Call for help- misfire and lean bank 2

[1fast03pony]

Guys- im a few days away from installing my KB, and this happens

I put in my full bbk exhaust last weekend. Longtubes, o/r X with my existing magnapacks.

On cold starts, she stumbles for a good 3 minutes. Its a clear surging of power while driving and it just feels like ****. Then she'll even out after a while. I just filled up with fresh gas so im gonna see tomorrow if she does it again. However....
My light tripped again (not cats this time) and it read p0174 which is the lean bank 2 code. What do I check, and should i even worry since ill be putting in the KB with the KB chip, and a custom dyno tune coming next week?

I cleared the code with the xcal2

EDIT

I just did a quick search, and I shouldve mentioned that i recently replaced the drivers side front o2 sensor because the stock one was cross threaded in my old x pipe. Can this mean the o2 sensor is bad? Its brand new bosch.

 

[Mike97gt]

bank 2 is the drivers side.. so if your 02 sensor is not threaded in properly that can cause issues like this.. another possiblitity is a misfire on bank 2 is causing that bank to read lean because of all the unburned oxygen being dumped from the misfire. Sometimes you will not get a misfire code because the misfire monitor was not ready, if the battery was disconnected or the keep alive memory was recently reset then the misfire monitor might not work.

 

[fastangboi]

check out your spark plugs and make sure they are doin ok.

 

[nl mex]

I've struggled with a problem similar to this, but mine has to do with one or more of the coils being bad. I need to get around to fixing it.

 

[Stang|ess]

Replace the o2 sensor with an OEM ford.

Are your LTs ceramic coated? I've been reading that if you dont get them coated, it will cause a CEL until the pipes get hot

 

[triggz]

Swap coils and see if the problem follows to the cylinder you swap with. Then swap injectors and see if it follows that.. If thats no help, try a compression test on (at least) that cylinder, the 2 near it, and for reference one on the other bank. FWIW, the last romeo engine I did a comp check on showed 180psi.

Nothing wrong with running a bosch sensor, thats what you're buying from ford with a motorcraft logo on it.


What stang|ess is referring to is the LTs have no pre-heaters (that first set of cats) and it takes the exhaust temps longer to reach the operating range of the O2s.

 

[Mike97gt]

I just re read this and now I see there is a new 02 sensor on the drivers side that is not cross threaded ?

Ok well that sensor SHOULD be ok, 99-100 times a code like this is not caused by the 02 sensor itself.. since you said it feels like it's misfiring then it probally is on bank 2. this is why you are getting a lean reading from that bank.. When you get a misfire you are dumping unburned 02 down the exhaust, since the sensor can not see the unburned fuel it sees the exhaust gasses as lean..

you need to figure out the misfire, mot common causes of a misfire on these cars is a plug or coil