Mysterious idle problem with code on.

[toupissan]

hello everyone

i have kind of a weird problem. my 99 explorer sport has had a cold start problem with a lean code on bank 1 forever. we change the o-rings,upper and lower, which fixed the problem. now i have a new cel code p0420: cat efficiency under threshold which cause the truck to hesitate on quick acceleration, and idle roughly when i stop at a red light. the thing is everytime i disconnect the battery and get rid of the cel, everything is just fine. idle is smooth and the acceleration is perfect with no hesitation until... the light comes back on.

has anybody experienced the same problem? and any idea how to fix it?

any help or advice will be greatly appreciated.

p.s. it's a v6, sohc with 100k.

 

[jremington59]

This may help you.

http://www.obd-codes.com/p0420

I don't understand the difference in running after you reset the cel. You need to get a reading on the o2 sensors on that bank....

 

[toupissan]

i notice the difference everytime i reset the code. i had it read at the mechanics, and they told me the code is for the post cat o2 sensor and said cat efficiency below threshold... it could be the cat or the sensor, or a lot of other stuff. my problem is why does it run better without the code? is there a special meaning to it? i'm trying not to go and start replacing parts, as some, like the cat converters are very expensive.

 

[toupissan]

does anybody have any idea? i'm gonna have to pass inspection in a month. really would like some pointers as to where to start. especially since i can't return a cat converter for a refund...