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      04-13-2010, 04:39 PM   #15
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Quote:
Originally Posted by vasillalov View Post
...but that does not matter much...

My understanding is that the O2 sim is a replacement for the actual O2 sensor that is for checking that the catalytic converters are up and running. The O2 sensor that is responsible for the fuel mixture adjustments is not removed, correct?

...so for as long as the ECU *thinks* that the catalytic converters are doing there job, it really makes no difference...
Not quite. An o2 sim is a device that manipulates the output signal of the rear o2 sensor. Typically, they reduce the max and min swings to a range the DME would associate with a fully catted exhaust system.

And while the front o2 sensors are the primary lambda sensors that influence fuel trims, the rear o2 sensors do indeed effect fueling as well. You can see this yourself by monitoring short and long term fuel trims while adjusting the o2 sim strength (or, in the case of Procede, the o2 modifier setting).

Which is why we are developed a CAN based "o2 sim" that doesn't adjust the rear o2 signals but rather just keeps the DME from completing its catalytic inefficiency test routines.

Shiv
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