Loss of power under load...
 

Hey guys first off let me say hi, and thanks to all the members on here for all the great information you guys post! I've actually solved all problems so far just by reading here even when shops were stumped..(ended up being vanos seals).

So quick info about the car and the issue:
Car is a 2002 x5 3.0i automatic. 200k miles. Got it recently, on the way home I got a CEL, and noticed significant power loss, misfires, no stalling. Noticed that it would barely go uphill and the more you gave it gas the less power it seemed to had. So I got home, and did the basic maintanance, replaced air filter, oil filter, oil, spark plugs(ngk), coolant. It ran a little better, but still had slight misfires sometimes, CEL, ran fine in the city, but any hard accelaration would make the car fall flat on its face, and heavy misfire. Did some research, checked the DISA valve, it was broke so I replaced that. Also cleaned ICV, and replaced the CCV. Car was completely different, felt more responsive, more power, still had CEL, still had slight misfires sometimes, agravated by heavy throttle, and still no power under load. Put it on a tester all it said was random cylinder misfires, sometimes cyl 1, sometime 3, etc.. so as a last resort, I kept seeing about the vanos seals, and saw that it could make you have all my symptoms, so I figured heck surely no one replaced them and at this mileage they're toast, so I replaced those as well and NOW.. car runs smooth, no misfire, no CEL, it feels like it should...UNTIL you press the gas about halfway or more... then again you feel the extreme power loss... motor revs but it doesn't pull... if you feather the gas it feels so good, responsive.. and feels like it has power, but if you wanted to pass somebody you would have a hard time.. also going uphill is also a hard time for this X... any ideas what this could be? It's driving me crazy that I've solved everything and it runs smooth, and no CEL, but it has no real power :(

Thanks in advance for any suggestions !

Also going up hill the car has a hard time revving up and pulling, its not revving up like crazy and the car not going anywhere so trans is not slipping

If you have a misfire have you checked the condition of the coils and then the injectors?

After replacing the vanos seals all misfires went away, under load and normal driving... as far as I got into checking the coils was unplugging each one and listening for a difference witch there was significantly for each one when unplugged.. so I figure they are ok..

So quick recap, replaced spark plugs, air filter, vanos seals, ccv, disa valve, car runs great under normal conditions, no misfires, no CEL's. Under heavy load..ex: uphill or accelarating hard the car just has no steam, feels like its being held back...

Btw guys would a video help?

The coil still can be defective especially becomes intermittent under a load. With the miles on the vehicle you may want to recheck the coils. I have seen two cases where the coil only fails under load and is intermittent. You may also have a bad injector. You need a proper diagnosis.

So time to go to the dealer I guess... something I wanted to avoid since I've had bad experience with them. Went with a 325ci, with ssg trans, with a defective slave cylinder for the clutch and they tried to tell me it was the whole gearbox :))

Sounds like a bad MAF. Suggest you try cleaning it with MAF cleaner. Doesn't always work and even if it does it is time to replace it.

Sounds more like bad fuel pressure under heavy load. Check the fuel pressure at the rail under heavy acceleration

Already tried cleaning it, no change. Tried driving a little without it.. its no better no worse.