O2 Sensor question

[v8318cid]

Ok, I'm trying to sort out a problem with the O2 sensor on my 92 2.3L. I've chased down all the problem codes in the system and eliminated all but the 172 code (O2 lean). I've checked for vacuum leaks, replaced the throttle body and upper-to-lower intake gaskets, and replaced the EGR valve and gasket. I still get a 172 code regardless. Every now and then the MIL will not turn on, but its rare. Always turns on after about 1 mile of driving. Also get the same code if I disconnect the O2 sensor, although that isn't really unexpected. The engine runs the same either with or without the sensor. The wiring harness looks good. I've also checked the Tech page for troubleshooting the sensor, but I cannot figure out the exact procedure for checking the wiring. The diag page talks about a picture or diagram of how to properly hook up a volt meter, but there doesn't appear to be a link or a picture to check. Any ideas? By the way, does anyone know if the ECU uses the speed sensor just above the speedo cable to control engine performance or is that sensor something to do with the RABS controls? Thanks.

 

[bluebombersfan]

did you try a new o2 sensor

you did alot of other work but never mentioned if you tried a new 02 sensor that would be my first move

 

[scotts90ranger]

actually, my first step would be to check for exhaust leaks, remove the stupid pre heater thing from the exhaust manifold so you can check for cracks in the manifold, if it is cracked that would let air in (I know, not what you would expect) and the O2 sensor would think the engine is running lean. since the sensor is mounted in the manifold the flange bolts shouldn't cause the problem but if the manifold gasket is shot that could. If there aren't any cracks visible (if you can't see them it's probably not the problem) then change the oxygen sensor

 

[v8318cid]

No, I have not tried replacing the sensor yet. Had to eliminate plenty of other known problems first. I haven't positively confirmed it yet, but I think I found what was causing the problem. Apparently the O2 sensor on my truck grounds on the starter housing. There is a wire attached to it that was somewhat loose. The last time I was under the truck I tightened the bolt. Not only did my starter stop dragging as bad, but the MIL stopped coming on as well. Still need to pull the codes to be sure. Seems like a strange way to wire the sensor though. Whomever had this truck before me beat the living daylights out of it so who knows? Its already missing the catalyst and someone tampered with the rear dif (speedo was WAY off...). Numerous other problems as well. Thanks for the input.