ok, so here are the problems: 2008 R56 manual transmission
P1497 code (downstream throttle air leak)
surging/power loss between 3k-4.5k rpm
more metallic sound above 4.5k rpm
101k miles

mods:
Alta Intake/turbo inlet alta intercooler and hoses, alta cat-back exhaust there was no major carbon build up at the inspection at 90k

here is the story... CEL comes on right after major loss of horsepower above 3k rpm.
took it to an independent shop who supposedly did a smoke test and found the valve cover needed replacement. CEL remained and no improvement in drivability.

i took it to Northwest Mini who discovered a leak where the turbo inlet meets the turbo ... via smoke test. (why didn't the independent shop find that leak?)

so i replaced the seals on the turbo inlet from Alta. car runs great except between 3-4.5k rpm where it feels like there's no horsepower. the CEL comes and goes.
is it possible the HPFP is going out?

i am running out of ideas . any help would be hugely appreciated!

 

HPFP failure typically manifests at idle first or low rpm. Check the fuel tank vent valve under the manifold. If it fails and sticks open you loose boost pressure under load and it sucks in unmetered air when idling or driving normally. Won't show up on a smoke test unless they open the gas cap.

 

i'll check it, but i don't see how that would let unmetered air in between the MAF sensor and the turbo as it doest connect.

 

The code says, "Downstream throttle air leak". Downstream I believe would be after the throttle body by the intake manifold, really close to where Tigger was talking about.

 

I'd try a carbon clean. I've got 110k+ and it was pretty bad. Perhaps this is messing with your intake air and throwing the code. Also would account for the loss of power.

Theres a DIY on here. I did mine myself, pretty easy and cheap.

 

Item 1 in this picture is the fuel tank breather valve. It connects to your intake manifold. Item 5 is the vent line that runs back to your fuel tank. Fuel fumes do not vent to atmosphere thru the gas cap for emissions reasons. Fuel fumes are pulled into the intake and burned during normal operation. When electrical signals are sent to the pressure converter valve to apply vacuum to the turbos wastegate actuator a separate signal is sent to the fuel tank breather valve to close so that boost pressure is not lost into the gas tank. If this is the problem its a very easy fix.

 

wow, i had no idea. thanks guys! i wasn't able to check it out yesterday due to weather. hopefully today will be sunny when i get off work. thanks again for your help!

 

Been experiencing the same crappy idle/low rpm/hesitation issue and CEL as original post from Carbonfire after doing a boost leak test.


I pressurized entire system to around 3-5 psi from turbo inlet hose after MAF to turbo itself. Heard a 'hissing' sound from that same valve cover PCV hose to vacuum pump . . . only to find upon removal an obvious crack in plastic (not the end connections, the hose itself).


Replaced it, and now have this 'tank vent valve' code. What is this easy fix you mentioned Tigger2011 ?

 

Replacing the valve. Part costs about $80. Electrically operate solenoid valve so when it fails it's done.

 

Look at the PCV hose on the left side of the engine. Those things are cheap thin plastic and have a tendency to fail when the car is older.

 

Yep,I have found a few of the valves, which are mechanically broken but electrically ok.For this reason no fault codes.

 

Did you solve this issue? I’m currently experiencing the EXACT same problem with P1497 (downstream air leak). I tried clearing the codes and drove on the highway, car is completely fine but until I came to a stop light, 45secs to 1min idle, the code came back on. My car is a 2011 Mini Cooper JCW (N14 Engine)

 

Your problem lies in your timing chain and guides. What is happening is that your chain has worn out beyond its service life and is causing your cam timing to change once it comes down to an idle. Replace your timing chain and guides and your problem will be solved. If your guides are missing or broken, you will have to remove the oil pan and check the oil pump screen for guide debris and remove all the debris. Your looking at a timing chain kit and an oil pan gasket. You will also need a cam alignment set for this repair.