Subject: Trip computer problem

[C1J1Miller@aol.com]

Rasanen Sami.A wrote:
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Hi !
I have a problem with the trip computer (1991 200TQ 20V).
It can not show the fuel consumption or the MPG at all.
It only shows 2000km, when the tank is full and flashes L,
when the tank is almost empty.  After reset, it shows
the average speed almost right. It also shows the
boost pressure correct. I've checked the wirings from
ECU to trip computer (one wire for fuel consumption(pin 32)
and another for engine speed(pin 6) ). I have also
replaced the trip computer circuit board. Please,
help me with my problem.
Regards
S.R s nen
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Hi,
I've copied this message to the '91 200q 20v sublist, as they may be able to
offer further assistance...
My understanding of the computer is that it averages the instantaneous fuel
consumption data from the ECU over a set period of time; thus if you've been
driving sedately on the highway, your "km to empty" reading will increase.
Thus, although you've checked the speed and consumption wiring, I'd think that
your fault lies there or the trip computer is faulty (but you've replaced
that).  Before giving up on it, make sure that the connections and grounds to
the computer and at the ECU are proper; I use a contact cleaner/enhancer
called DeOxit by Caig laboratories.  You may want to try remelting the
soldered connections and grounds at the trip computer to make sure you do not
have a cold solder joint causing problems.  It seems like your computer is
reading 55 or 60 miles per gallon... far from accurate.  Are you sure that the
replacement trip computer is from the same model?

I have a saved post by Phil Rose on adjusting the average fuel consumption;
maximum adjustment is about 15%, and this is likely not your problem.  You can
correct the computed "average miles per kilometer" (in increments of 5%) by
merely changing the setting of one or more of the microswitches located on the
top edge of the instrument cluster (above the board computer).  The factory
setting is for all three switches to be "off" (away from the instrument panel
face).  On the USA computers, it shows average miles per gallon, average
speed, time driven, distance in miles to empty, boost pressure, and gallons
used since startup.  When the fuel gets low, it will flash "30" miles until
reserve, then "25", then "E" (on reserve).  After this, the autocheck will
show the Low Fuel warning.

HTH, chris miller, windham nh, c1j1miller@aol.com
'91 200q 20v ==> http://members.aol.com/c1j1miller/index.html