Reading Lambda or O2

[Lordalfa]

Reading Lambda or O2 is tricky. I will explain for petrol driven cars.

 

1. You need 14.7 parts of air to 1 part of fuel to give a burn that is of maximum power. This is in theory only.

 

2. However on the practical application, you need to inject more fuel for more torque. Because of the fuel nature and cylinder flows, spark flame front etc, you need more fuel for torque and protection. The leaner the burnm, the hotter the gases, the hotter the gases, can your engine components take the heat before a meltdown.

 

3. There are 2 types of O2 sensors. Narrowband and Wideband. Narrowband is what is commonly installed in our cars. Wideband is for tuning. Narrowband is mentioned can only read from 13 to 15. Wideband can read from 6 to 22. So it can really tune from very rich or very lean conditions.

 

4. Typical readings of lambda for WOT is, NA:13.5, FI-12.5. Normally these numbers are a lot richer as the manufacturers protect the engine with a rich burn. Experience shows that when you plug a piggyback or aftermarket ECU on a WRX and tune to 12.5 at WOT, it shows significant improvement for economy.

 

5. Fueling is only part of the power/torque equation of the engine. You need to take care of spark timing. Lambda alone will not increase power or torque. You timing to fire the spark is important.

[Lordalfa]

Make your own O2 sensor at http://techedge.com.au.

 

I have one. If anyone wants to use, make sure you place this before any cat. But if you are not tuning the car, you can forget about using it.