chipped" '87 5ktqa

[Robert Myers]

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[ Picked text/plain from multipart/alternative ]
Steve,

If you have seen 1.7 on the stock in-dash gauge then you likely don't have
the zener/resistor mod.  With this mod the gauge output is clamped to a
maximum of about 1.4 bar.  Any boost levels about this simply are not known
about by the ECU.

The only way to tell for sure is to pull the IC and open it up.  Look at
the pressure transducer (PT) mount.  Look for one "pin" to be a resistor
rather than just a straight through wire.  Also look for a small zener
diode soldered between this "resistor pin" and another pin four or five
pins away from the resistor.  If these are present then you have the z/r
mod.  The PT is on a small daughterboard above the main board and has a
hose attached to it.

Now, as far as safe boost levels with this mod, I have heard several
stories of engine melt-down (so to speak).  But these have just been
stories.  I have seen no evidence of "This happened to me" type reports.  I
ran the z/r mod on a 1989 200tq with a MAC-11c ECU.  This car also had the
Timmerman shrapnel-knob.  I adjusted the knob such that the maximum boost
was kept below 19 psig (that is about 2.4 bar on the stock gauge if it were
capable of reading that level -which it isn't).  I ran the car this way for
nearly 60K miles with no hint of boost related troubles (other than a blown
Michelin Man hose and an end popped off the intercooler, of course, both
easily solved problems).  I then sold the car to another list member who
put a lot more miles on it.  He has since sold it to another Audi nut who
is still driving it (according to a report I received within the last
week).  I tend to discount these "reports" of serious damage.  Perhaps I
was just lucky.  Perhaps not.

Yes, there are concerns about the mod.  Probably first among them is
concern over excessively lean mixtures (the ECU doesn't "know about" how
high the boost level actually is and therefore meters out only enough fuel
for what it "thinks" is there resulting in a lean mixture.  Lean = hot as
far as combustion temperatures relate.  This could lead to burnt valves and
pistons, etc..  IME, this appears not to be a problem.  Perhaps I was just
lucky.

Believe me, the difference between 1.4 bar and 2.3 bar in a 10 valve I-5 is
absolutely HUGE!!!  Huge as in, "Holy Moley, Batman!!"  Your passengers may
be looking for a dry towel for their seats after their first experience
with a quick burst.  :-)

The main advantage of the z/r mod is that it is VERY inexpensive.  Less
than $5 for parts plus perhaps an hour or so for doing the ECU
desolder/solder operation.  The main disadvantage is the potential for
possible engine damage.  My experience leads me to discount the damage
reports, however, YMMV.

Oh.  Don't try this on a car with a slushbox.   The tranny won't stand up
to the added power.


At 02:44 PM 11/7/2002 +0000, sneekerz at attbi.com wrote:

>Ben (and others):
>
>I also have a "chipped" 5ktqa. I've always assumed it's
>the resistor/diode upgrade, so keep the adjustable
>wastegate close to stock settings, hoping that keeps my
>schrapnel-potential lower. How does one find out for
>sure? My boost reads higher than the 1.4bar mentioned
>when the schrapnel-knob is cranked higher, I've seen as
>high as 1.7, but never kept it there for fear of
>meltdown. You mention opening up the ecu, would it be
>obvious? I assume a real chip would have the name of the
>company on it, would the resistor/diode be obvious as
>well?
>
>steve
>'86 5ktqa
>'86 4kcsq
>kent, wa
>Message: 10
>From: Ben Swann <bswann at worldnet.att.net>
>Reply-To: "bswann at worldnet.att.net" <bswann at worldnet.att.net>
>To: "'c21john at qwest.net'" <c21john at qwest.net>
>Cc: "'quattro at audifans.com'" <quattro at audifans.com>
>Subject: chipped" '87 5ktqa
>Date: Thu, 7 Nov 2002 03:45:43 -0500
>Organization: Swann Family
>
>John,
>
>Sounds like you have the "resistor" mod being used in conjunction with some
>means of obtaining the boost, like schrapnel knob or heavier wastegate
>spring.  See: http://www.homestead.com/ben_swann/boostin.html for details
>on this.
>
>I have long since downplayed it's use in lieu of the economical QLCC chip,
>which provides a greater margin of safety and is a real chip.
>
>The only real way to be sure is to open the ECU up and see what's inside.
>
>On the note about the purchase, if the car is doing fine, then it's a
>keeper.  I have done a lot with my '87 avant, and the TCO is still under
>$8k in over 4 years including purchase price.
>
>Ben
>
>
>
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Bob
*****
  Robert L. Myers   304-574-2372
  Rt. 4, Box 57,  Fayetteville, WV 25840 USA   WV tag Q SHIP
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