OK so it's been a while but I'm still dealing with this problem but have done much since. The P0313 code has gone away.
The P1092 has persisted.
HISTORY
Since originally deciding to give the car a large 60K tune up, I've replaced the following within the last 3K miles that I feel would contrbute to solving the problem:
*New Valve Cover Gasket
*Oil & Filter Change [Total Quartz INEO MC3 5w-30]
VANOS Seals Replacement [Seals & VANOS Body Gasket]
NGK Iridium IX plugs
Fuel Filter
CCV Valve & Hoses
Coolant drain & fill [BMW Coolant & Distilled Water]
New OE BMW air filter
New Pre-cat Bank 1 O2 sensor replaced @ 86.5K miles by dealer, prior to me taking ownership of the vehicle.
Other items that should have no bearing on the code are:
New Brake Pads all around and new rotors up front
Brake fluid flush
New Transmission fluid [Valvoline DEX VI & filter | Drained and filled 2x]
Drain and fill of front and rear differential with OE BMW fluid [Castrol XAF-XJ]
Drain and fill of transfer case with OE BMW fluid
Drain and fill of power steering fluid with ATF
New cabin air filter
New OE 17" size tires
As far as service goes:
2 Fuel System Cleaners [20z Chevron Techron Concentrate & 15oz Redline SI-1]
Reset throttle adaptation
Cleaned MAF sensor with CRC MAF Sensor Cleaner
Cleaned ICV, DISA & Throttle body butterfly valve
LubroMoly Ventil Sauber via the brake booster line to clean top end
In removing the air ducting to clean the intake components and replace the CCV, I checked the hoses for cracks but found none. I paid attention to the elbow/accordian that shoots off to the ICV but it was OK.
The items I starred (*) above are what I believe might possibly be causing the condition. Although I torqued the valve cover gaskets down to spec, it could possibly still be leaky. I have not had a smoke test done yet. The oil I've used seems to be burning quite fast, about 1.5 quarts in 2000 miles. I'll be switching to German Castrol this weekend. I should also add that I only use Shell VPower (93 Octane).
TROUBLESHOOTING
BMW's P1092 code is defined as:
Pre-Catalyst Fuel Trim Too Lean Bank 2
This is similar to the generic code of P0174. From OBD-CODES.com, P0174 is typically a vacuum leak after the MAF, a dirty MAF or a clogged fuel filter.
OBD-II Trouble Code: P0174 System Too Lean (Bank 2)
Using my
MAC Tools ET50 code reader, I was able to capture the freeze frame data, just today after clearing the codes last night. I have cleared it again and I'm certain it will come on again, so I will do the freeze frame again to determine if the values and conditions are similar.
This is where I really need your help, especially the techs. I have no clue how to diagnose this using this information but I figure someone out there might be able to help with this information.
Calculated Load : 47.84%
Coolant Temp : 87.0 C [188.6 F]
Engine Speed : 2285 RPM
Vehicle Speed : 59.00 kmh [36.7 mph]
Ignition Timing : 26.00 BDTC
Intake Air Temp : 30.0 C [86.0 F]
Mass Air Flow : 34.69 g/s
Throttle Position : 18.82%
Short term fuel trim Bank 1: 4.67%
Short term fuel trim Bank 2: 3.89%
Long term fuel trim Bank 1: -3.91%
Long term fuel trim Bank 2: -3.91%
At the time I recall the light coming on, I was slowing down to approach a traffic light. The outside air temperature as reported by the dash/cluster was 23.0 C [73.4 F]. Fuel mileage is a steady 18.0 MPG combined as confirmed by the dash/instrument cluster and the last fill up calculation. Range upon a fill up today showed 484 miles. Only noticeable driveability has been due to the oil burning and engine doesn't feel as smooth.
To add insult to injury - this is the strangest part of all. A coworker of mine that I typically go to lunch with every now and again, will get in the car, we'll drive over to wherever, come out and the light goes off. Meanwhile, it's been on for days. This has happened 3 times now. I know it's ridiculous but it was significant enough to mention it. I have NO IDEA what this has to do with it. And then on my way home, the light comes back on again. Go figure!
