This is a bit of a continuance from a thread titled Performance Upgrades in the "internals & engine" thread, but I think this would be a better home for what i hope to discuss. Basically I found a link to a partial of the intake test that SCC ran sometime back. The full write-up can be found in the Feb '09, Vol 21, No.02; however there's a decent amount of info in the article found on this link.

http://www.sportcompactcarweb.com/te...nch/index.html

I understand what they are saying regarding Mass Air Flow and the numbers they recorded are actually very interesting, but what I would like to know is what they are doing to "reset" the ecu so that it "learns" a new performance curve as opposed to the old regular curve? Also, how is the MAF sensor get "tricked" into leaning out the air/fuel mixture?

Any additional comments or insights on this would be great...plz discuss

 

I didn't read the whole article, but I believe Subaru ECUs have the ability to "learn" based on driving habits. Honda ECU's are different. They use the sensors most of the time to control fuel and ignition, but can also switch into a closed loop mode where the ECU delivers fuel and spark right off of a pre-determined table designed by Honda (this is the table that tuners tune).

Basically, to answer your question, if the engine can sense more air being delivered, it will dump in more fuel to balance the mix. This, of course, needs a Mass Airflow Sensor to do, which most older Hondas do not have.

 

I bet Hondas have some ability to learn also. Clearly they learn the behavior of the idle system (based on the procedure for setting base idle). Cars without a MAF sensor would "learn" their corrections to the fuel map based on the feedback from the primary O2 sensor.

Normally a learning system like that has authority to make only a small correction to the base map.