Urq MB

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <0025663D.00401962.00@smtpmta.mandg.co.uk> Daryl_Roxburgh@mandg.co.uk writes:

> Would anyone like to comment on the following statements made by my garage
> regarding my MB Urq:

Boy, have you found a garage that knows _NOTHING_ about MBs!

Comments in response are taken from:

     "Reparaturleitfaden Audi quattro - 2,14-u. 2,22 l Einspritzmotor
      (K-Jetronic, Abgasturbolader) Ausgabe 10/87   D 000.5147.00.00"

I only have it in German, I'm afraid.  But it IS the original factory
document.

> 1    MB purely mechanical control of boost, no electrical control

Frame 21.8     Describes how to test maximum turbo boost pressure.

Frame 21:9    "Werden die Sollwerte nicht erreicht, Ansteuerung des
               Magnetventils fuer Ladedruckbegrenzung (...) pruefen."

Frame 28:107:  The test for the "Magnetventil fuer
               Ladedruckbegrenzung" - "Magnetic valve for turbo boost
               limiting."  Frame 28:108 shows how to test continuity
               to the ECU.  Pin 19 of the ECU drives the grey/yellow
               wire on the valve.

So the _FIRST_ thing you do if boost is unsatisfactory is test an
_electrical_ part that's controlled by the ECU.  Looks like ECU boost
control to me.

You will further notice (Frames 21-3 and 21.9) that the WR engine's
boost test has to be corrected for ambient temperature whereas the
MB's does not.  The reason is that the MB's boost is electronically
controlled - a specific range of values is given rather than a graph.

> 2    WR & MB turbo's are the same size, only the cooling is different

That has to come from someone who's never held one in each hand.

> 3    WOT switch has no effect on boost

This is a troll, right?  Nobody is THAT stupid!

> 4    There is no overboost on an MB, only on a 20V

Frame 21.9:   "Hinweise:  Es tritt fuer ca. 1 - 2 Sekunden
               eine Spitze beim Messen des Ladedrucks auf,
               die jedoch nicht gemessen werden darf."

That "Spitze" (look it up) is the overboost.

> 5    Diff locks are never used so don't expect then to work therefore not a
>      warrenty item

Same could apply to the ABS ...

> 6    WOT switch just needs cleaning not replacing, no its not a sealed unit

It takes me a couple of hours to open one up.  At GBP30 an hour, GBP38
for a new one is a snitch.

> BTW has anyone else seen a Hitachi ECU with what looks like a German
> factory fitted chip with a paper label with writing on, and
> spreading of the laquer where the chip has been removed/inserted?
> Interesting point is the fact that it looks like factory fitting,
> not an aftermarket from the history.

No.  I've looked inside a dozen or so, and only ever found an aluminised
foil sticker saying "MAC12D" in dox matrix letters, printed on the label
in portrait orientation.

--
 Phil Payne
 Phone: 0385 302803   Fax: 01536 723021
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