[s-cars] Stiffer Waste Gate Spring with stock ECU

[Charlie Smith]

Earlier, Brent Henry wrote:
>
> I happened across a 1.8bar Waste gate spring.  I would like to
> investigate whether or not it would be worth putting this into my
> stock S4 turbo system.  Although I have not checked it... I believe
> that my '92 S4 has a stock spring.  It also appears to be tightened
> down a little.  The allen bolt on top of the Waste Gate Cap is
> turned in about 7 or 8 turns (not sure where it would have been
> set from the factory).

Don't put it in your S4.  With the engine control system on the 20V
turbo engines, you don't raise the boost by changing the wastegate
spring.  You need different chips in your ECU.

The earlier 10V systems were different, you could get by with a little
more boost via a stronger spring.

The 20V system depends on the ECU backing off the boost when it senses
knocking or for other reasons.  If you jack up the wastegate spring
to raise the boost, the ECU can't lower it when needed and you will
have a case of engine self destruction ASAP.


> I'm looking for some guidelines on installing this spring and how
> to test it and make adjustments.  I understand that with the stock
> K24 and the stock ECU, I can only get a maximum of 16psg... which
> should translate into a reading on my digital boost gauge of
> approximately 2.3bar.
>
> I am concerned about running too lean and burning pistons.
> Is this a real concern?

It can be if you've messed with the wastegate spring tension.



> I live near Toronto therefore no high altitude issues.  I also
> understand that you can't always hear the engine pinging, how
> should I reassure myself that this is not happening?

That's the job of the ECU and the knock sensors.

    - Charlie


  Charlie Smith   charlie at elektro.cmhnet.org  614-471-1418
  http://www.elektro.com/~charlie      Columbus Ohio   USA
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  95 S6 Quattro  -  24 PSI, RS2 6 speed, and other features
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