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

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17 Dez. 2019 11:38 #12846 von 21571
D Jetronic low to mid throttle surge wurde erstellt von 21571
Hi, I have a 1974 Alpine A310 in Australia with d Jetronic injection.
It has started a low to mid throttle surge. It's ok at full throttle but uses lots of fuel.
I changed MAP sensors to a spare i was given. It runs better but not perfectly. I checked the original MAP and it holds pressure and readings with the multimeter seem fine.
Can anyone suggest where I start looking for the issue?
We don't have many old fuel injection specialists left here!
Thanks Tim.

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17 Dez. 2019 13:07 - 17 Dez. 2019 13:10 #12847 von Dr-DJet
Dr-DJet antwortete auf D Jetronic low to mid throttle surge
Hi Tim,

low to mid throttle surge sounds like broken MAP sensor. If both show different results, I would be supicious. Also leaking cold start valve could be an issue and of course fuel pressure and engine temp sensor. We once discussesd a case here where someone in Australia had drilled into a Citroen MAP sensor and then repotted it like that.
Viele Schraubergrüße - best regards, Dr-DJet Volker
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Letzte Änderung: 17 Dez. 2019 13:10 von Dr-DJet.

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17 Dez. 2019 14:15 #12848 von nordfisch
nordfisch antwortete auf D Jetronic low to mid throttle surge
Hi Tim,
did you check the Bosch part # of the other MPS?

It has to be the 0 280 100 055 - no alternatives.

Vacuum leaks (maybe the hose towards the MPS, maybe other leaks) would cause a rich mixture, too.

Regards
Norbert
Folgende Benutzer bedankten sich: 21571

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18 Dez. 2019 05:00 #12849 von 21571
21571 antwortete auf D Jetronic low to mid throttle surge
Thanks guys.

The MAP that came off probably was on an R17 Gordini originally. My car had been converted to carbs, but was rebuilt back to factory in '92 when it came to Australia from New Caledonia.
The one I have on was from an A310-4 that was converted to a modern computer and multi-throttlebodies.
The original has 0280100048 stamped into it, not sure what's on the one now fitted.

I'll work through the sources of vacuum leaks, then fuel pressure. I have a spare original regulator too.

A modern computer and sensors are on the wish list. Been told $A5500 plus labour and dyno time. That's come with the 1800cc upgrade.

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18 Dez. 2019 05:03 #12850 von 21571
21571 antwortete auf D Jetronic low to mid throttle surge
My engine

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18 Dez. 2019 11:17 - 18 Dez. 2019 11:17 #12853 von Dr-DJet
Dr-DJet antwortete auf D Jetronic low to mid throttle surge
Hi Tim,

a 0 280 100 048 MAP sensor? That is a type 1 from Citroen. You should have a 0 280 100 031 or 055 as you can see from chapter 4 of my compendium

Please start in verifying component nos of all your components:

  • ECU
  • MAP sensor
  • injectors
  • throttle switch
  • fuel pump
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107

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Letzte Änderung: 18 Dez. 2019 11:17 von Dr-DJet.

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18 Dez. 2019 22:18 #12858 von 21571
21571 antwortete auf D Jetronic low to mid throttle surge
Hi Volker,

It's been running that MAP sensor for the last 25 years without an issue until recently.
I'm not sure if R17Gs were Australian assembled, R12s were. Maybe that's why the sensor is different.
I assume that the mechanic used an entire R17G system when re-fitting to the car. That was in '92 and he's forgotten a lot of those details in that time.
I'll check the currently installed MAP soon, and the other part numbers.
We only have one other D-Jet A310-4 in Australia, I'll ask the owner to check his MAP.

Cheers

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18 Dez. 2019 23:43 #12859 von Dr-DJet
Dr-DJet antwortete auf D Jetronic low to mid throttle surge

21571 schrieb: Hi Volker,

It's been running that MAP sensor for the last 25 years without an issue until recently.
I
Cheers


Hi Tim,

I've heard such statements numerous times. And I could not disagree more. A 048 is a type 1 MAP sensor without full-load diaphragm. Your car needs the correct type 2 diaphragm MAP sensor plus the other components.
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107

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19 Dez. 2019 07:13 #12860 von 21571
21571 antwortete auf D Jetronic low to mid throttle surge
I'll take the fitted MAP off tonight and check the number.
This is my ECU and injector.

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19 Dez. 2019 10:27 #12861 von Dr-DJet
Dr-DJet antwortete auf D Jetronic low to mid throttle surge
Hi Tim,

green injectors (035) and ECU 0 280 000 025 seem okay. Throttle switch no. is stamped on its back. So it will only be readable when you remove it.
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107

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19 Dez. 2019 10:36 #12862 von 21571
21571 antwortete auf D Jetronic low to mid throttle surge
Hi Volker,

Thanks for your help.

I'll attempt to pull the throttle switch and other MAP tomorrow.
I've asked the owner of the only other injected A310-4 to check the numbers on his MAP and ECU. He bought that car in France in 1978 and it's completely original

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19 Dez. 2019 11:17 #12863 von 21571
21571 antwortete auf D Jetronic low to mid throttle surge
Hi Volker,

The switch cannot be removed without taking the throttle body off the intake manifold, hopefully enough of the number is visible in the attached picture. The fitted MAP is shown also. I believe this to be an original. I have another ECU with the same part number.
MAP number lines up to what you expect.
Perhaps the old one has failed and the ECU etc needs tuning to this one? It has not been used in 20 years.
I have read on your excellent site that fuel pressure is important. I'll borrow a friend's pressure gauge and check. I have another fuel regulator also.

Thanks, Tim.

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19 Dez. 2019 14:18 #12864 von Dr-DJet
Dr-DJet antwortete auf D Jetronic low to mid throttle surge
Hi Tim,

throttle switch 0 280 120 018 is also correct. Normally correct ECU and MAP sensor can be combined without problems. They were not tuned to each other. Of course tolerances of both can negatively add up. But if your MAP sensor is with rivets, has a date of manufacture from 70s (3 digit no on rivet upper right) and keeps vacuum, I would not be too suspicious about it. On the other hand there must be a reason why it was swapped.

But try fuel pressure first.
Viele Schraubergrüße - best regards, Dr-DJet Volker
Alles für den Mercedes-Benz R/C 107 und W116 in der SLpedia Sternzeit 107

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19 Dez. 2019 16:42 #12865 von nordfisch
nordfisch antwortete auf D Jetronic low to mid throttle surge

Volker schrieb: ...

But try fuel pressure first.


... and check the vacuum line towards the MPS.
A clogged or broken line would lead the MPS to transmit 'full throttle' signal towards the ECU in every condition except idle.

Regards
Norbert

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10 Jan. 2020 11:36 #12923 von 21571
21571 antwortete auf D Jetronic low to mid throttle surge
Hi Norbert, haven't had a chance to do any work on the engine but I have sourced another spare computer and MAP from an R17 Gordini.
I'm waiting on some brake parts to come back, I'm replacing the Renault 16 brakes with vented brakes from a '95 Renault Clio. Should be driving again next week hopefully.

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10 Jan. 2020 19:38 #12925 von nordfisch
nordfisch antwortete auf D Jetronic low to mid throttle surge
Hi Tim,
nice to hear from you again.

The ECU from the R17 Gordini is the same as your original one.

But the MAP isn't a perfect fit.
The R17 MAP is a 0 280 100 031

You need a 0 280 100 055 as I wrote before.


Regards
Norbert

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10 Jan. 2020 20:17 #12926 von 21571
21571 antwortete auf D Jetronic low to mid throttle surge
Hi Norbert, I haven't picked up all the parts yet so not sure about the number, I expect you'll be correct! It's part of a package of parts from a guy who converted to a modern computer. Spare fuel rail, and cleaned injectors too.

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18 Jan. 2020 11:29 #12953 von 21571
21571 antwortete auf D Jetronic low to mid throttle surge
Hi, I've got my hands on a pressure tester. The car was sitting at 1.6bar, now at 2.05. Running much better.
I've got the 055 MAP sensor fitted, I might be imagining it but the car revs out better?
I'll check all the other sensors too.
Thanks for your help, I'm sure I'll be back!

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18 Feb. 2020 09:45 #13188 von 21571
21571 antwortete auf D Jetronic low to mid throttle surge
Hi, I've got a spare set of injectors and a throttle switch too now.
I chatted a lot to some guys very familiar with D-Jetronic over the weekend. We think that possibly my distributor shaft may be worn so the points gap changes.
I've ordered a dwell meter and am borrowing a wideband CO sensor to check my exhaust.
We had Renault Car Club show on the weekend, lots of lovely old Renaults and Alpines. My car the only D-Jetronic one there.
www.facebook.com/RenaultCarClubOfVictoria/

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18 Feb. 2020 10:33 #13190 von Dr-DJet
Dr-DJet antwortete auf D Jetronic low to mid throttle surge
Hi Tim,

I must admit that I never saw an D-Jetronic Alpine yet. Would be levely to have one in my workshops.

A worn distributor shaft would rather effect your ignition than D-Jetronic. Dwell is essential for charging ignition coil. But in D-Jetronic trigger contacts only give a signal for firing injectors. Their opening time is independently determined by ECU.
Viele Schraubergrüße - best regards, Dr-DJet Volker
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