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 low to mid throttle surge

  • 21571
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
18 Feb 2020 10:43 #13191 by 21571
Replied by 21571 on topic D Jetronic low to mid throttle surge
Hi Volker, after discussing the cars symptoms we concluded I may have more than one issue.
I had an Alfa Sprint 20 years ago, it had a worn shaft and some of the same issues. Would be fine under load, but not run well when not under throttle. I'd forgotten about it.
I still have a fuel issue, the car is running rich, but did not use an unacceptable amount of fuel in the 250km I did over the weekend.

Please Log in or Create an account to join the conversation.

  • 21571
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
22 Feb 2020 05:18 #13258 by 21571
Replied by 21571 on topic D Jetronic low to mid throttle surge
I adjusted the throttle switch, car much better idle, still a miss though. Fitted a computer I got last week. It's potentiometer was sitting in the middle, mine was hard to the left so could not be leaned out anymore.
Car running almost perfectly. I'm borrowing a wideband this week so will check the exhaust and make sure not too lean, can't afford melted pistons!

Please Log in or Create an account to join the conversation.

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
More
22 Feb 2020 10:24 #13259 by Dr-DJet
Replied by Dr-DJet on topic D Jetronic low to mid throttle surge
Hi,

you do not need a wideband lambda tester. A 4 gas exhaust tester with CO and HC measurement is enough to adjust rheostat on ECU.
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107

This image is hidden for guests.
Please log in or register to see it.

Please Log in or Create an account to join the conversation.

  • 21571
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
22 Feb 2020 11:07 #13260 by 21571
Replied by 21571 on topic D Jetronic low to mid throttle surge
Hi, it all comes down to what I can borrow from friends!!

Please Log in or Create an account to join the conversation.

More
22 Feb 2020 16:08 #13261 by nordfisch
Replied by nordfisch on topic D Jetronic low to mid throttle surge

21571 wrote: I adjusted the throttle switch, .. mine was hard to the left so could not be leaned out anymore.

Hi Tim, you can re-adjust your throttle switch that will be the early version.

Have a look at this photo:

This image is hidden for guests.
Please log in or register to see it.



As you can see, this switch had to be adjusted to the left, too.
And you can see the reason: The microswitch is bent to the outside because of former misadjustment or just because of the years in which the material was bent...
Just readjust the microswitch-feelers and all will be fine again.
You have to re-adjust the TPS afterwards, of course.

Regards
Norbert

Please Log in or Create an account to join the conversation.

  • 21571
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
23 Feb 2020 00:09 #13262 by 21571
Replied by 21571 on topic D Jetronic low to mid throttle surge
Hi guys,

I meant the rheostat on ECU was all the way too the left with no room for adjustment.

Please Log in or Create an account to join the conversation.

More
23 Feb 2020 00:40 #13263 by nordfisch
Replied by nordfisch on topic D Jetronic low to mid throttle surge
Hi Tim,
sorry - I misunderstood what you wrote.

Many guys out there name the TPS 'potentiometer' <is really one in later Jetronic versions>.

Regards
Norbert

Please Log in or Create an account to join the conversation.

  • 21571
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
19 Mar 2020 07:56 #13439 by 21571
Replied by 21571 on topic D Jetronic low to mid throttle surge
Hi guys, hope you're all keeping safe and well, and isolated in your garage!

I've hooked up a wideband and tried to tune according to the manual I have, which is for a Renault R17. Everything should be the same.
Screw in air screw, adjust idle, unscrew air screw until idle adjusted again. Adjust ECU rheostat. Car still is very rich with the rheostat all the way to the left. Throttle switch also adjusted.
Any thoughts?

Please Log in or Create an account to join the conversation.

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
More
19 Mar 2020 11:18 #13440 by Dr-DJet
Replied by Dr-DJet on topic D Jetronic low to mid throttle surge
Hi,

does the 055 you bought leak vacuum? ANd do you have false air in your intake manifold? Your problem sounds like false air when I read that someone had reduced fuel pressure to 1.6 Bar. I like to test this via a fogging machine. But you could also try to measure the vacuum that the MAP sensor sees in idle-run. On a Mercedes-Benz engine you would expect araound -0,5 Bar.
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107

This image is hidden for guests.
Please log in or register to see it.

Please Log in or Create an account to join the conversation.

  • 21571
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
19 Mar 2020 11:34 #13441 by 21571
Replied by 21571 on topic D Jetronic low to mid throttle surge
Both MAPs held pressure, and static readings were ok.
I would have borrowed the pressure tester from work but we've just been sent home and locked out.
False air is a leak somewhere? I've sprayed connections with brake cleaner with no change in idle.

Please Log in or Create an account to join the conversation.

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
More
19 Mar 2020 15:10 #13442 by Dr-DJet
Replied by Dr-DJet on topic D Jetronic low to mid throttle surge
Hi Tim,

if you are sure about false air and MAP sensor then verify:+

  • cold start valve not injecting
  • both temperature sensors on ECU connector
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107

This image is hidden for guests.
Please log in or register to see it.

Please Log in or Create an account to join the conversation.

  • 21571
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
20 Mar 2020 09:30 #13449 by 21571
Replied by 21571 on topic D Jetronic low to mid throttle surge
Hi Volker, I've swapped in a spare cold start injector, will check tomorrow morning if it makes any difference. Can they fail and continuously inject fuel? This would lead to a rich situation which can't be tuned out. Are they serviceable? I've seen some for sale but at £200!
Thanks Tim

Please Log in or Create an account to join the conversation.

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
More
20 Mar 2020 10:38 #13450 by Dr-DJet
Replied by Dr-DJet on topic D Jetronic low to mid throttle surge
Hi Tim,

yes they can leak and can be cleaned by ASNU serive. Also their electrical control via thermo time switch and sometimes relay could be broken.
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107

This image is hidden for guests.
Please log in or register to see it.

Please Log in or Create an account to join the conversation.

  • 21571
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
01 Apr 2020 13:31 #13538 by 21571
Replied by 21571 on topic D Jetronic low to mid throttle surge
Hi, does the air bleed screw that's adjusted at idle make any difference to the mixture when not at idle?
I've been playing with the wideband and fuel pressure while driving and have found that the car runs best with the pressure under 1.6bar. This is assuming the gauge is correct. Over this it is too rich and hesitates at partial load. At 1.5bar the A/F rarely gets above 13.5 so is still safely rich.
There maybe something else wrong somewhere. I don't have to worry about emissions testing here in Australia.

Please Log in or Create an account to join the conversation.

More
01 Apr 2020 14:00 - 01 Apr 2020 14:07 #13539 by nordfisch
Replied by nordfisch on topic D Jetronic low to mid throttle surge
Hi Tim,
following the calculators reducing the pressure to 1.6 Bar means the engine gets about 10% less fuel.
'Only' 10%, not 20% as one could think.

Did you already check the resistances of the temp sensors?

Check them at the ECU-connector (not directly at the sensors) using an Ohmmeter, here is a link for downloading

regards
Norbert

edit: I never had the chance to verify this plan up to this moment. Try to read the air temp sensor against pin 11, too in the case pin 13 shows endless resistance.
Last edit: 01 Apr 2020 14:07 by nordfisch.

Please Log in or Create an account to join the conversation.

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
More
01 Apr 2020 14:51 #13540 by Dr-DJet
Replied by Dr-DJet on topic D Jetronic low to mid throttle surge
Hi,

the idle.run air-bleed screw is like a foot on pedal. it does not affect mixture. Fuel dimensioning is done by D-Jetronic.

A pin-out of whole connecotr is in appendix B . 10-20% too much would fit a missing air temp sensor.
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107

This image is hidden for guests.
Please log in or register to see it.

Please Log in or Create an account to join the conversation.

  • 21571
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
02 Apr 2020 09:33 #13543 by 21571
Replied by 21571 on topic D Jetronic low to mid throttle surge
Thanks Volker & Norbert. I've checked the couple of sensors I have and they're within tolerance. Will check at the ECU connection next.
What sort of performance difference would you expect with it all working properly compared with what I'm seeing? I have a couple of spare harnesses too, one from an A310, one from an R17G.

Please Log in or Create an account to join the conversation.

  • Dr-DJet
  • Offline
  • Moderator
  • Moderator
  • Dr-DJet repariert und sammelt alles! :-)
More
02 Apr 2020 09:52 #13545 by Dr-DJet
Replied by Dr-DJet on topic D Jetronic low to mid throttle surge
Hi Tim,

a wrong mixture firstly causes bad emissions before it downgrades engine performance. And it causes high fuel consumption.
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107

This image is hidden for guests.
Please log in or register to see it.

Please Log in or Create an account to join the conversation.

  • 21571
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
02 Apr 2020 10:24 #13547 by 21571
Replied by 21571 on topic D Jetronic low to mid throttle surge
Hi guys, checked across contacts in the car, then a spare harness and sensor. In car 361 ohms, 352 on the bench at 18c.

Please Log in or Create an account to join the conversation.

  • 21571
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
02 Apr 2020 10:26 #13548 by 21571
Replied by 21571 on topic D Jetronic low to mid throttle surge
Please excuse my work bench!

Please Log in or Create an account to join the conversation.

Time to create page: 0.170 seconds
Powered by Kunena Forum
Forum Latest
Latest car articles

Dr-DJet - 17 May 2016

Chapter 15 of D-Jetronic article series by Dr-DJet describes specialties of Jaguar's D-Jetronic...

Dr-DJet - 31 March 2015

Chapter 9 of Dr-DJet's article series describes auxiliary air valve (or air slide valve), cold...

Dr-DJet - 06 December 2014

Chapter 14 of article series by Dr-DJet gives you a detailled checklist for ticking off every...

Dr-DJet - 06 December 2014

Appendix B of D-Jetronic article series by Dr-DJet lists pinout of all ECUs of all D-Jetronic...

Dr-DJet - 16 November 2014

Chapter 10 of D-Jetronic article series by Dr-DJet describes replacement of your engine wiring...