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K&N Filter and Chip in a 1993 318i



Back about a week ago I posted a message "Another Tire question?".
In the blurb I mentioned that I had installed a K&N air filter and
a chip in my 1993 318i. I received more questions about the filter
and the chip then I received answers to my tire questions. So here
are my experiences.
     
I purchased both parts from a local shop. The K&N filter cost was
$44 Canadian (.73 US = 1 Canadian) and arrived after a couple of
days. The performance increase was not noticeable except that
subjectively the engine felt smoother and a bit stronger above 5900
rpm.

The AutoThority chip arrived after a couple of weeks. I was told by
the shop that the delay was caused by the part having been shipped
to an old address. Now the problems really started. The
instructions were generic for several makes and models. The
location given for the control unit was some where near or in the
fire wall on the passenger side of the automobile. After tracing a
thick bunch of wires around the dash and pulling off a panel or two
I managed to locate my ABS control unit. Replacing the panels and
looking under the hood I found I thicker bunch of wire leading to
a foam rubber cover under which I found a trap door which when open
exposed the correct control unit. At this point following the
instructions the unit was easily removed.

Next step opening the control unit by bending back 4 breakaway tabs
(no fooling the BMW warranty police) and removing 8 screws. Pity
some models as they don't have the screws and they are told to put
it back together using rubber bands! 

Next big problem, the insides are completely different then the
instruction. Where there should be two boards there was only one
which was covered by surface mounted components and the EPROM was
soldered in without a socket, definitely the wrong part! As it
turned out BMW had exchanged the unit for the new style under
warranty repair. A call to AutoThority confirmed that my control
unit was a 1994 unit. They also promised to de-solder and remove
the current chip, replace it with a socket and a new chip. As they
were not equipped to fully test the unit after these modifications
and I do not trust US-Canadian customs (free trade or not) and I
was going to a driving school next weekend, I opted to get the new
chip Fed-Xed to my house. When the new chip arrived I very
carefully de-soldered the chip, replaced it with a high quality
socket, coated the socket and the main connector with a special
chemical to eliminate any possible future electrical contact
problems, installed the new chip, re-install the unit. The new
instructions were much better for the second chip.

Now the results for the combined K&N filter and chip: 
More torque across the complete range, very smooth all the way up
to 6800 red line. A real Miata killer. 

Down side: 
The need to use 92 octane fuel (instead of 90). About 8% higher
fuel consumption ( it could be a heavier right foot). At 3/4 throttle
torque surges slightly.

- ----------------------------------------------------------------- 
 Ryan S. Raz     
 Morphometrix, 120 Adelaide St. E., Unit 2, 
 Toronto, Ontario, Canada M5C 1K9
 Tel: (416)361-6239   Fax: (416)361-3162   Email: morph@io.org
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