2003 E46 330ci Lean Codes HELP!

[Xxmajesticxx]

Hi everyone,


First of all I am a newbie to these forums and I want to thank you all in advanced for any help I receive.


I have a 2003 330CI and I am getting lean codes and have a slight misfire. I have a full scanner that gives me all of the bmw codes but the only ones present are P0171 and P0174.


Now I replaced all of the vacuum lines so no vacuum leaks, the intake boots that always crack, the DISA valve, the PCV system is not bad, I have a new fuel pump and the fuel pressure is also good. I replaced the MAF and the oxygen sensors and still I keep getting the lean codes :


The codes pops up within a few minutes of start up. The strange part is that when I disconnect the MAF the I no longer have a misfire and I no longer have lean codes, only the code for MAF because it is disconnected. When the MAF is connected I get a steady reading from the upstrem oxygen sensors of close to .07 V That is extremely lean : When I disconnect the MAF I fluctuate between .2 to .8 which is about normal. I am stumped : I don't know what to do because I've been trying fix this problem for months : I need to pass inspection to renew my regi so I'm riding dirty now. Please give me some ideas. Do you think I may have an electrical issue? Thanks!

[autowa]

Intake manifold gaskets maybe? They can throw a lean code

[snaponbob]

Sounds like you may have already uncovered the issue --- MAF. Get some MAF cleaner (and NOTHING else) at a parts store, and spray the MAF. Do NOT blow it dry. See if that helps. If not, you probably need to consider a new MAF.

Others may have a better solution.

[MMKZ]

i have the same two codes for a 02 325i sedan and don't know where to start

[snaponbob]

Having just reread the OP, lean codes and misfires can go hand in hand. If the fuel is not being burned, the O2 sensors will see MORE oxygen. I have a friends 330xi in my shop so may hook up my Snap-On Solus and see if the data stream shows misfire counts. Anyway, if the plugs are old or somewhat fouled, potentially that MAY be the route of the problem.

[Xxmajesticxx]

Thank you guys for the help. I ended up changing the MAF sensor and resetting the codes and finally, no more lean codes :banana:


I finally got my inspection and renewed my regi. I had done a smoke test and all was good so I knew it wasn't vacuum related. I am just surprised that both bad MAF sensors did not show a MAF code.


Hope this helps some people with similar issues. Thanks again!