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HELP! Check engine light comes on!

ProPhotog

Member
Joined
June 12, 2002
Messages
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City, State
Oklahoma City, OK
Year, Model & Trim Level
2002 XLS - KD5YKM
This might be long...okay, picked up an explorer, 133K miles, 4x4, 1994 model. (I've got 4 now). It's a sport model and the dang check engine light comes on after about 5-10 minutes of driving. I go and borrow a code reader and all it says is "lean left bank" "lean right bank". Okay, so it's running lean. It's not running poorly except that the gas mileage isn't great. What I have noticed...doesn't seem to have as much power after the check engine light comes on, I assume this is "limp" mode, but it doesn't affect driveability. I played tonight, and was checking the pass side O2 sensor and tugged on it...the connector TERMINALS came out of the plug. The ones on the O2 sensor completely separated from the plug...weird. SO...I pushed them back in and reconnected the O2 sensor. What I guess my question is...should I replace BOTH O2 sensors and hope this is the problem? Or could it be somewhere else? I tried to clean the injectors by using the IV drip method...I cleaned the AFM and even put on a new TPS because I've yet to run the truck on a scanner...I've only used a code reader. HELP???? grabgears(removethis)@hotmail.com
 



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I believe the codes were 172 and 176....lean left and right banks..oh I replaced the PCV valve, there is no vacuum leak that I know of and the plugs on the driver side were white...looked normal though, but showed the lean condition.
 






I would definately replace both front O2 Sensors. since you said the wires came off or something and not to mention it is throwing two codes for lean left & right banks. Also clean the MAF sensor. And clean the IAC as well.
 






Okay let me in...what's the brown wire mod? I might do that this weekend, replace both O2 sensors...but why does logic tell me if they are bad it would run rich????? there's only 2 O2 sensors on it anyway correct?
 






Before replacing the O2 sensors, check those connectors carefully. A bad connection can also cause those codes, and if the connectors are really bad (especially on the PCM side) then a new O2 sensor isn't going to fix the problem. And if the connector is the only problem, it might be cheaper than replacing two O2 sensors.
 






Originally posted by ProPhotog
Okay let me in...what's the brown wire mod?

Dead Link Removed

I would definately replace the O2 sensor with the wires coming out.

The reason your truck starts running bad after 10 min of driving is because it is going into 'closed loop' mode and it is relying on the signal from the O2 sensors to control the fuel/air ratio. If it is getting a bad signal, it will revert to a 'limp home' mode and the fuel / air ratio will be screwed up.
 






Just got done replacing the O2 sensors...now waiting for the computer to reset. I disconnected the battery for a while to clear it....I think. Anyway. what a ***** to get to those connectors. I appreciate everyone's help. I'll let you know if that darned CEL comes on again...:eek:
 






Where was your second o2 sensor? For the life of my on my '92 I could only find one. They sold me two at the store and I remember here that someone mentioned two but I can only find one on my car.
 






I might be wrong, but your model year might only have one on it...Mine's a 94, wife's is a 94, my other is a 93, and the beater 92 I have all have 2...honestly, I've never changed them on the 92 though so I couldn't tell you if there's one or two. Either way, the one on the driver's side is directly visable on the back of the downpipe, the other one is sort of hidden on the passenger side. right in front of and on top of the catalytic converter facing the front of the vehicle is the second one. It faces foward compared to the drivers side one. I accessed it through the crossmember near the transmission bellhousing.
 






OH I forgot

Took the exploder for a drive after replacing the O2 sensors...no CEL after putting over 10 miles of highway and city driving. Ran a lot better and I'm hoping this improves the crappy 9 mpg I was getting before. Thanks to those of you who helped.
 






My '92 only has one: in the Y-pipe right before the cats. I'm reasonably sure that '93 was when they went to two O2 sensors.
 






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