Need help running rich!

[shovel]

Replacing the o2 sensor just because the vehicle is reporting lean and subsequently enriching is silly, there are a dozen different problems that could cause this condition and just replacing the sensor that reports the condition is literally "shooting the messenger"

The post-cat o2 sensor really, genuinely, no-myth-about-it is not used for fuel trim. Period. In fact it CAN'T be used for fuel trim. Think about it: there's a frickin catalyst right before the sensor, how would the sensor know whether o2 readings are skewed by the effectivenes of the catalyst at that moment?

Replace your fuel filter first, it needs it anyway by 30k miles. See if that corrects the problem. Then use a fuel pressure gauge on the port that exists for that very reason to diagnose the problem rather than just randomly throwing expensive parts at the problem in hopes of accidentally curing it.

[DifferentPointofView]

Originally Posted by shovel

Replacing the o2 sensor just because the vehicle is reporting lean and subsequently enriching is silly, there are a dozen different problems that could cause this condition and just replacing the sensor that reports the condition is literally "shooting the messenger"

The post-cat o2 sensor really, genuinely, no-myth-about-it is not used for fuel trim. Period. In fact it CAN'T be used for fuel trim. Think about it: there's a frickin catalyst right before the sensor, how would the sensor know whether o2 readings are skewed by the effectivenes of the catalyst at that moment?

Replace your fuel filter first, it needs it anyway by 30k miles. See if that corrects the problem. Then use a fuel pressure gauge on the port that exists for that very reason to diagnose the problem rather than just randomly throwing expensive parts at the problem in hopes of accidentally curing it.

Expensive parts? my o2 was like 40 bucks.

I'm not talking about the post cat sensor. I'm talking about the pre cat sensor. And you don't have to replace it, you just do a test, and if it tests bad, you replace the sensor, if it tests good, then you look elsewhere.

[nemesis]

check for vacuum leaks and evap system, either one will cause similar problems that you are seeing. One more thing, do you have an exhaust leak by any chance? that would do it too, even the smallest one.