[s-cars] what's this wire for?? (Motronic)

Steve Eiche seiche at shadetreesoftware.com
Thu Jul 29 17:25:15 EDT 2004

I am sure that Feico will jump all over this one, but that is definitely NOT any VMAP wiring.  As you can see, that ECU has a Bosch pressure sensor.    The wire seems to go from pin 18 to the transient voltage suppressor.  There should already be a trace on the board to do that.  My guess is that the transient suppressor had been blown in that ECU and someone put a BIG fuse in the circuit, burning the trace off of the board.  Then the blown component was replaced and the wire was added in place of the trace.  That's not the preferred way to fix that trace, but it should work fine.  

Looks like someone without a lot of soldering experience played with that ECU...


Marc wrote:

"While I had my ECU apart for socketing, I found a wire that had been
hacked onto the board from one of the diodes (I think) directly to one
of the pins on the ECU connector:


Any speculation as to why this is there?  I got this ECU as an exchange
for mine which died on the operating table during Mihneathon last
weekend.  Some kind of boost mod/hack?

In general the board looked pretty ugly in a lot of places.. you can see
some of the other pics by browsing around that album.


My guess that this is a mod done by the people at www.moreboost.com. It is especially probable if this ECU has their VMAP-D pressure transducer.

This jumper allows you to use the full throttle switch (or some throttle switch) to program the VMAP remotely. Handy if you are out in the middle of no where, it is 110 degrees, and Billy Bob's gas station only sells 85 octane. Or if you are racing on a hot day. Apparently, by dialing back the transducer from 3.0 bar to 2.7 down to a limit of 2.5, or so, boost is reduced.

Or something like that.

Craig Lebakken
94 S4
Boost still limited by the duct tape on Mr. Michelin.

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