Service Engine light wont go away - Bank 1 & 2 too lean?

Sean172 · 12-13-2011, 05:24 PM

Help!! My engine began running rough and the service engine light has been on. I have cleaned my Mass Air Flow sensor, been throught a dozen bottles of injector cleaner, and I just replaced the two upstream oxygen sonsors. The engine still idles rough and the OBD code shows Bank 1 sytem too lean, Bank 2 system too lean, as well as a slew of random misfire codes. What the hell!!!

What should I do next? Any suggestions
Thanks

thekidba · 12-13-2011, 05:31 PM

Same thing happened to me. I have a thread about it somewhere here, but it turned out to be the MAF. Cleaning it doesn't work after awhile and it needed to be replaced. Replace those hoses if they're brittle since your in the vicinity. gl

Sean172 · 12-13-2011, 05:35 PM

I cleaned it twice, the first time I didnt see that there were two sets of wire filaments is the sensor and I only cleaned one. After I cleaned it correctly the car ran much better, I almost thought I had it licked but it started idling poorly again. But I think I am on the right track with the MAF sensor. Thanks

TxZHP04 · 12-13-2011, 05:41 PM

More than likely you have a vac leak. Quit messing with the MAF and find the leak.

Sean172 · 12-13-2011, 06:57 PM

How do find a vacuum leak?

jordangreen21 · 12-13-2011, 08:08 PM

So I am having a similar problem... I was running catless headers and everything was running fine. I installed my stock headers again and am having these same codes thrown. Everything was fine before... is it just a coincidence that I am now having a vac leak because that is what I keep seeing people say about having similar problems.

TxZHP04 · 12-14-2011, 07:43 AM

Quote:

Originally Posted by Sean172

How do find a vacuum leak?

A professional smoke test is your best bet. Sometimes you can find these leaks through visual inspection or strategic spraying of volatile fluids around the engine bay. Plenty of discussion of this topic including a thread on how to build your own smoke machine, you just need to search them out. Cracks in the intake boot between the MAF and TB are pretty common as are cracks in the numerous hoses attached to the intake manifold. A leaking DISA gasket is also relatively common.

Sean172 · 12-14-2011, 01:41 PM

I followed the suggestion about tracking down a vacuum leak and BINGO!! Both of the boots on either side of MAF sensor were dry rotted on the back sides out of sight. The rear one has a branch off to the idle control valve, that one had a huge hole in it that I could fit my index finger in. Getting that one off looks like a bitch, it has a hose clamp holding it on which is buried under the throttle body. Is there a DIY on this??
Thanks for the tips!!
Sean

CylonRed · 12-14-2011, 02:26 PM

Quote:

Originally Posted by Sean172

I followed the suggestion about tracking down a vacuum leak and BINGO!! Both of the boots on either side of MAF sensor were dry rotted on the back sides out of sight. The rear one has a branch off to the idle control valve, that one had a huge hole in it that I could fit my index finger in. Getting that one off looks like a bitch, it has a hose clamp holding it on which is buried under the throttle body. Is there a DIY on this??
Thanks for the tips!!
Sean

Many DIY's - not that hard to do but I did need a mirror to see to make sure I lined up the intake properly.

12-13-2011, 05:24 PM	#1
Sean172 Registered User Join Date: Jul 2009 Location: Mahopac, NY Posts: 26 My Ride: 03' 330i View My Garage	Service Engine light wont go away - Bank 1 & 2 too lean? Help!! My engine began running rough and the service engine light has been on. I have cleaned my Mass Air Flow sensor, been throught a dozen bottles of injector cleaner, and I just replaced the two upstream oxygen sonsors. The engine still idles rough and the OBD code shows Bank 1 sytem too lean, Bank 2 system too lean, as well as a slew of random misfire codes. What the hell!!! What should I do next? Any suggestions Thanks

12-13-2011, 05:35 PM	#3
Sean172 Registered User Join Date: Jul 2009 Location: Mahopac, NY Posts: 26 My Ride: 03' 330i View My Garage	I was thinking the same thing, I cleaned it twice, the first time I didnt see that there were two sets of wire filaments is the sensor and I only cleaned one. After I cleaned it correctly the car ran much better, I almost thought I had it licked but it started idling poorly again. But I think I am on the right track with the MAF sensor. Thanks

12-13-2011, 05:41 PM	#4
TxZHP04 Registered User Join Date: Feb 2006 Location: DFW Posts: 5,731 My Ride: ESS TS2+ ZHP View My Garage	More than likely you have a vac leak. Quit messing with the MAF and find the leak. __________________ 04 IR 330i ZHP \| ESS TS2+ SC \| MagnaFlow "headers" \| KMS 3.64 LSD \| AST 4100 550/650\| APEX ARC-8 18x9 \| H&R front sway bar \| Vorshlag camber plates, RTAB limiters \| TMS subframe & swaybar reinforcements \| UUC SSK & DSSR \| UUC TM & TME \| BW motor mounts \| Dinan strut & shock tower bars \| vaio 4-bolt oil pump

12-13-2011, 06:57 PM	#5
Sean172 Registered User Join Date: Jul 2009 Location: Mahopac, NY Posts: 26 My Ride: 03' 330i View My Garage	How do find a vacuum leak? How do find a vacuum leak?

12-13-2011, 08:08 PM	#6
jordangreen21 Registered User Join Date: Oct 2010 Location: North Carolina Posts: 165 My Ride: e46 m3 View My Garage	So I am having a similar problem... I was running catless headers and everything was running fine. I installed my stock headers again and am having these same codes thrown. Everything was fine before... is it just a coincidence that I am now having a vac leak because that is what I keep seeing people say about having similar problems. __________________ D2 Racing Sport Suspension ~ aFe CAI ~ AA Tune ~ Orion AEs ~ Topspeed Exhaust ~ Euro Headers ~ UUC SSK Evo 3 and DSSR ~ 15% Tint Windows and 50% Windshield

12-13-2011, 05:31 PM	#2
thekidba Registered User Join Date: May 2011 Location: Long Island Posts: 37 My Ride: 2000 323ci View My Garage	Same thing happened to me. I have a thread about it somewhere here, but it turned out to be the MAF. Cleaning it doesn't work after awhile and it needed to be replaced. Replace those hoses if they're brittle since your in the vicinity. gl

12-14-2011, 01:41 PM	#8
Sean172 Registered User Join Date: Jul 2009 Location: Mahopac, NY Posts: 26 My Ride: 03' 330i View My Garage	Found a leak in intake boot I followed the suggestion about tracking down a vacuum leak and BINGO!! Both of the boots on either side of MAF sensor were dry rotted on the back sides out of sight. The rear one has a branch off to the idle control valve, that one had a huge hole in it that I could fit my index finger in. Getting that one off looks like a bitch, it has a hose clamp holding it on which is buried under the throttle body. Is there a DIY on this?? Thanks for the tips!! Sean

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