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Old 04-03-2012, 11:31 PM   #182 (permalink)
mja1
EcoModding Lurker
 
Join Date: Mar 2012
Location: Houston
Posts: 46

truck - '06 Chevrolet Silverado WT
90 day: 22.65 mpg (US)
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Quote:
Originally Posted by 2000mc View Post
i was confused too doax, just gotta buy into his logic to see the explanation....
and i think the 'if' will be over in about 2 seconds
guys, I apologize about my poor explanation of things, let me make it in the simplest terms I can.

The frequency at the MAF is the same with or without the CAI. The ECM uses this frequency to force a commanded AFR at the O2 sensors.

The MAF will read the same frequency in hertz as before, but with a slightly larger volume of air. The O2 sensor will force a slightly lean condition (*vs a measured/actual AFR*) from what is being commanded by the ECM (unless a large enough volume of air is sensed by the MAP to force engine into open loop and/or change fuel trims, and a number of other factors), if you read it off a tuning device it will say the O2 sensor is what it should be at '14.7' lets say. But this isn't the actual its just being commanded by the ECM. That reading, if you put a wideband in the same exhaust will read a slightly higher AFR than *what the computer is telling the O2 sensors*.

If the ECM/car has stock widebands in the system, like a stock forced induction car, this will be prevented, also if there is no MAF on the car. If you don't believe me then go try it yourself, the MAF frequency should be tuned for the increased air volume of the CAI, when this is done then yes all the warm air vs cold air thermo engine theory that has been talked about becomes true.

...the actual measured AFR will be 5-10% (or on extremely large engines as much as 15%) leaner than what the ECM is commanding.

Last edited by mja1; 04-03-2012 at 11:47 PM..
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