[s-cars] Charlie Springs??

[Brett Dikeman]

At 8:12 AM -0700 1/13/02, mlp wrote:
>Frank & Charlie et al. -
>
>Thanks.  Shortly after making the post and after an early morning cup of
>Costa Rican coffee to chemically inspire my limited number of brain cells to
>attempt a warm reboot (I'm advised that cold reboots are a bitch), on little
>further reflection it came to me that I should have one (or something like
>one courtesy of a previous owner's excursion in to the world of TAP.)  A
>search of the garage & voila, not one but what looks to be two variants of
>the miscreant.

Whoa...hold on a sec here, mental bell just went off.  Do you have a
TAP ecu in the car?  TAP offered their ECU for 20vt's in two
packages.  One with, one without, a spring; I don't think the spring
was sold separately, could be wrong.

What are the symptoms?  I had a TAP ecu for my 200q20v, no spring,
for 2-3 years and it was causing all sorts of boost problems, which I
could -never- track down; there was a strange hesitation/3-spike
surge in boost at highway speeds that seemed to go away after an hour
or two of driving; there were problems getting full boost, too.  The
code is very badly designed and requires the spring to appear to work
properly(no other tuner's ECU requires the spring.)  As soon as I
swapped over to Ned's III+, there was far more power and none of the
previously mentioned problems.  Goodbye, TAP!

   If you're unsure as to whether the ECU is stock or chipped, turn on
the ignition and check the boost gauge(if your model S6 has it, I
never remember which S4/6's do/don't, sorry) and if it reads .8 bar,
tada, its a chipped ECU(well, this trick works on the 200q20v.)  If
you don't have the boost gauge, my next suggestion is to ask if
there's another S6 owner with a stock ECU who will swing by for 30
min and swap ECUs with you(a modified ECU might be risky if the
problem is not a TAP ecu or such; I would suggest trying a stock ECU
first.)

If it is a TAP ecu and problems go away with a stock ecu, see if
someone has a IA/Hoppen/MTM chipped ECU and will swap for a half hour
with you.  If no problems, send the ECU to Hoppen or Ned; ask if
they'll discount their price, since there is no pressure transducer
swap necessary, you've already got one in there, they just need to
put in their roms.

>I have my personal doubts that the fat spring will provide any sort of
>solution to the present problem, but its been strongly "suggested" it be
>tried in a quest to eliminate possible cause or causes for the continuing
>present low, to very little boost quandary.

It quite possibly will solve the symptoms, but not by properly fixing
the actual problem.  If the ECU is getting fooled by a bad sensor, or
you're running a bad tap ECU, it's far more important that you
address those problems.

If it's not a TAP ecu, have you dumped the codes from the ECU?  Have
you checked that there is no overheat signal from the multifunction
temp sensor?  Does the wastegate frequency valve's resistance check
out to spec as per the Bentley?(these are known to go; mine was toast
when I bought the car at 100k miles.)  Either can cause the
mysterious 1.3-1.4 bar maximum.  Obviously if there were surging I
would suggest an intake system leak, and I assume the air filter is
in good shape(it would have to be really clogged, anyway.)

BTW, at least some of the S-cars have far better ECU diagnostics than
the 200q20v, at least on Kirby's S6(95.5 model, I believe?)  With a
scantool, you can pretty much check out any value the ECU is reading.
I saw a generic scantool with a VW adapter reading out, but I think
VAG-COM is now advanced enough that you should get the same stuff.
For $200, its a great deal, and he's even got data logging now,
perfect for boost silliness.  I highly suggest it, especially for
later car owners who have ECUs that will offer up more information.

HTH,

B
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