Mini Cooper Un-Metered air
This code will set after a few moments of idle after reaching operating temperature. Original problem was the car had visible smoke, performed valve job (valve seals and guides) with new timing chain and guides. and this code came after those repairs - we have:
- Pressurized the boost side of the turbo, no leaks,
- Resealed the intake, the injectors, cleaned throttle body, replaced mass air sensor twice. Replaced Vanos actuator and the solenoid. both O2 sensors replaced. Replaced valve cover, crankcase pressure is at 16hg (39mlb) we scoped the cam to crank timing (running and cranking) and compared to known good waveform, (cranking is OK, at idle actuator is not adjusting. We can command actuation via laptop (BMW ISTA) and scope patter will change.
- Oil Pressure 1.5 bar at idle, 4 bar 3000 RPM. We found the oil pickup wild debris from prior timing chain rails, and clean it
- Compression 150-160 all cylinders
If you are inclined to speak to my shop foremen Patrick, he can be reached at …
Smoke test the intake system also while confirming a closing purge valve. Also the pcv system is known for having issues, causing excessive crankcase vacuum that can be confirmed by pulling the oil cap and checking that it doesn't get aggressively held down(even though procedure says to check with a drilled oil cap and measuring against millibar specs, for your engine 22 millibar is the specs). A smoke test would never detect that.
Forgot, we did a purge valve and we have smoked tested, sprayed cleaner and even used propane -there are no leaks
22 millibar is your specs for crankcase vacuum, you mention having 39 millibar
Frank. If I remember correctly, the purge solenoid and wastegate solenoids both have the same connector. During reassembly, the connectors can get switched (happened to me a few years ago). I would check that possibility first. One of my co-workers by the name of Drew, also brought up the possibility of the cam timing being off due to slight variations in "inexpensive" BMW/Mini timing chain tools. Just a few areas to double check. Good luck.
Check your Vanos solenoids for blocked screens and try an adaption on the solenoid.
What are you're fuel trims doing when code sets?
Spoke with Patrick, advised tech to perform a" running compression" test. This is to determine if he has broken or weak valve spring.
Revisit the cylinder leak down test. His initial results show 10-15% leakage. Mini Cooper allowable is only 8% (warranty guideline for engine replacement).
Test if the engine is suffering from a cylinder taper condition. In other words is the cylinder(s) leaking more air at the bottom of the stroke than at the top of the stroke. (common issue with much "younger" engines . This engine has 133,000 miles on it).
Air flow meter readings are a bit low (tech has swapped out the MAF three different times , once with a known good part). The theory here is that if the engine is suffering from slight cylinder leakage, than the air flow would naturally be low.
Last but not least, it IS possible the DME is in need of replacement. It has been updated using ISTA and still does not resolve the internal air leak issue. (last thing I would try after all mechanical issues have been resolved).
Looks like you are on the right track, we performed several compression tests dry and wet, and finally got down to 8% leak down, we suspect stuck/dirty rings that may have gone undetected with the valve seals allowing the extra oil in the cylinders
I will update later today
Thanks Tom, The cylinder leakage was too high, once it was down to below 8% the code no longer set
I would measure crank case vacuum first, PCV is built into the valve cover. On this vehicle there should be a hose from the valve cover that goes to the intake tube. There is a metering valve between the hose and the snorkel. Remove the hoses and inspect the valve for damage. if the original complaint was smoking it could possibly have been a combined issue.
I agree wholeheartedly. While valve stem seals are common, failed valve covers are more so. Good chance this thing had a bad valve cover the whole time.
It sounds like your timing maybe a little off or the throttle body is defective usually its the timing is slightly off
(16 Hg crankcase pressure) PLEASE Confirm crank case pressure first and foremost. If -16 Hg (inch of mercury) that is way too much negative pressure. Using ISTA have the adaption values been reset? Can you please provide fuel trim data, W/ engine rpm, ect, and maf possibly from a OBD2 scan tool so we could see it graphed?
When you say crankcase pressure is 16hg do you mean 16hg of vacuum?
16hg of vacuum is almost -7 psi. I would say that is WAY too much vacuum.
Remove the oil cap and put your hand over the hole. If there is -7 psi there, it should be trying to suck your hand into the hole.
This is a high vacuum crankcase system
Ok, I'm unfamiliar with that system as I rarely work on BMW's. I'm very curious to hear what the problem is.
Frank I disagree , I have known good specs (in my service bay) N12 engine crankcase pressure at 12 inH20 . attached is a supporting document from MINI with crankcase pressure specs.
I can not print this, I will download and report back to you Thanks.
First, thank you everyone that offered help, looks like the leak down rate was the problem.
after disconnecting high pressure injector relay and performing multiple compression tests on all cylinders we were able to get cylinder leak down results to below 8% - no longer setting the un-metered air code. Justin at LMV Bavarian also led us in this direction, he had several cars with the same code in for tech support. I will reach out to Scott for direction on the bounty
I guess it depends on what a person thinks high vacuum is. The spec of 22mBar is not high vacuum. I'm gonna guess that in your original post where you stated "16hg" that you must have meant 16mmHg, because that converts to 21mBar which is right where it should be.
Tom Morgan pointed out the cylinder leakage was too high, spec to engine is 8% leakage - above that the computer will trigger this code as an internal engine problem. We suspect the oil that was entering the cylinders from the worn valve seals and guides was "improving" overall compression enough for us not to have this code prior to the timing chain and cylinder head repair.
We disabled the high pressure fuel injector circuit to prevent fuel entering the cylinders and ran several more compression and leak tests until we got to less that 8% leak down. Scott did let me know there will be a method to mark as fixed coming up. the bounty will go to Tom Morgan and he will tip others that helped. This was a tremendous help for us, thank you