What do bad o2 sensors do?

epurdy2005 · May 19, 2008

Well I realized I was posting in the wrong section. Anyways I had to replace my oil pan because it was rusted out(yea).that job sucked...anyways had to have the exhaust bolts taken out at a shop because they broke off....Put the car back together and now it won't idle..

Here it goes...Start it up....runs pretty good...smells rich....idles fine though...I waited about 5 min. then took it out. Get into 4rth gear and check engine light comes on. Stay at 55 and every once in a while it cuts out for just a second. Then when you stop the idle just goes up and down and usually ends up dieing. But it also has alot of power after the check engine light comes on when your taking off. I tried putting a different MAF on it tonight and it help...I've tried running the codes and i'm having a hard time understand them but i think it said lean O2 on the left side. Any suggestions? Thanks!

Evan

HISSIN50 · May 19, 2008

Make sure the electrical connectors for the O2's are connected.

If it spits a code on one side only, swap the O2's and see if the code follows the original O2. If it does, replace that O2. If the issue doesnt follow the O2, there's a wiring issue in that O2 harness or something else is up.

If you spit lean codes for both banks, check the MAF, vac leaks, etc.

Good luck.

j_lutter31 · May 19, 2008

The O2 Sensor went out on my car a few years ago, it didn't send any codes, I don't remember if there were strange idling problems but I definitely remember that it took forever to get up to speed......it took almost a mile to get up to 70.....

ProKiller · May 20, 2008

j_lutter31 said:
The O2 Sensor went out on my car a few years ago, it didn't send any codes, I don't remember if there were strange idling problems but I definitely remember that it took forever to get up to speed......it took almost a mile to get up to 70.....

you might notice a slight idle hicup but nothing major usually.

BREWTUS428CJ · May 20, 2008

Just replaced a bad o2 on my friend's Bronco 408W, it was pinging when you floor it, and timing wouldnt fix it. idled fine, ran fine other than the detonation. We hooked up the tweecer and found the lft 02 doing nothing, it was just going to super lean when we got on it. Also: Post the codes you pulled.

desertcox05 · May 20, 2008

mine was throwing lean codes on both banks and a TPS code I cleaned the MAF replaced the K&N filter with a paper one and reset the puter runs great and no more CEL

epurdy2005 · May 20, 2008

The codes said O2 sensor lean on the left side and MAF has low voltage. But its smells very rich...I just don't think two things would go bad because the car was running fine before I replaced the oil pan..I'm thinking of taking it to the stealership but I really don't want to and can' really afford to. Stumped at this point.

Chythar · May 20, 2008

Sometimes problems like this come up by pure chance after you move things around. The sensor might have failed at this time even if you hadn't replaced your pan. Like Hissin said, swap the O2 sensors and see if you get a code saying O2 lean on right side. If so, the sensor went bad. If not, you'll have to check the wiring and see if anything got yanked when you pulled the pan.

As for the MAF, what did you unhook when you changed the pan? Did you disconnect any wiring? I would presume so, yuo gotta pull the engine up pretty far to change the pan.

desertcox05 · May 21, 2008

cleaning the maf is FREE it's a common prob with the sn's

epurdy2005 · May 21, 2008

yes!

Well after replacing the MAF from one auto parts store and not working I just couldn't see taking to the dealership and paying out my ass or replacing the 02 sensors.Finally did something right. I went to another auto parts store and bought a different one and success!.....................Just for future reference if anybody has MAF problems...It started off with loss of power because i noticed when i bought it seemed to cut off at 3,000 rpms and just wouldn't go much more but no check engine light.(I had never driven a 5.0 thought and didn't know what to expect) Then after the oil pan repair it wouldn't idle and ran really rich.

SVTtripleblack · May 22, 2008

Why not just clean the old MAF? They get dirty, but rarely go bad. Would've saved a lot of money.

mustang6tee8 · May 24, 2008

epurdy2005 said:
The codes said O2 sensor lean on the left side and MAF has low voltage. But its smells very rich...I just don't think two things would go bad because the car was running fine before I replaced the oil pan..I'm thinking of taking it to the stealership but I really don't want to and can' really afford to. Stumped at this point.

just fyi... it smelled rich because the computer read the O2 sensor running lean, so it injects a little bit more fuel to compensate for it.

Adam95GT · May 24, 2008

Just for the record. When my 02 was going out i had a lean code... smelt really rich. bogged unless i was at WOT... because when at wot it bypasses the o2's closed loop

What do bad o2 sensors do?

epurdy2005

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HISSIN50

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j_lutter31

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ProKiller

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epurdy2005

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Chythar

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epurdy2005

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