I was wondering if any one has numbers that the O2 sensor and MAP sensor display at idle. My car is a 1991 HB d15b2. My o2 sensor goes high .690-.700(stays there) volts at idle when it cools off. The map reads .895-.915 volts at idle. Just wondering if these are normal numbers for a stock engine. Had car inspected fail emissions, told guy car must be really warm to pass or o2 sensor will go into open loop(won't flick back and forth), hence high emmissions. seems the o2 is reading rich condtion at idle(not enough air) to much fuel. Any numbers or where to find will be greatly appreciated.

Thanks

 

Any help will be appreciated.
Thanks.

 

The oxygen sensor should switch
lean to rich
rich to lean
lean to rich
rich to lean

Drive your car for a while, freeway would be best for at least 10 minutes
so the car can go into closed loop
Get a graphing multimeter to see the pattern
It should be more or less like a rollercoater, it will go up and down in curves
It should switch pretty quick, if it takes a while then your sensor is bad

If i remember correctly, the middle point is .5 volts
Highest is about .8 volts
Lowest is about .2 volts