Re: Trip computer accuracy

[steveb@newkla.kla.com (Steven Buchholz)]

Alan Breitman wrote:
> 
> I was wondering if anyone knew how the trip computer calculated avg.
> mpg and mi to empty.  I have a 89 90Q (with a TAP chip, no comments
> please :^) ) and the trip computers calculation for avg mpg and mi to
> empty is not even close to accurate.  The trip computer will accurately
> calculate avg mph though.  TIA for any insight. 

When I bought the '88 5k I actually managed to get an extra couple $100
from the seller because the trip computer didn't work.  He said that the
dealer had replaced the computer module, but there was still a problem.
I found that the variable resistor that senses the airflow sensor position
was not working properly.  Apparently the parts are either not available
or available only with a new assembly.  I was able to make the thing work
better by cleaning the wiper contact, but it is still not reading accu-
rately.  Depending on the model and year of your car there may be a cal-
ibration mechanism that will allow you to adjust the economy readings by
10-15%.  Check the Bentley for your car.

I doubt that the TAP upgrade would affect the economy reading.  I would
be interested in hearing what you think the benefit of having the TAP
chip in your car is and if you had any problems with TAP.  Thanks!

Steve Buchholz
s_buchho@kla.com
San Jose, CA (USA)