Just posting this in here for the record - Check out my actual thread for updates
http://www.xbimmers.com/forums/showthread.php?t=1321492
I was on a trip to NC from Pittsburgh 2 weeks ago. On the way back from Charlotte roughly in Virginia, I received a Engine Malfunction - Reduced Power message on my dash. We were roughly 360ish miles from home on a Sunday with my wife and 10 month old son.
We stopped a few times in hopes that on a restart the light would go away. Of course it didn't. So we ended up limping home all the way.
We take the car to the dealership and at first they reprogrammed the ECU and all the modules in the car to the latest DME software. ( I personally didn't think this would solve this issue) But I went along with it. The dealership test drove the X5 and called me and said it was fixed!
I pick up the vehicle, pay the $255 for the program and start driving home. As soon as I get on the on-ramp to the highway... guess what - Engine Malfunction - Reduced Power. So i drive it right back to BMW and jump right back in the same loaner!
It takes a few days at BMW to run through their test plan and they notice that -
CLIENT STATES CHECK ENGINE LIGHT IS ON
FAULT FOR BOOST PRESSURE PLAUSIBILITY TOO LOW .
WORKED THROUGH TEST PLAN AND COMPLETED ALL CHECKS
INCLUDING MANUALLY APPLYING VACUUM TO WASTE GATE ACTUATOR
AND FOUND NO CAUSE FOR BOOST PRESSURE ISSUE. CONTINUED
TEST PLAN WITH RUNNING TURBO SELF TEST WHICH ABORTS.
FOUND WHEN ENGINE IS HOT PRESSURE CONVERTER IS
MALFUNCTIONING AND SUPPLYING CORRECT VACUUM TO WASTE GATE
ACTUATOR. ACTUATOR WORKED CORRECTLY WHEN TESTED EARLIER
IN TEST PLAN INDICATING A HEAT SOAK ISSUE WITH COMPONENT.
REPLACED PRESSURE CONVERTER FOR WASTE GATE. CLEARED FAULT
MEMORY AND ROAD TESTED 3 MILES OK. HAD DRIVEN EXTENSIVELY
TO VERIFY REPAIR , NO MALFUNCTION OCCURRED IN OVER 30
MILES.
11-74-7-626-351 PRESSURE CONVERTER (Pneumatic Wastegate Actuator)
So they road-tested the X5 for 30 miles and the light has not come back on.
I pick the car up later today! Lets hope that this fixes the issue!
I figured I'd write this up if anyone has this same issue and wants to replace the part themselves instead of the dealership.