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O2 Sensor voltage readings everywhere!
Posted: Sun Aug 24, 2003 12:24 am
by Gordo
Hi all. I have a 92 Legacy turbo and decided to get some readings off my O2 sensor today to get an idea of my A/F ratios. After warming it up for 15 minutes I took it for a spin and kept an eye on my meter. I was astounded after seeing basically the whole range from 0-1v almost. At no load ie. coasting I was seeing 0.1vdc and at full boost which is around 10 psi I see 0.85vdc! Yikes. Cruising numbers seemed a little better at between 0.4 to 0.6vdc. Is this thing running open loop? Is my ECU messed up? I have no check engine light and it seems to running ok although I'm always wishing the car had more balls than it does. That comes later I guess, after I figure out how to monitor and control my A/F ratio, bypass the boost limiter, etc. etc.
Any thoughts on the O2 sensor readings gents?
Posted: Sun Aug 24, 2003 5:16 am
by ciper
That sounds exactly right if you ask me.
Running a perfect ratio has a fairly large range of voltages, the rich and lean side are very compressed.
O2 Sensor Output [Volts]
-------------Exhaust Gas Temp
[Deg K]---773.15-------1023------1173
[Deg C]---500---------750---------900
10.3-------0.998-------0.930-------0.874
11.8-------0.975-------0.906-------0.847
13.2-------0.942-------0.864-------0.788
14.7-------0.830-------0.742-------0.659-------Rich end of Stoichiometric
14.7-------0.101-------0.133-------0.153-------Lean end of Stoichiometric
16.2-------0.044-------0.058-------0.067
17.6-------0.028-------0.037-------0.042
19.0-------0.018-------0.024-------0.028
Looks like under full boost you actually need slightly more fuel, best power is made with rich ratio of 12.7 if I remember right.
Also do you have an EGT? You may be running WAY too hot (with such lean high boost ratio)!!!!
EGT
Posted: Sun Aug 24, 2003 2:30 pm
by Gordo
Nope, I haven't any indication for EGT yet. Where is it? Any ideas on how I can make it run richer besides ECU tuning? I've bypassed the solenoid for boost control completely. I had just capped the ports and gone with a makeshift manual boost control using an adjustable relief valve (poppet style). By the way, thanks for all those numbers! Excellent.
Gordo