2012 Mini Cooper S R56 Check Engine P0172

jordanr

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#1
Make
Mini Cooper
Model
S
Year
2012
Miles
?
Engine
R56
Hello everyone,

I have a 2012 Mini Cooper S R56 that currently has the check engine light on with code P0172 (showing as permanent). So far I have had the high pressure fuel pump replaced, the air intake box, the thermostat/thermostat housing, valve cover gasket (due to leakage during a smoke test), all 4 spark plugs, and both O2 sensors. I have cleaned the MAF with CRC MAF cleaner as well. Even with all of this I have had the light continuously come back on even after clearing all codes. The other codes that tend to pop up along with the P0172 are P0300 (random misfires detected, and those have been on cylinders 1,3 and 4). I had a mechanic look at the cylinders and he said they look good. Also I am not noticing any drastic fuel consumption issues as I can fill up and not have to do so again for 2 weeks (average 26.8 miles a gallon). I have noticed over time black soot on my exhaust as this problem has been going on for the last 6 months. The only things I have left to try are checking all the hoses for a vacuum leak, and possibly replacing the MAF and or cylinders. I am just looking for some advice regarding this issue.

Reposted from: https://www.troublecodes.net/pcodes/p0172/#comment-15616
 

billr

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#2
I see lots of parts thrown at this, using live-data might have avoided that. I'm wondering about ECT (especially), IAT, and MAP (if it has that). I gotta say, 26.8 mpg sounds rather poor to me, indicating that it really is running rich.
 
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#3
The only parts I purchased were the spark plugs and the O2 sensors. All that other stuff was replaced by the shady used car lot i got the car from amd the mini dealer. I am new to all this but what are ECT, IAT and MAP?
 
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#4
The only parts I purchased were the spark plugs and the O2 sensors. All that other stuff was replaced by the shady used car lot i got the car from amd the mini dealer. I am new to all this but what are ECT, IAT and MAP?
I know my mini has a Mass Air Flow Sensor
 

billr

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#5
ECT = Engine Coolant Temperature
IAT = Intake Air Temperature (also called MAT, Manifold Air Temperature)
MAP= Manifold Absolute Pressure

Seriously consider getting live-data, it will help a lot. The ELM327 type devices that can do that are quite inexpensive.
 

nickb2

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#6
Back to original problem. I bet 20$ and a beer on a PCV diaphragm. VERY, VERY common. Videos every where. I could make my own, this is a plague for these beemer engines, audis and VW also.
 
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nickb2

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#7
You may even notice a huge amount of vac being pulled from the dip stick tube. Also, that is where the soot is coming from. I would check oil often if you don't resolve this soon.
 
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#9
ECT = Engine Coolant Temperature
IAT = Intake Air Temperature (also called MAT, Manifold Air Temperature)
MAP= Manifold Absolute Pressure

Seriously consider getting live-data, it will help a lot. The ELM327 type devices that can do that are quite inexpensive.

So i took those readings and here they are;
Engine coolant temp 82 degrees at idle
Intake air temp 41 degrees (same as outside air)
Manifold absolute pressure 14.1 psi
Air fuel ratio 14.67
Long term fuel trim -20
Short term -2

Still showing P0172 and random misfires on cylinders 1,2,4
 

billr

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#10
I gotta ask... are those temperatures degrees F or C? (I'm thinking F)

You need to look at coolant temp after the engine has cooled down and stabilized at ambient. At that point ECT, IAT, and ambient should all be nearly the same. Then, get the engine fully warmed-up and read ECT; it should be 180-210F. If it will only get up to 82F, check with an immersion thermometer (meat/candy/cooking) in the coolant. We would need to figure out if the sensor is bad, or the thermostat is bad.
 

grcauto

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#11
Even if the thermostat were bad it wouldn't be correcting for full rich. It almost would have to be the sensor.
14.1 psi is almost no vacuum. Is all your readings at idle? I don't think i need to ask that but I did.
 

billr

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#13
That MAP (14.1 psi) at idle is so poor that it is hardly believable. Can you post a picture of what you are actually seeing on the scanner? I'm guessing that the enormous PCV diaphragm that nickb2 mentioned is leaking, and that the MAP is sensed in the same passageway; so the MAP reading isn't really the pressure in the manifold. Has that diaphragm been checked yet? Do you have a mechanical vacuum gauge that could be teed-in to the brake booster vacuum line, to confirm what the idle MAP is?
 
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#14
In response to the above i am unable to test that. I am going to just have to take it in and have the dealership do what needs to be done when i have the money later this month. I did note MAF voltage at idle was 3V and while cruising 20V. I appreciate your help and insight, thank you again