Now i don't know much about air/fuel stuff, but i recently got Uprev osiris standard which comes with cipher. and i got my base tune. after the tune i was throwing 2 codes...p2ao3, and p0138, the first one was regarding the o2 on the driver side exhaust manifold, and the second one was regarding the o2 sensor on the passenger side test pipe. My cats were removed pre-tune for test pipes.

Now all of a sudden I'm not getting a CEL, but when i check with cipher, the p0138 still comes up as DTC. but the other one doesn't....

NOW TO THE AIR/FUEL thing,
I wanted to data log with cipher to see what's going on, and mainly watching my air/fuel, it seems normal while on the throttle, and at idle, but as soon as i'm off the throttle(letting the engine slow the car) it leans out and hits 30?????
anybody seen this before??? this doesn't seem very safe to me

 

The codes are a separate issue. The last thing you mention - the AFR jumping to 30 when you let off the throttle - is 100% normal. The engine is not being fed gas under those conditions, and so it reads lean. It's perfectly normal and perfectly safe.

 

Ok cool, thanks alot, i think my blood pressure's back to normal now that you said that. I had a slight feeling that it "could" be normal, but wanted to know forsure.

thanks again

 

The CEL going away could be a random tripping that gets cleared when the power is turned off. The code still being in your cypher program is probably there from memory. Have you tried clearing the code in the software?

 

The factory ECU uses the pre-cat 02 sensors to measure the air fuel ratio, while the post-cat sensors are there to monitor catalyst function. In other words the pre-cat sensors are more important. That could be why you are still getting a code for one of the post cat sensors but are not throwing a CEL.

As mentioned, the lean A/F when you let off the throttle is normal. This is usually referred to as "decel fuel cut".