Got a CEL today P1179. Had just replaced fuel pump/filter, plugs/wires, air filter, and oil. Has been having rough hot starts for some time. Also noticed that the o2 sensors were showing a lean condition. Should i focus on the MAF/intake cleaning, or replace the o2 sensors up/down? Thanks in advance, this forum rocks!

 

MAF cleaning when stone cold with made for MAF spray. Air filter not dirty.

 

Still having issues with codes (particularity P1179 and P0451). I did a complete intake/MAF cleaning, but still throwing codes about once a week. One thing I did notice is that the O2 sensors are vastly different between bank 1 and 2. Bank 2 seems to run around double what bank 1 is showing. Should i focus on replacing the upstream sensors, or is there something that would cause this? Checked fuel pressure (already replaced pump and filter) and has a constant 32psi. Also what should i be looking at for the P0451 (purge valve?).

Thanks!

 

If you can see live data stream the upstream o2should fluctuate the numbers rapidly if not I would say replace, hard hot start could be fuel temp sendor

 

you may also want to check for a vacuum leak if the O2 sensors check out okay.