Dynomometer Test Problems

[proteman]

I ran a dyno test on a 2002 Mazda Protege ES which consistently ran an
Air/Fuel ratio of 14.8 (too lean) across most of power band, then all of
a sudden went rich above 5000 rpms. Car is completely stock except
for K&N panel air filter and MazdaSpeed Axle Back Exhaust. I changed
spark plugs to Bosch Platinum 2 about 1 year ago, don't know if this
could cause problems or not. I have not noticed any pinging or knocking.
Thought it could be oxygen sensors, but I am not getting check engine
light. Person running dynomometer said that it was the strangest thing
he had ever seen. Have no idea what is causing this?http://www.msprotege.com:8080/smilies/dunno.gif

[xelderx]

You can thank Ford for that. Did you reset the ECU after you did the modifications. Might help a little, but our ECU's are known for dumping lots of fuel at higher loads. The major shift in A/F ratio is when the ECU switches between closed loop (reading sensors) and open loop (preset fuel maps)

[proteman]

Resetting ecu didn't change results, did 3 pulls.