Mixture too lean, P0171, P0174, P0313

[MaddMatt]

Check the vacuum line that runs from the SAP and wraps around the the cylinder head over at the firewall and ends to the right side of the intake manifold. That vacuum line ages overtime and gets brittle and cracks that can cause vacuum leak and throw out the check engine light with those mentioned codes.

If you used an OBD2 scanner to retrieve the codes then can your scanner has the ability to pull freeze frame data? If so, then post them up here. Not too keen on using a used MAF.

I don't have a great scanner, just a fairly cheap one from autozone that can read/clear. "Used" MAF is a Bosch unit that had a claimed 9000 miles on it. Plan to get a SAP vac line today as well as the 7mm plug on the back of the manifold that is all cracked and leaking.

[MaddMatt]

Turned out to be the oil tube o-ring and the MAF causing the problems. SES light free for several months now.

[Roman D]

Hi guys, excellent tread, lots of info. Let me ask you for opinion please. E53 X5 3.0, had codes 071, 074. did a smoke test - found 1 little rubber cap that was cracked - it was capping some nozzle. anyway - had the car scanned again, only 174 is present. Car runs OK but somewhat dull and I can hear hissing sound but can't say if it the way air passing trough intake or abnormal... what do you think?

[Simonc633]

Hi sorry I'm new on here as only just got my 330Ci 2003 model, had it 1 day and the fill coolant light comes on intermittently, a friend said it could be air in the system! But before I could get to check this the Engine Management Light came on today and has stayed on. I have checked withOBD2 Maxiscan and it has come up with 4 fault codes, P1085 P0444 P0171 P0174. I'm not sure if these are all related or even related to the first issue with coolant warning so some advice would be very welcome as having googled the codes it seems a bit hit and miss as it could be faulty or dirty sensors cracked vacuum hoses and all sorts of things I have no idea about. Any advice or even a point in the right directions?

[Doge]

It is most likely a torn intake boot (not for the coolant though).
To inspect simply open the hood (bonnet). The bottom right part of the engine bay houses the air box. The rear of the air box contains the mass air flow sensor, from there are attached two (2) inline rubber boots for the air intake.
They lead from the MAF sensor to the throttle body and the idle air control valve, and are connected by a coupler. Every end in secured by a worm-driven clamp (1/4" hex or a slotted driver).
The first intake boot has a tee-off for the vacuum control and a 90 degree elbow with two lines coming off of it...check the tee-off for cracking, check the 90 degree elbow for the connected lines.
The second intake boot is harder to get at and inspect, but it can be done with a flashlight. The split in the second boot is were mine tore open a gaping hole, it's the split off leading to the IACV (which is on top of the throttle body).

Inspect that entire assembly of parts for cracks, holes or mis/non-connections. You may need to remove the air box and/or the first intake boot to do a proper inspection. If there is a hole or crack, gaffer tape works wonders as a temporary solution. (Mind you, this may not be the issue but it's as good a place as any to start looking and rule out. That rubber doesn't last the lifetime of the car, and needs to be replaced periodically.)
As far as the coolant goes, do a thorough inspection of the coolant lines and the expansion tank, you may need to ramp it in order to see the under bits if nothing else is visible.
Look at WoLF's thread http://www.bimmerforums.com/forum/sh...ed-5-22-2014**
Coolant issues are common in these cars.
If you really can't find the information you need by searching, or are really in a bind, start a new thread and state your exact problem. Be as specific as possible, include pictures or a link to a youtube video.
Hope this helps. Good luck, and welcome to the party.

[Simonc633]

Thanks Doge will have good look and hopefully let you know how I get on, will also look and see how to start a new thread

[tdr1919]

I'm glad it was useful. And the replacement parts are cheap!

This is my problem also, how did you remove that lower boot, what did you have to remove to get at the hose clmp on the throttle body, last question where did you order the part from ?
thanks -tom

[MIKYZZ4]

Study these videos:https://www.youtube.com/results?sear...ci+intake+boot

[Blikk]

I know this isn't the correct forum, but exact same issues, hoping for some insight...

Picked up my first BMW used a couple months back. Within days, the SES light was on. First had Autozone run the codes (and reset, they were back on same day). They were Bank 1 and Bank 2 too lean. Also got P1083 and P1085. Today I rec'd my Peake decoder and my Bentley manuals. The last two codes also point to Fuel Control Limit Too Lean in both banks.

Now, the Peake codes came up with:
--Oxygen sensor control limit, Cyl #1-3
--Oxygen sensor control limit, Cyl #4-6
--Oxygen sensor adaptation limit, Cyl #1-3
--Oxygen sensor adaptation limit, Cyl #4-6
--Misfire detected, cylinder #4
--Misfire detected, cylinder #5

With my windows down, as I am driving thru a parking lot, I do hear a whistle noise. Either it goes away or I can't hear it above 15-20 MPH. I took off my whole intake back to the throttle body and didn't find any leaks. MAF looked OK.

My best guesses, and open to input:
1) did my O2 sensors go bad due to an air leak throwing the fuel mixture off?
2) or, could I have bad coil(s), causing misfire(s) and making the O2 sensors bad?

I am curious about the Crankcase vent valve, haven't checked it yet...does the M54 engine also have this?

It ran much better before the service engine light...it would take off better and had good topend acceleration...still OK, but not like it was...

Figure my next target would be the coils and plugs...

ANY help from the experts is appreciated...thanks in advance!

I purchased a salvaged '01 325i and have chased these same gremlins. My quest lasted 3 years and was both BMW serviced and DIY. I'd changed everything; disa, MAF, spark plugs, rotated coils, crankcase valve (and yes the M54 has one), intake boots, intake manifold gaskets, O2 sensors, throttle position sensors, valve cover gasket, and various vacuum lines. When it lost acceleration, I took it to an independant mechanic who found that my Bank 1 Catalytic Converter was clogged. Not willing to pay the $1,000 estimate, I took the car home and ordered an aftermarket unit through Bavarian Autoworks. Problem solved. If you're still chasing these codes, I recommend you have an independent mechanic test your Catalytic Converter.