Civic-EG.com Forum 3.3.1

- Tue Dec 08, 2015 3:25 am #357810 So had a debate with some guys at work.

They'r saying if you tune an engine with a Engine Management System you can remove the O2 sensor (stock and wideband) from the exhaust because the EMS is regulating the fuel/air mixture and there is no need for an O2 sensor any more..

Is this true????? I been doubting them all this time because IMO the O2 is a pretty important sensor EMS or not... Plus they did some pretty dumb things with their cars in the past and damaged alot of things with their so called "know how" skills. So i was wondering if they was right this time or not???

"If you have poo, fling it now"!.

- Tue Dec 08, 2015 4:27 am #357811 I think they're full of it. You can regulate the air/fuel mixture all day long though the ECU or piggyback system, but all it's doing is crunching numbers and praying unless you read the O2 sensor. That's what tells the system if you are running too rich or lean. If you don't have that data, you're tuning blind.

[suspendedHatch]

- Tue Dec 08, 2015 9:02 am #357812 You tune with a wideband O2, but once it's tuned, you don't need an O2 sensor and you can remove it if you want. Your car will be running in "open loop" which means reading off the fuel table and not making any corrections based on O2 readings (there are still corrections for air temp, coolant temp, rapid throttle position changes).

A car running the stock ECU Needs O2 sensor feedback. It's one tune for all cars regardless of where/how they're driven and what condition they're in. That's not to mention the inevitable variation between any two engines coming off an assembly line. The ECU sprays fuel according to the fuel table, then checks the O2 sensor reading and makes an adjustment within what's allowed (somewhere around 15% in each direction of any given cell in the fuel table).

When you get your car tuned, it's specific to your exact engine in the condition it's in. A good tuner will get it to 1-3% (desired fuel ratio vs measured). Narrow band O2 feedback isn't necessary or particularly helpful. For street driving I prefer O2 feedback using a wideband (on an ECU that can do it of course).

Short answer is they are correct except for the word "regulating". With O2 feedback it's regulating, without it's just using the tune and not making an O2 correction (though it shouldn't need to if the tune is any good).

- Mon Dec 14, 2015 5:09 pm #357859 Thanks for the feedback guys
suspendedHatch that was some good info, so you can remove the wideband.
but i don't think i trust my tuner that much to run my car without it especially because its a daily driven car and a pretty expensive engine

"If you have poo, fling it now"!.