Variable Displacement Oil Pump Pressure loss
2013 Mini Cooper N/A R56. N16B16A
Customer complaint of oil light on at idle. Customer immediately shut the car off, and called a tow truck.
Before taking the car in I questioned the service manager at the shop the car was towed in to. They performed an oil change and also replaced the oil pressure switch. While they had the switch out they checked the oil pressure with a manual gauge. This was done with the oil pressure switch removed, The minimum spec listed for oil pressure at idle is 10PSI. This car was running at the low end (hot idle) at about 11-12psi. An off brand filter that was originally installed was exchanged for an OE Mini oil filter from the local dealer. Kendall GT-1 Full Syn oil was used.
Upon receiving the car, I did a quick visual inspection. I could see that the oil pressure switch had been replaced. I then checked the oil level, the oil level was correct. At this point I scanned the vehicle for codes, there were a number of codes stored in the DME, only 2 were active at this time. 2F53- oil control; Static. And within a minute of the car idling, 2F5F-oil pump; mechanical. The oil light would also come on, but would go off when you raised the idle to 2k rpm. Using the Autel Elite/Snap on Modis ultra I was not able to gather much information on what the DME suspected the oil pressure was. There was no data in the scan tool to show me what the computer was seeing for oil pressure. So, I decided to test the voltage return out of the oil pressure switch and at the DME connector. Both matched at about 1.5 volts. This did however indicate low oil pressure, which was accurate. I decided to hook up to the car with ISTA-D to see if I could gather any more info. To my surprise I had just as much data/info as I did with my autel elite.
At this time the fault test plans were very vague, and the first step of the 2F5F code was to check oil level, and the next step was to replace the solenoid. If that did not work, replace the oil pump.
This vehicle has a variable displacement oil pump that will reduce the oil pressure when the solenoid is commanded on.
The oil control solenoid is mounted in the oil pump assembly. The oil pan has to be removed to access the solenoid. The solenoid is serviced separately from the oil pump. The cost difference is severe, so I wanted to make the correct call on which component was failing. I read in the service manual, that with the solenoid unplugged, the oil pressure should be at max. So I hooked my manual gauge to the oil pressure switch port, and took a reading at idle, 11-12 psi as previously tested (I wanted to see with my own eyes.) 2k RPM 15-17psi; 4K RPM 30-35PSI. After taking these readings I decided to take the same readings with the solenoid unplugged. The readings were the same, the pump is not capable of making the correct oil pressure. I wanted to condemn the pump, however I wasnt happy with that. Some thoughts came to mind, I cannot see in my capture that the solenoid is mechanically moving, I did not see anything in the waveform (pintle hump) etc to prove this. Also, when I remove the oil pressure switch it seems like, even though it is plugged in. It is not reading oil pressure so the computer does not seem to send out the command. This is where it would have been helpful to have a “T” to be able to view oil pressure and screw in the oil pressure switch. At this point I connected my power probe to the oil control solenoid, and used both my manual pressure gauge and the WPS to view oil pressure as I manually applied power to the solenoid. Both gauges did not fluctuate in the least. And if the solenoid was “doing work” the WPS would have picked that variation up. Because nothing happened, I wanted to go after the solenoid first.
I was able to sell some time to remove the oil pan and see what we had going on. Upon removing the solenoid and bench testing it, the solenoid was not working as expected. In fact it seemed that the solenoid was very weak, it was moving very slowly. I had to look very closely at the solenoid to see it moving, but it was not snapping back. My immediate thought was that the solenoid was bypassing oil pressure (because it is normally closed at rest) The dealership had a oil control solenoid right on the shelf. I brought it back to the shop and bench tested it. A loud audible click was heard and the solenoid snapped closed afterwards.
Now it was time to re-test. The oil control solenoid was reinstalled, at this point while the RTV sealant was drying. I decided to hook my power probe up to the solenoid wiring and listen for a click. It was hard for me to hear the solenoid moving once it was installed in the oil pump. However I used a stethoscope pressed against the oil pan and could hear the click plain as day (I tried this with the old solenoid and I was not able to hear the solenoid click)
Now that the new solenoid was installed I re-tested with the WPS and the oil pressure was up where it was supposed to be. Control was there, and the codes were gone. I did the same testing with the power probe (Commanding the ocs) to show what it looked like with the WPS tapped in on another channel.
The capture that was originally taken, cold startup WPS jump to 75psi, that immediately plummeted to 10psi indicated to me that the oil pump was (possibly) capable of making this kind of oil pressure. Because this system seems to be hard to obtain information on, I wanted to do what I could to obtain some known good captures, and operation.
I wanted to make note this vehicle was Diagnosed by a friend of mine Michael Broccolo. ( I had that in the beginning of the the post but it was lost somehow during the editing process. Can we add editing to posts soon web developer? )
This vehicles issue was brought up in our networking group chat and as a team, we all helped to diagnose the vehicle. I thought this was a very interesting case study and asked Michael to write up a case study to publish. This is yet another example of how the power of networking can result in great things.
We hear you loud and clear. The editing project is underway so editing will be available very soon. Thanks for your patience.
Brian thank you for your help on this one and for posting it for me.
What I like aboutvthis one particularly is: your lack of availabile info, regarding system functionality was made up for by your knowledge of how each component works.
Your common-sense approach , great/capable tools and lots of PRACTICE yielded you the answer and reason to repla the faulty solenoid. I like how this all camec together. Thanks for the follow-up captures that proved your hypothesis 👍
Thanks Brandon. I cannot take credit though however, Mr. Broccolo was the guy doing the work on this one. We just helped him narrow it down and I asked him to write this post. He does not yet have an account here.
I just signed up Brandon. Happy to be here, a lot of good info to catch up on!!
Brian thanks for sharing your findings. Every time i see a BMW/Mini post on here or other forums i really start to miss working on these vehicles. Also how do you like that Fluke 233a? going back n forth on the 88v or 233a.
I honestly believe that testing variable oil pumps with a pressure is the only way to get it done. I think hooking up a transducer and activating with a power probe will tell me much more about the operation of this system then any written material. Thanks guys for putting this out there.
Thanks Chris Martino for letting me include you on this one as well.
Nice work guys. And to measure it with a scope and transducer is going to be the only way to really see what is happening to these things. Watching a mechanical gauge may have missed the spike in pressure, or you could just think it was nothing. But the kicker was the no pintle hump showing the solenoid operating. I can't wait to get a chance to check this out on my own!