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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.

Fuel Pressure, Lean mixture, pinging in Volvo 144 B20E

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30 Jun 2025 20:29 #23521 by nordfisch
Hi Chris,
are you sure you used the correct marks for the adjustment?
There are marks from -30° to +30°... and the distributor-cam turns counter-clockwise.

I think, I by myself could have been errated by this, because I almost ever worked on cars with the distributor-cam turning clockwise.

Regards
Norbert

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26 Jun 2026 17:51 #24975 by Nailhead
Dear Volker, I have still not solved the problem completely. I have worked intensely on it from time to time. Based on your suspicion about the pump not delivering what it should I have traced and cleaned all contacts through all wiring to the fuel pump and the relay. That did something good and the pump sounds like it gets enough power. It delivers a bit over 1000 cc in 30 sec, and thus fulfils the spec. However - and here comes the real question; I discovered the charging relay on the Motorola SEV generator was burned of and it delivered almost 16 volts on the battery (15,7V in idle and 15,9 in revolutions) can that in anyway have damaged the ECU or sensors governing the mixture in your experience?
Thank you for your time and effort :)

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26 Jun 2026 19:24 - 26 Jun 2026 19:25 #24976 by Nailhead
I am however doubtfull if I have a false air leak some where I cannot detect - I have tightened all malifold bolts - again - and checked the AAV function again. But still - when I set the throttle clap as per std settings I have to close the idle pinbolt completely before it drops in revolutions to a proper level. It also boggs quite a bit in the first few degrees of throttle movement, until it picks up speed. Anybodu have a good idea about where I shall look for false air?  
Last edit: 26 Jun 2026 19:25 by Nailhead.

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03 Jul 2026 17:17 #25022 by Nailhead
Hi Norbert, I think I have the correct marks on the pulley, I have because this pinging problem is a utter and complete mystery to me checked that the zero mark is when the #1 piston is in top and that checks out. 

Today I stumbled over a nice instruction about ignition timing and I almost yelled heureka. Swiftly I created the SVO2902 (see picture) out of a sewage plug and some small bits, so now I could force the revolutions down to 800 without fiddling with throttle adjustment.
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I removed the vacuum line on the manifold, adjusted the revs to 700 dialed the distributor to the mark 10BTDC - and readjusted the idle screw to the new timing. The pinging went ballistic - it knocks hard on the least throttle under load now. 

I have no idea if the springs in the distributor is so weak they just advance it to plus 30 when the vacuum retard release its grip as the throttle is opened up.
Is it possible to acqiure new springs for the JFURX4 distributor any where? I have looked but I cannot find anything? I have btw tried two JFURX4 distributors with very little change in pinging.

Moreover the engine runs rough in idle - and the potentiometer on the ECU box have to be almost all the way clock wise to make it as stable as possible.
Throttle and the throttle stop has been adjusted as pr recommendations. AVV closes the T slid. Pump deliver 1.1L/30sec at 2.2 Bar pressure.

Any suggestions on where I should look now?


 

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03 Jul 2026 23:30 #25026 by nordfisch
Hi Chris,
some springs are offered here:  roland-merz-katalog.de/en/distributor

Regards
Norbert
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