A/F and reading it properly.
Thread Starter
Staging Lane
iTrader: (1)
Joined: Nov 2008
Posts: 76
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From: Southern Illinois
A/F and reading it properly. I had my car tuned by Frost with a mail order tune and then calibrated my wideband and af is showing a constant 14-15 depending on where im at in my throttle. Im by no means an expert but always thought af should be a bit more in the 11-13 range. I did take my wideband sensor out of the y pipe and recalibrated it after the tune. I feel that I am in fact getting a true reading. I have no cats and long tubes and intake. Nothing else is done to the engine. Steve at Frost tuning informed me that my af is correct but that the closed loop system is why I am confused. I am confused so please school me. He did the mail order tune and decided to get hateful with me since I questioned my tune so any help is appreciated.
When your car goes into closed loop, the computers use the o 2 sensors to adjust fuel to around 14.7, which is why you jump from 14-15. When you floor the car (WOT), it goes to open loop and that is when your afr will be in the 12-13 range for a N/A car.
At higher map pressures your equivalence tables will command rich, also the throttle positron can dictate power enrichment which can also command rich. If neither if those tables are active(maybe others), the engine tries to maintain 14.7 ish with o2 sensors. You could always download efilive software for free and begin learning why your car does what by looking through and understanding the tables. Just a suggestion. Searching the table names on this and efilive's forum will give you all the answers you have.
Im guessing that my a/f is correct then?
Verify that at full throttle the AFRs are where they should be based on your application (12s NA, 11s FI).
