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Re: T.A.P. Modified ECU


The TAP mod you describe is (I believe) the *EXACT* same "mod" performed by
SuperChips on my '89 200tq.  The diode is a 4.3 volt zener diode and the
resistor is a 470 ohm resistor.  I can even tell you the exact location and
orientation of these two components.  It served to limit the signal from
the pressure transducer to the equivalent of a reading of about 1.25 to 1.3
bar.  This is why the dash boost gauge did not work.  It was reporting what
it read from the transducer output which had been jimmied.  

The SuperChips mod also included an extremely strong replacement spring
which likewise required some significant leverage in order to install.  The
only difference is, apparently, that SuperChips did not even make a charade
"substitution" of the chip.  Similarly, the end cap was also blown off my
intercooler on the first really spirited romp after installing the mods.

What was that about great minds?  :-)

At the time you speak of I was under the impression that the TAP offering
was considered much better and more cautious than the SuperChips mod.  Is
my memory faulty?  I found that this simple mod in my car proved quite
usable once a hose clamp was strapped around the intercooler to reinforce
the end caps and a decent supplemental boost gauge was installed.  The
heavy duty spring was later replaced with a pressure regulator providing a
regulkated amount of boost pressure above the WG diaphragm which had the
effect of increasing the strength of the spring but doing it such that the
"strength" of the spring could be adjusted.

I drove that car another 60K+ miles until I unfortunately totalled it and
then installed the ECU in another '89 200tq since sold to a list member and
still being driven satisfactorily today (I haven't heard different, anyway).

There was much discussion about potential lean fuel mixtures and burnt
valves, etc., at the time.  I did not experience any problems with this in
either car with >60K miles on each that I put on the cars after the mods
were installed.  It most certainly did produce much more power.  Addictive
power.  :-)

At 02:48 PM 09/25/1999 -0400, you wrote:
>Earlier, Mike Mulholland wrote:
>>         you mentioned previously about your disapointment with a tap
>> modified ecu. following your post i noticed that although my car moves
>> really fast... the on board boost guage never goes above 1.4. is this an
>> indicator of a similar mod? i purchased the ecu used from a lister and it
>> has been good so far.
>> 86 5kcdtq, tap chip sjm spring
>Funny you should mention this, at this late date.
>Back about 1994, before I made the first batch of springs, I bought
>a T.A.P. "upgrade" kit for my 86 5kCSTQ.  To make a very very long story
>short, I won't go into all the details - but here's the short version.
>I sent my MAC-10 ECU to them, and it came back with instructions and
>a wastegate spring.  And the original EPROM chip.
>On inspection of the MAC-10, they had desoldered the EPROM chip, and had
>soldered in a socket, that held an EPROM chip with their label on it.
>I installed the new wastegate spring, which was so strong that I had to 
>use a long pry bar against the firewall to get the wastegate cover pushed
>down enough to start the 8mm nuts.  This should have set off warning lights.
>Before very long I blew the end off the intercooler.  I repaired it and
>pulled their spring back out.  Annita told me they had sent the wrong
>spring, and she sent me another one, which worked OK.  Meanwhile, while
>I was waiting for the spring, I read out the contents of the TAP EPROM
>chip and the original EPROM chip on an EPROM burner that was lurking 
>around.  Comparing the contents of the two chips showed that they were
>identical <!>  They had soldered in a socket and changed the EPROM chip
>just so they could claim to have a modified chip when they really
>did not modify the chip.
>Anyway, I also had the problem with the dashboard boost measurement
>never going over 1.3 or 1.4 BAR.  I called them numerous times about
>various problems, including the engine cutting out sometimes.
>Inspection of the ECU showed that they had soldered (I don't remember 
>exactly) a diode and a resister or two onto a couple leads of the pressure 
>transducer on the ECU motherboard.  What this is doing, is limiting the 
>pressure transducer signal that can be seen by the ECU.  This is why you
>only see 1.3 BAR on the dash display.  With 20/20 hindsight, I believe the 
>cutting out was because their "bypass" of the overboost sensing circuit
>was letting the ECU see enough of a pressure signal from time to time
>to cause the ECU to shut things down momentarily.  During all this
>fiasco, the ECU was sent back to them one time for tinkering without
>making any difference.
>Finally, I got them to agree to give another ECU w/o mods since I was
>then convinced they had screwed up the ECU.  since my son lives in 
>Sarasota Florida, I stopped by their one room storefront which was just
>north of Tampa.  A long haired fellow named Trevor Gurian was there,
>and refused to give me another ECU, in fact he denied that they had ever
>said that they would give me an exchange.  He said that they would remove
>their mods from this ECU.  Finally, I had him do that.  They refused to
>provide any money refund even though I gave them back their wastegate
>springs.  Looking at the ECU later, I saw they even removed the EPROM 
>socket and resoldered the original EPROM onto the board.  While they
>were doing this, however, they screwed up some of the printed circuit
>traces on the back of the motherboard and then repaired them by soldering
>jumper wires on the back of the motherboard.
>All of this got posted to the quattro list several years ago when it 
>happened.  As far as I am concerned, they are right on the edge of
>fraud.  I was suprised to see their adv on some of Dan's quattro web
>pages the other day.  I don't think promoting their business is in the 
>best interests of Quattro owners.
>One result of being burned by TAP, was my subsequent efforts to make
>wastegate springs and then to make the springs available at cost.
>    - Charlie
>Charlie Smith   charlie@elektro.cmhnet.org  614-471-1418  
> http://elektro.cmhnet.org/~charlie/  Columbus Ohio   USA
> 4 wheeled fleet:	                     2 wheeled fleet:
>_________________________                  _________________________
>93 V8 Quattro     4,200cc                  95 BMW K1100-LT   1,100cc
>98 Dodge Ram                               95 BMW R100-RT    1,000cc
>    w/ Cummins Turbo Diesel 17PSI          62 BMW R27          250cc
>69 Porsche 911S   3,200cc                  48 Harley FL          74"
> Advertisement:  Very nice, very fast Porsche for sale -
>    http://elektro.cmhnet.org/~charlie/photos/cars/porsche.html
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