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)

Dieses Bild ist für Gäste verborgen.
Bitte anmelden oder registrieren um das Bild zu sehen.

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

Mehr
29 Mai 2024 19:30 #21538 von Samuel
Samuel antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Actually, since I am the one who posted in response to Russell's post (because it was the same issue be it on another car).

In my mind, it makes sense to group similar problems together, since it is all D jetronic related. But happy to start a new thread if the group feels it is better.

Many thanks
Samuel

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
Mehr
29 Mai 2024 21:46 #21539 von Dr-DJet
Dr-DJet antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Hi Samuel,

if you and Russell are happy with it, then I am happy too. I was just afraid to mix two quite different cars.
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)

Dieses Bild ist für Gäste verborgen.
Bitte anmelden oder registrieren um das Bild zu sehen.

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

  • RussellWithABenz
  • Autor
  • Offline
  • Frischling
  • Frischling
Mehr
29 Mai 2024 22:47 #21541 von RussellWithABenz
RussellWithABenz antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
It's all good from my perspective. As long as it is helpful. It's not wrong to have it's own thread with a reference to this too.

Not sure there is a "right" or a "wrong" here.

Thanks again for your input!!

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

Mehr
30 Mai 2024 05:54 #21542 von Samuel
Samuel antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Thanks Dr-DJet

Could you tell me how to measure the volume out of the fuel pump?

Also, as I had mentioned before, with the ignition on only (engine not running) I am getting 22 PSI (about 1.6 bar), but 30 PSI (about 2 bar with engine running).

Should the pressure be about 29.5/30 PSI (~ 2 bar) with ignition only on?

Another experiment today... I plugged the intake air temp wire back in... idle if rough and there is hesitation during acceleration. But if I disconnect the the full-load hose from the full-load switch, idle improves, and there is no hesitation upon acceleration, even with the air temp sensor plugged in.

Since both situations lead to enriching the fuel, I think this conforms my car is running too lean. Now onto more through vacuum leak detection and ???

Many thanks for the valuable information

Samuel

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
Mehr
30 Mai 2024 10:02 #21544 von Dr-DJet
Dr-DJet antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Hi Samuel,

your fuel pump 0 580 463 005 must bring at least 355 cm³ in 30 seconds.measured at return line to tank after pressure regulator. After ignition ON your pump will run for 1 to 2 sec. Pressure may drop to 1,6 bar after it stops.

How I would continue on a DS 23 inj:
  • Verify that injectors spray properly and same amount
  • Measure resistance of injectors from ECU to GND
  • Verify that cold start valve does not inject
  • Check manifold for vacuum leaks
  • Check pressure switch for full-load for leakage and proper operation
  • Verify that no one fiddled with MAP sensor potting
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)

Dieses Bild ist für Gäste verborgen.
Bitte anmelden oder registrieren um das Bild zu sehen.

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

Mehr
30 Mai 2024 18:34 #21547 von Samuel
Samuel antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
Thank you Dr-DJet

I have done some of these things, but will continue with the check list you proposed.

Will update as I move along with testing.

Best
Samuel

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

Mehr
29 Juni 2024 10:49 - 29 Juni 2024 10:54 #21691 von Pcircle
Pcircle antwortete auf Slight mis-fire at partial throttle...until I disconnect air temperature sensor
.
Letzte Änderung: 29 Juni 2024 10:54 von Pcircle.

Bitte Anmelden oder Registrieren um der Konversation beizutreten.

Ladezeit der Seite: 0.185 Sekunden
Powered by Kunena Forum
Forum Latest
Letzte Auto Artikel

Dr-KJet - 26 Dezember 2023

Mit der Einführung des ABS im Mercedes-Benz W116 musste eine Lösung her, um sensible...

Super User - 28 August 2022

Wir wussten ja dank Norbert und Immanuel schon, wie es ist, ein Gebiss für den Citroen SM...

Dr-Djet - 19 Juni 2021

Bei der Restauration meines in 12/1968 gebauten W111 280 SE/C Cabriolets wollte ich auch alle...

Dr-DJet - 24 November 2020

Wie wir auf jedem Workshop zeigen, ist für die Einstellung und Beurteilung eines Motors ein...

Dr-DJet - 07 August 2020

Nach 50 Jahren sind die alten Zündverteiler der Familie JFUR 6 oftmals schwergängig oder fest und...