2.1 DJ dls unit - the white plastic thing 251 906 083 A

[silverbullet]

The DLS only affects the trigger/coil timing, not any individual cylinder, so any means to achieve the spark arriving "early" will work.
If for instance the dissy Hall trigger has an output pulse interval time of say 0.1 seconds, if the DLS can delay this by 0.09 sec then the next pulse will be, in effect, advanced by 0.01sec.
Its not dependant on any particular cylinder, just that the next spark arrives (relatively) early.
This might be based on a false premise of course!
This is all getting a bit too close to typical samba style conjecture and "in theory" guesswork for my liking.

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[937carrera]

The DLS only affects the trigger/coil timing, not any individual cylinder, so any means to achieve the spark arriving "early" will work.
If for instance the dissy Hall trigger has an output pulse interval time of say 0.1 seconds, if the DLS can delay this by 0.09 sec then the next pulse will be, in effect, advanced by 0.01sec.
Its not dependant on any particular cylinder, just that the next spark arrives (relatively) early.
This might be based on a false premise of course!
This is all getting a bit too close to typical samba style conjecture and "in theory" guesswork for my liking.

I believe we are on the same page theoretical page.

At 940 rpm each hall sender pulse would normally be every 0.032 seconds, and 1 degree of advance would be 0.00018 seconds, if my maths is right at this early hour. As the abbreviation, (so I understand) stands for Digital Idle Stabilisation, the box of tricks must convert the analogue hall signal to a digital signal, to which a time offset is applied - for the next spark.

I feel a bit bad for Aidan. He puts a wanted ad up and it turns into a quite technical thread. It would be great if the technical bit could be split off into the technical area, leaving his original ad awaiting a response.

[Mr Bean]

Yes that did occur to me too but then who am I to talk about tidyness . There'll be ructions if Mrs Bean Spots it though

[silverbullet]

I might just have one in the box of efi looms, but its upstairs in the stores at work and I dont go up there past noon if I can help it when the weather is hot!

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[silverbullet]

I concur
960rpm = 16 crankshaft rev/second. Dissy runs at half this speed so 8 rev/sec, or 32 triggers per sec on a 4 cyl
32Hz or one pulse every 0.031 second?

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[itchyfeet]

I feel a bit bad for Aidan. He puts a wanted ad up and it turns into a quite technical thread. It would be great if the technical bit could be split off into the technical area, leaving his original ad awaiting a response.

I have taken a copy of all comments, if mods want to delete the chat I will post the copy

[tobydog]

I feel a bit bad for Aidan. He puts a wanted ad up and it turns into a quite technical thread. It would be great if the technical bit could be split off into the technical area, leaving his original ad awaiting a response.

To quote Aidan - "we are just trying to figure exactly what it does and how"

A piece of light reading:-
https://patents.google.com/patent/US4318387" onclick="window.open(this.href);return false;

It references one of the chips possibly used, MC14538BCP.

From reading the disclosure of invention, the unit counts pulses, when the frequency goes below a certain value it initiates a timer which creates a pulse from a fractional frequency of the first. The pulse is then advanced to fire the next cylinder.

?????

[silverbullet]

I would say that this tallies quite well with the logical conjecture/guesswork so far?

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[Mocki]

I feel a bit bad for Aidan. He puts a wanted ad up and it turns into a quite technical thread. It would be great if the technical bit could be split off into the technical area, leaving his original ad awaiting a response.

I have taken a copy of all comments, if mods want to delete the chat I will post the copy

Post split , original wanted add is just the wanted advert , the chat is here , in technical so it won’t self delete 28 days after the last reply

[937carrera]

Thanks Steve

[937carrera]

So, from the wanted ad, Aidan now has one to play with - whoever "the Prof" is

I'm looking forward to learning more....

[937carrera]

Just wondering if you ever had a chance to look at this yet Aidan ?

[Aidan]

swapped out on Neil's van with no appreciable difference (in summer) from the Passat version which he had fitted, the differences between the golf, passat and T3 ones are obviously pretty small, they all do the same thing, there's minor variations in the idle optimum spec that's all but as they are all basically the same ignition system the processes are the same, probably even the firing order doesn't actually matter as long as there are the same number of cylinders (hence the wbx6 has it built into the ecu like the digifant - it's a hybrid) and the stuff that you guys found online and elsewhere and referenced above explains it pretty well - I was struggling to understand how the spark could be advanced until it was explained that it is intercepted/anticipated = advanced, it's a digital enhancement on a simple mechanical system to provided a smoother idle; with the next evolution, Digifant, they just eliminated the mechanical advance and made the timing fully digital
lots of DJs run without DlS with the plugs joined together and they usually have to be set up to idle a little bit quicker so they will idle when really cold, and they then seem to idle a bit quick when hot, as the idle air bypass valve and control unit can't operate quick enough or sensitively enough on their own to keep it as smooth and so the set up is a bit more compromised; as it it only affects idle it doesn't massively change fuel economy and above idle performance is not affected
when air bypass valve isn't working optimally and DlS is bypassed then idle will be difficult to achieve, a lot of the time air bypass valve is stuck or only moving over a restricted range and cleaning it can be all that is needed to resolve issue
not all air bypass valves noticeably vibrate when ignition on and engine not running in my experience so if it appears to work but doesn't obviously vibrate don't replace it