Are these O2 sensors bad?

[CManT1914]

I was gonna test the sensors to see if they were bad, but I left my multimeter at home, and wasn't able to. My friend suggested just trying to clean them and seeing if that helped.

So I pulled my O2 sensors and my IAT sensor. Well my IAT was gummed up and had crap on it, so I sprayed it with some carb+choke cleaner. When I pulled my O2's, they looked like this:

I tried spraying them down with the cleaner and wiping them off, but they didn't really get any better. Can O2 sensors even get gummed up?

Anyway, when I put them all back in, I started it up and it idled smoother than it did before (no doubt because of the IAT), but when I drove it, it was bogging down around 2700 rpms. I figured the O2's were still wet, because the more I drove, the less it bogged, and after a few minutes it wasn't bogging as much. But it still lacks power, and although it is not throwing the old 181 and 191 codes (because I reset the PCM) I really don't think this fixed anything. Oh yea, I'm gonna check my timing today or tomorrow and make sure it's correct, as it's been off before, and it feels like it did when it was off. Anymore suggestions?

 

[HISSIN50]

w/o other info, the sensor itself looks ok. did you use a cleaner that is O2 safe? some folks have used a torch to clean the O2's (never tried it myself). a way to check if something might be O2 related is to compare 'deep in the pedal' runs vs WOT runs (the latter not using O2 input).

good luck.

 

[95WhiteVenom]

Easy way to check is by shaking it and if it sounds like a baby rattle then its dead. Since you got them off you might as well go ahead and change them. I just put some new Bosch ones on my car bout two weeks ago and they got rid of my problems.

 

[CManT1914]

HISSIN, so the readings from the O2's is not even used under WOT? So they shouldn't make a difference under WOT? I'll check it out tomorrow, I was to scared to get into it to hard yesterday. Thanks for the info, and Chris, in case I need to replace mine, where did you get the Bosch ones?

 

[mo_dingo]

HISSIN, so the readings from the O2's is not even used under WOT? So they shouldn't make a difference under WOT? I'll check it out tomorrow, I was to scared to get into it to hard yesterday. Thanks for the info, and Chris, in case I need to replace mine, where did you get the Bosch ones?

Yep, the O2 sensors are ignored at cold start and WOT. When the car is warm, and at part throttle, is the only time the O2's are used.
Scott

 

[Venom351R]

You cant clean 02 sensors, there either bad or good and if there bad just replace them. Like stated before since there off the car go ahead and just replace them.

 

[HISSIN50]

Scott hit it on the head.

i would add that O2's can still function somewhat decently, but do degrade over time. they oscillate from ~.1 to ~1.0 volt several times a second (constantly overcorrecting from the last reading since the A/F situation is often dynamic). as they age or get contaminated, their range can diminish and they can also switch more slowly. they still work, but not so hot.

 

[CManT1914]

HOLY CRAP o2 sensors are expensive!! Well since I already put them back in (not like they take forever to pull out again), I'm assuming I can use a multimeter to test them to see if they are still good? Do I measure for ohms or voltage? What should the measurements be? I'm not to good at electrical work so gimme some help here, lol.

EDIT: Never mind, I actually found some useful info in my haynes manual: Readings should vary from 0.1-volt (high oxygen, lean mixture) to 0.9-volt (low oxygen, rich mixture).

So according to that, any of those readings should be okay?

 

[HISSIN50]

EDIT: Never mind, I actually found some useful info in my haynes manual: Readings should vary from 0.1-volt (high oxygen, lean mixture) to 0.9-volt (low oxygen, rich mixture).

So according to that, any of those readings should be okay?

hmmm, that looks what i posted above you.

might re-read what i posted about the switching. keep in mind that many DMM's average the readings, which can make deciphering accurate voltage readings difficult.

yep, they are pricey (40 bucks a piece or so), but they should hold up alright, if the state of tune is decent. in the old days, EGO's were cheap but did not hold up too well. 6 of one, 1/2 dozen of another.

 

[xkuntrycowboyx]

MIL eliminators?

can someone help the stupid here and explain to me what they do???

I think that you plug them in instead of your O2 sensors, if you replace the factory exhuast and there are no holes to insert O2's into the exhaust, H or X pipe. ...Is this correct, and what do they do, just turn off the CEL???

 

[95WhiteVenom]

Bosch O2's

HISSIN, so the readings from the O2's is not even used under WOT? So they shouldn't make a difference under WOT? I'll check it out tomorrow, I was to scared to get into it to hard yesterday. Thanks for the info, and Chris, in case I need to replace mine, where did you get the Bosch ones?

Bosch O2 sensors $49.95 each from advanced auto.

 

[CManT1914]

UPDATE: I tested my ECT and IAT sensors.

Me ECT sensor had a voltage supply of 4.5v, so the wiring is good. It had a 3,500 ohms resistance, which is right on par, so I think I can rule out the ECT as being a suspect.

My IAT also had a 4.6v supply, so good wires. But at normal temperature, it was reading 19,000 ohms! It should be like 2,000 according to the Haynes manual. It DID have some gunk and crap on the prongs, so I cleaned it off, but didn't check it again.

I attempted to check my MAF, but my Haynes manual is showing the wrong connector for mine, it shows a round one, and mine is a rectangular one. The rectangular one in the manual it says is for the 4.6L SOHC motors. Does anybody know which of the 4 points on the harness and the MAF itself are the ground and positive voltage leads? On the MAF, they are labeled from left to right, A B C D. I'd like to test it too.

I didn't see any info in the manual about testing the IAC sensor, so I left it alone, anybody have information on that?

I didn't have time to test the O2 sensors, as I was doing this on my lunch break, but HISSIN, you said under WOT they are ignored anyway, well under WOT, it still runs like crap. So I don't THINK it's the O2's. Anymore advice?