I have a Clubman S (R55) 2008. After an engine check light as a result of a 2876 code (lean mixture) showed up out of the blue, I've had this new issue.

The dealership reset the engine light. All seemed OK for about 150km, then, this new problem. The engine will not boost above 4000 RPM.

There is no engine check light. There is boost at low RPM and then as the RPM increases beyond 3000RPM you can feel and see the boost begins to be throttled back. There are no air leaks, I have checked this. The DV/BOV is also OK, I checked it for tears.

I am at a loss. After doing as much research as I can a faulty PCV seems to be the most sensible thing it can be.

Can anyone offer any advice, have you run across this problem before?

Many thanks.

 

If the PCV valve in the line coming from the valve cover to the intake manifold failed in the open position, you would have very high crankcase pressure. It will relieve some of the pressure though the breather line going to the turbo inlet hose, but you would notice you are burning a lot of oil. To my knowledge the N14 does not have a crankcase pressure sensor. I could be wrong.

Even though you don't have a CEL, you might have a pending code that could point at something else. Have someone at the dealer drive with you and point it out.

 

Thanks Shane. Since the car is out of warranty, 4 1/2years old, 38,000 kms, I'm trying to sort this out without going back to the dealership. Last time it was $200 to reset the code and make a brief visual check.

I've been thinking about the ACCESSport to simply read the codes and reset as needed, and in the longer term enjoy better performance once this current issue is resolved. Torn as to what to do or how best to diagnose this.

BTW, I do feel the car uses much more oil than it should... could have been an early warning of sorts, though apparently according to Mini, the cars do use oil and from what I estimated our car uses it's "normal". I have owned a turbo car before and it never used nearly as much oil. I have had the odd whiff of burning oil in the past month or two but put it down to vehicles around me, maybe it has indeed been our car...

I wonder if there is a simply way to check this PCV, I don't believe there is...

 

The crankcase normally operates at no pressure or less, if the PCV valve were stuck open and the turbocharger were pressurizing the crankcase, you'd be blowing oil out of the seals and the dipstick tube, a real mess!

You could have a torn hose or a bad hose connection on the pressure side of the turbocharger.

Dave

 

Hi Dave, I pressure tested the hot side from the the outlet of the turbo to 15psi, there were no leaks or hisses...

OK, so a faulty PCV would really make a mess, that's not the case, so perhaps it's not that. Could part of it have failed and possibly cause this issue?

 

The visible thing is that the car at low RPM, under 3500 can make 10psi boost, I see it on the boost gauge, but as the RPM rises the boost drops to near zero, so this is not so much a leak as something causing the turbo wastegate to open when it shouldn't, ECU is protecting something yet there is no CEL.

I really don't know much about the ECU, but if there is no engine CEL could there still be a fault condition recorded that is simply causing the ECU to do this?

 

Hmm that is really weird. Is the wastegate arm really loose? I'm honestly just speculating at this point. I really wonder if there is a pending code you can't see...

Did you already check all the little vacuum hoses coming off the vacuum pump? Now that I think of it, that is un-metered air from the vacuum pump lines that the ECU would not notice if there was an issue. However, you would get some kind of "low performance" error if the boost was really out of whack. I've heard of that happening around here before but I can't remember the OBDII code. Next spot to check is the vacuum tank of the back of the motor (firewall side) for any cracks, but man that's such a hard part to look at with the subframe in the way.

Someone with the Bentley manual can hopefully chime in. There has to be some kind of troubleshooting section in that manual. Too bad mine doesn't come till x-mas!

 

Just thinking out loud here.

If the turbo's diverter valve is operated electronically from the Engine Control Unit and voltage opens it, if you unplugged the diverter valve and you then maintained boost, that would tell you that the ECU is causing your engine to loose boost pressure. This wouldn't work, if the diverter valve is kept closed by the presence of voltage from the ECU, then you wouldn't get any boost, if the diverter valve were unplugged.

It would be something to try as a diagnostic, it wouldn't tell you why the ECU was telling the diverter valve to open, you would have to run a diagnostic on the ECU to find out, and that would require a dealer or an independent MINI specialist.

Dave

 

I did today just order the Bentley manual... I hope this helps me make a more informed diagnosis or at least tell me where I could begin looking.

I appreciate your thoughts, I've not had to work on this car since I got it, been fortuate in that regard, but times have changed and the car is our of warranty. I do miss the much simpler turbo car I had before, it had room to work, and was certainly not so complicated or picky... a modified Fiat Uno Turbo that with a 1400cc motor would smoke the Mini up until then end of 4th gear ;-) power to weight was awesome. Anyway...

 

I have similarly issues 08 clubman s, low power, dipstick blowout twice, oil all over. I don't think it's just the cylinder head cover/PVC because of the low power, and the noisy turbo ducts that I know nothing about.

 

OK, thanks Louh56... you're saying too that it is NOT the PCV becuase I don't have oil blowout, correct?

Have you fixed your issues?

I only have ALTA CAI (cold air intake), it has been on since 500kms, now with 38000kms this new issue. Maybe I should remove the ALTA stuff and go back to stock air intake, it just does not make any sense.

If it's not air leaks as I've checked this, what else could it possibly be?

I did another test again, since it's been raining... at 3000RPM I get about 8psi (3rd gear) with my foot flat, by 4000RPM zero boost. The turbo is not spooling up at all.