O2 sensors and IAC

[Kinarfi]

Checked my O2 sensors today, they were both good, Seimans VDO 5WY3173A with 7M12 stamped on the shoulder of the 22mm hex head.

Learned something I thought was interesting, when cold, the white lead for power measure about 6 ohms and the sensor lead measure open. If you power it up 12 volts, it draws 2 amps. As it was heating up, I was measuring resistance and saw the resistance go from open to zero to negative. That only happens when you are measuring a voltage with your meter on resistance.

The output appears to be a voltage from about .65 volts to - .025 depending on which way you hook up your leads.

On mine, when in free air or with air from my air compressor blowing on it, it measured -.025 volts, when I lowered into a can with gasoline in it, not into the gas, just above it, the voltage went to .65 volts, when I blew on it, it went close to 0 volts, when exposed to butane gas from a lighter, not lit, the voltage went from -.025 to about -.010, but I don't how much gas I was getting on it, shut have tried a lit lighter, but I didn't think to.

I have been having a tough time starting my Trooper, which is why I was checking the O2 sensors and I pulled the IAC and after cleaning it good, inside and out with brake cleaner fluid, I plugged it back and had my wife turn the key on while I watched the IAC. It ran and moved the "bullet" up so far that I couldn't put it back in. To get it back down, I had to squeeze it while my wife turned the key on and off several times, I could keep it from coming out any further, but couldn't get it to go back in until I opened the throttle and blocked it open. Then it backed off and I installed it.

After I got my Trooper running, warmed up, driven around some, and parked in the garage, I unplugged the IAC to see if it starts up OK after it cools and has set for a while. If it does, I'll cover the terminal and leave it that way.

Kinarfi

[ricksrb]

Checked my O2 sensors today, they were both good, Seimans VDO 5WY3173A with 7M12 stamped on the shoulder of the 22mm hex head.

Learned something I thought was interesting, when cold, the white lead for power measure about 6 ohms and the sensor lead measure open. If you power it up 12 volts, it draws 2 amps. As it was heating up, I was measuring resistance and saw the resistance go from open to zero to negative. That only happens when you are measuring a voltage with your meter on resistance.

The output appears to be a voltage from about .65 volts to - .025 depending on which way you hook up your leads.

On mine, when in free air or with air from my air compressor blowing on it, it measured -.025 volts, when I lowered into a can with gasoline in it, not into the gas, just above it, the voltage went to .65 volts, when I blew on it, it went close to 0 volts, when exposed to butane gas from a lighter, not lit, the voltage went from -.025 to about -.010, but I don't how much gas I was getting on it, shut have tried a lit lighter, but I didn't think to.

I have been having a tough time starting my Trooper, which is why I was checking the O2 sensors and I pulled the IAC and after cleaning it good, inside and out with brake cleaner fluid, I plugged it back and had my wife turn the key on while I watched the IAC. It ran and moved the "bullet" up so far that I couldn't put it back in. To get it back down, I had to squeeze it while my wife turned the key on and off several times, I could keep it from coming out any further, but couldn't get it to go back in until I opened the throttle and blocked it open. Then it backed off and I installed it.

After I got my Trooper running, warmed up, driven around some, and parked in the garage, I unplugged the IAC to see if it starts up OK after it cools and has set for a while. If it does, I'll cover the terminal and leave it that way.

Kinarfi

around here if you blow on it and it goes above .08 it means your above the legal limit(LOL)

[rocmoc]

Now that is funny rick!

rocmoc n AZ/Mexico

[jamesrulz]

Your 02 sensor should not cause hard starts because the computer should be in an open loop which means that the computer is using a pre programmed fuel map and not looking at the 02 sensors. Also your sensors need to be hot to be tested some people use a torch but you can hook up the 2 wires on the sensor that are used to pre heat the sensor with 12v to get the system into a closed loop quicker. My trooper used to start bad and surge at idle but it was because it went for a swim and the computer isnt sealed up at all. Anyway hope you find it