(08-29-2017, 12:53 AM)firen456 Yes, me... 8mm pump, 716 gearbox with SMF, HE351

(08-29-2017, 01:45 AM)firen456 Yes, minimized it by adding a additional spring to the rack. Only have jerking in part-load condition. The coil has too lees spring tension at low IQs. Also using the new pump map helped to get rid of the jerking issue. There are still some oscillations left. First I will try to add a harder spring. If this will work I will set the brackets towards more fuel = more tension on same IQ. 
Have you problems with nailing? The 8mil elements nailed horribly in part load. I've got a soluton about this... What about nailing on the 7.5mm elements?

(08-29-2017, 11:54 AM)maxypriest I'm not exactly sure what has done it however I have made a number for changes to my car and the jerk has completely gone after about 1200 rpm.

(08-30-2017, 03:53 AM)maxypriest Well that’s the catch, I’m not using an EDC, it’s a mech pump that had the bonanza/Jerk.

I have not touched the engine/transmission.

I changed the rear flex disc to a bigger one, a stronger prop, longer ratio 210mm diff, poly bushed diff to subframe mounts, uprated trans mount different wheels and tyres. Something I did there eliminated the jerk, (it’s not reduced its eliminated) and the car is now infinitely nicer to drive.

(08-30-2017, 05:04 AM)maxypriest interesting! 4 mech pumps without jerk? Nice.
DPUK is working on something that might help. Very early days.

(08-30-2017, 10:28 AM)barrote Everybody who has low ratio diff s that i know with maxed out mech pumps have some jerk ... DMF 's and other fancy harmonics absorbing devices help... but the thing is i start to belive in witches...
Adding tension to the rack spring and diminushing the tq control control help a lot... but in some pumps does not solve the matter at all.
I have a pretty much idea of why it does in mech pumps but the idea need to be tested and it takes time....
Regards

(08-30-2017, 12:51 PM)barrote Sorry baldur ,
i was not talking about that ... its nothing related to that ... jerking people complain and i too have is part load driving and not cause of what u refer above, wich i do not refute.
Looks like people complain of dsl1 powered pumps too, and why is the driver induced oscilations... well i have no answear to that ...
For the mech pumps i have , and when i have complete control over it i'll post my conclusions , and solutions.
For the moment i can recomend to increase rack spring tension to 2 as much , and for those u can and know how to do it reduce tq control cut out to min.
I do hope toguether we can fight this problem with success.

(08-31-2017, 12:42 AM)NZScott And here I am thinking it was my right foot going back and forth with the car going back and forth...

(09-02-2017, 08:12 AM)firen456 Have you measured your spring? I didn't have time so far to make a picture... I'm very busy this weekend

(09-04-2017, 07:50 AM)firen456 Ok, wonderful   I wonder what causes this issue... Maybe he will find out what's going on there. The EDC-pumps seem to be weird in some cases... Where a 8mil element is running fine in a mech pump, the same element is nailing like hell in a EDC-pump for example. I'm interested if this oscillation-issue can be caused in a pump-bench, too... Whithout the engine running, there is no oscillation, only with the engine running it appears. And only at a certain enginespeed. The same thing about the nailing of the 8mil pump. But there is a solution to minimize it.

(09-09-2017, 11:13 PM)JoeB When you have resolved the issue, please let us know.
I have a spare EDC pump here on my second 606, which I would like to send to Goran for an upgrade, but it's a completely pointless exercise for me to do so if there is no proven solution available.

My other pump is mech603, and reconditioned to new locally but tuned with .964 elements - it is obviously quite good for it's intended function. Stock 606 turbo, so no need to go bezerk on it.

The spare engine I want to go DSL1 for my own reasons. If 7+mm elements cause the oscillation then I'll need some documented facts to support doing it.

(11-02-2017, 04:27 PM)BobbyBreeze Thought this could be useful for this thread. DieselpumpUK anti jerk setup. Could be worthwhile trying on the EDC pumps with larger elements.

https://youtu.be/KucwBFD3nr4

(11-24-2017, 04:01 PM)Petar On old diesel engines that would jerk(rpms go up and down mostly at idle and low rpm) we used 90 weight gear oil instead of regular motor oil in the pump governor. The thick oil would dampen worn out governors and stop the hunting effect. Of course this is impossible in engines that use pumps lubricated from the engine oil circuit.
The DPUK solution is very similar and quite genius.