I've been getting the P0302 error code every couple of days along with P115C. When it happens the car has much less power, like the turbo isn't working. I assume this is because it's only running on 3 cylinders!
It lasts for a few minutes, then the car recovers and runs OK.
I checked the #2 spark plug, looks fine (they were replaced 6 months ago). It's been raining a lot lately, so I though it might be a moisture issue. I removed the coilpacks and dabbed on a bit of dielectric grease before reattaching (I hadn't done this back when I changed the plugs). Then I went OCD and removed every electrical connector under the hood, dried with a hairdryer and applied dielectric grease before reattaching. The car ran fine for another day, then I got P0302 and p115c again. Each time it is cylinder #2.
Now the p115c is nothing new - I have had that intermittently for over 2 years and the dealer has not been able to find the problem (I actually gave up and just live with it). There were never any symptoms accompanying p115c. The light would come on and go away after a day.
I don't know whether the 2 codes are related or if its just a coincidence they are appearing together now.
Last week my R56 gave me the codes P0300, P0301, P0302, P0304. The car was hesitating and stumbling on acceleration. Talked with my coworkers, we are general aviation aircraft mechanics, decided it might be some bad fuel. Anyway put about 1 cup of 91% isopropyl alcohol in the tank, stumble went away. Cleared the codes, they haven't come back, I'm almost done with the second tank of gas since. Might not help with the P115C code, but if there has been alot of rain, you might have picked up some water in the fuel. The alcohol is cheap, might be worth a try!
Now the p115c is nothing new - I have had that intermittently for over 2 years and the dealer has not been able to find the problem (I actually gave up and just live with it). There were never any symptoms accompanying p115c.
* MINI DTC P115C (0x2775 or 0x2B56 or 0x2B58 or 0x2B5C) - Mass Air Volume Flow 'A' Too Low
The ECU is still seeing too small of inlet volume of air passing the MAF.
Which means there could be an opening / leak after the MAF allowing unmetered air to enter the engine.
It could be:
a.) the MAF is shot (rare, but occurs)
b.) there's a leak in the intake system - a pressure check will confirm that
c.) valve cover leak / crack, which is becoming a more common occurance
d.) or... do you have a catch can installed?
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thanks Joel, I'll try some fuel system treatment to see if that helps. I also swapped the coilpack on cylinder 2 with cylinder 1 to see if the miss-fire changes to cylinder 1.
for the p115c:
The dealer replaced the $600 MAF, but the CEL came back a day later (they refunded me for the part).
They were unable to find any air leaks using a smoke test, but I don't know if they checked the valve cover.
I had a catch can, but removed it a couple years ago. Had the CEL with it and without it.
Checking the valve cover sounds like a good idea, thanks!
Oh, one other thing I forgot. When I replaced the bypass valve last spring with the WMW bybass valve, the p115c code didn't come on for 5 months - usually its a weekly occurrence. I thought for sure that had solved it, but the CEL eventually returned. It seems unlikely that the new bypass valve already has issues though, so I think that was a coincidence. Maybe.
Do you have an after market silicone intake hose(between the air cleaner and the turbo charger)? I had the old Alta silicone hose that started collapsing after about a year and had to replace it with a metal one. Mine was throwing the 115 codes especially after rapid slowing from 30min-1hr sustained high speed.
I had P115C and it was eventually traced to carbon build up on the intake valves. I had it walnut shelled about 12 months earlier and had a catch con on. Another round of blasting solved it. Well, for another 10k miles...
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