2012 Mini Cooper Base Error Code 2789 Fuel Mixture Adaptation but running well

I finally got my cooper running after 2 years (non-turbo N-16 engine). Before it sat for years it was barely drivable, and one of the things i fixed now was the valve cover gasket because oil filled the spark plug coil wells. I also changed the plugs, coil, fuel filter and pump, and air filter. I was getting a mass air sensor plausability error and then cleaned the mass air sensor and throttle body and cleared codes. That code did not come back but I am now getting a new code 2789 Fuel Mixture Adaptation, idling per time unit. My Foxwell scan tool has the ability to delete adaptations, but I would like to check with someone who understands this before I do as I saw some posts about people getting issues after resetting adaptations. I just want to make sure that is the right thing to do. It drives ok, and I scanned for misfires and do not have any. I ran some live data while the engine was running and warm as shown in the attached photos, but I don't have enough knowledge to know if the data is good or bad and if I should reset adaptations. Any advice would be greatly appreciation. Thanks.

First of all I want to say welcome aboard here on the ScannerDanner.com forums. This is a great group of people here in the forums during the last 5-7 years with and without the growth/ I'm sure it'll continue to be a great place to come get some good information, help. chat, etc.

Taking a rough shot in the dark I was able to come up with this regarding the code & description




"P2789 - Clutch "A" Adaptive Learning at Limit

Description :
The clutch actuation circuit is closely monitored for temperature and pressure variations. A fault code is stored if such a condition occurs. Temperature and pressure anomalies can cause damage to system components so a vehicle may enter limited operating strategy (limp mode) if this code is stored. The clutch actuator is also monitored for excessive wear, so a calibration must be carried out anytime there is a repair to the vehicle. This is carried out using a diagnostic tool.

Possible Causes could be :
Component
or
Mechanical Defect"


Given that description I did notice a few descriptors missing for vehicle information that you posted that could be a little more helpful in some instances. What trim level is this vehicle, is it a coupe, sedan, convertible. Automatic or manual transmission? Also being that this vehicle sat for two years have you went through and checked out all of the fluid levels with the vehicle cold and also once the vehicle has warmed up? Keep in mind with fluid levels that even though they may have been good before the vehicle sat overtime fluids tend to attract moisture.

Note, This post was done using voice to text speech recognition. I apologize ahead of time for any grammar errors or omissions.
If you have any other questions please feel free to ask as there are many others here who will most likely chime in as well. Before I forget about it have a happy holidays when you get around to it as well and don't eat too many cookies that are meant for Santa. Ha Ha.....

Thank you for your reply and happy holidays to you as well. I should clarify that the code 2789 is the BMW/ Mini specific code that my scanner gives. According to my Bentley manual (see attached picture) it equates to a P2187 system too lean at idle (Bank 1). This is a manual transmission 2012 Mini Cooper hatch. I also replaced the fuel, radiator and antifreeze and oil and filter. It runs a little rough at cold idle but with each start that has been getting better. It runs and drives fine and not misfires. I am wondering of this high fuel adaptation is stirred from when the car had issues a few years ago and was misfiring and barely drivable. Thanks for your advice and have a great holiday!

To answer your question, I don't see a problem with resetting the adaptations? Worst case, the adaptations come back to where they are and you get a code again. :silly:

For a lean idle fault, I'd first suggest checking crankcase pressure with a manometer in the dipstick port. They're too cheap to not have one.

www.amazon.com/Manometer-RISEPRO-Digital...ential/dp/B01680C4C2

www.amazon.com/Mityvac-MVA6912-Diagnosti...er-Kit/dp/B007TMSN5G

Specification is 36 mbar +/- 4 mbar. That translates to around 14 inH20, or 1 inHg.

Thanks. What will this pressure tell me?

SamM wrote:

Thanks. What will this pressure tell me?

If the vacuum is significantly higher than spec, it's a smoking gun for a failed valve cover. I've heard of people taking them apart and replacing the diaphragm/membrane inside that makes the magic happen? Never done it myself, but it's an option.

If the vacuum is in spec or low, then that means the diaphragm/membrane is likely fine, and you're looking for vacuum leaks/unmetered air. That includes things like oil fill caps, dipstick seals and pinched valve cover gaskets. Those aren't the only ways to get unmetered air, just the most common ones I've seen.

Thanks. I just replaced the valve cover gasket and the pvc membrane on the cover so hopefully I did it right. Appreciate the advice.

SamM wrote:

Thanks. I just replaced the valve cover gasket and the pvc membrane on the cover so hopefully I did it right. Appreciate the advice.

No worries. I'm sorry if I sound like I'm doubting your repair or workmanship. :blush: Genuinely not.

No I am doubting my own work. First time doing work like this n a car and glad I was actually able to get it running. So far I have changed the battery, the radiator, oil, spark plugs, ignition coils, antifreeze, valve cover gasket, pcv valve, hood latches, hood release cable, fuel pump,, fuel filter assembly, and replaced gasoline. A learning experience. 40 years ago, I wish I went to auto mechanic school rather than college. Thanks again for your input.

After resetting fuel adaptations in was surging on idle for a while. As it warmed up it ran better. Shut down clear codes and restarted and went for 10 mile drive in highway and local roads. No codes yet but not all obd codes are ready. Going down hill of the throttle O2 voltage precast was over 2 but dropped to 1.4 when on throttle. Fuel adaptations are now between 4 and 5 instead of close to 8. I took some pictures of my scanner but do r know if this data means anything. It has intake manifold pressure but not crankcase pressure. Any thoughts or is this useless data. Need a launch or autel scanner but not sure what to buy. Thanks.

Here are scans.

Actually, that data isn't terrible? This engine doesn't have a crankcase pressure sensor, so you're not missing anything. :silly:

The airflow rate *could* be indicative of an issue? The general rule-of-thumb is that the MAF should read the same in grams/second as the displacement of the engine in liters. So, if you had a 3.0L engine, your MAF should indicate 3.0 g/s at hot idle with no loads on.

I put your 3.8 kg/h reading into a converter and got around 1 g/s. Technically, that's low, and suggests unmetered air. That'd agree with the 2789 code you retrieved earlier. BUT, things also get more complicated with this engine due to it's low displacement and variable valve lift system.

If you're intent on getting another scanner, I'd suggest going with Autel. I own one of both, but still find myself reaching for the Autel more.

Thanks and happy holidays! I order a smoke tester to check for vacuum leaks and also ordered what you suggested to check crankcase pressure. Appreciate the input. I got impulsive yesterday and ordered the Launch X431 v.4.0 Pro as it seemed to have more coding for european cars. Hopefully not a mistake. Also, my Mini 2B5C Air Mass Sensor, plausibility code came back.

Tyler wrote:

I put your 3.8 kg/h reading into a converter and got around 1 g/s.

Quick tip: divide the kg/h by 3.6 to get your g/sec without calculator ( or, - roughly - ÷7*2).

You will see your scan data refers to an adaptive correction and another one called multiplicative, in your case the latter one being lower. German cars use these terms to distinguish between idling/low rpm and off idling condition. Adaptive correction describes idle/low load( below 1200rpm/ at least on VAG products, BMW/MINI might be≤1000rpm,not sure) where as multiplicative reflects higher rpm/loads. The scan data shows more ft correction at idle, supporting the idea of possibly unmetered air as Tyler already mentioned.

In combination with the input from other sensors like ckp, tps and like ones the control unit looks for to be expected values for the maf reading as well. The plausibility code will be flagged when the comparative data doesn't jive. In your case it could be a vacuum leak but there are more possibilities like an out of calibration mat sensor. The smoke machine will take a good step ahead n your diagnostic journey.

Just in case you haven't already explained somewhere else: I still would like to know what finally made the engine start after the initial problems you described in the other thread.

Thanks. I wish I had more diagnostic knowledge but this forum is very helpful. I ended up getting my car running by replacing the fuel filter assembly which contains the fuel pressure regulator and hoses to fuel pump. Don’t know if spraying starter fluid in my earlier tests could have negatively affected the throttle body. So many sensors but will see if the smoke test yields anything and then go from there. Appreciate the help.

Quick question. Should I put the smoke in the tube before the air filter and mass airflow sensor or after those going into the intake? Thanks.

Connect the machine between the throttle body and the MAF sensor for a first test.. Do a second leak test connecting directly to the intake manifold. Keep the throttle body/butterfly valve closed during each test.

Still waiting on my smoke machine but can you confirm that these short and long term fuel trims are inductive of a vacuum leak? This is what I gather from some of the scanner Danner videos I watched but I know there is much more to this. Fuel trims are very high on idle and go down as engine speed increases as shown on the attached video. When I am cruising on the highway it drives great and both long and short term fuel trims hover positive and negative right around zero.

SamM wrote:

Thanks. I wish I had more diagnostic knowledge but this forum is very helpful. I ended up getting my car running by replacing the fuel filter assembly which contains the fuel pressure regulator and hoses to fuel pump. Don’t know if spraying starter fluid in my earlier tests could have negatively affected the throttle body. So many sensors but will see if the smoke test yields anything and then go from there. Appreciate the help.

Don't sweat the knowledge part as it comes with time and we're all still learning all the time. If I tell you I don't learn something every day then I'd probably be lying. One of the others posting in this thread has the signature that sums it up as well. Can't recall it off the top of my head but it can't be missed

It turned out my problem was the valve cover with the built in PCV valve. Replaced the cover and reset adaptions and fuel trims are near zero and no pending codes. Thanks everyone for your input!