N54 135i 6MT Feels Sluggish after HPFP and Alternator Replacement

[danielberman]

Just had the HPFP, fuel sensor, and alternator replaced on my N54 135i. The car idles fine, but feels like it’s down 30-40hp. There’s a whining noise that increases with engine RPM, the new alternator is a remanufactured unit - could this be the source of my horsepower loss?

(Both HPFP, fuel sensor and Alternator were replaced at the same time)

[Converted1]

Did you have a rebuilt or new HPFP put in? I ask because I just went through a saga with 2 faulty rebuilt pumps in a row. They both were from a reputable reseller. I ended up getting a brand new oem pump and that one was good. These rebuilt pumps doesn’t even seem to be bench tested.

[danielberman]

Originally Posted by Converted1

Did you have a rebuilt or new HPFP put in? I ask because I just went through a saga with 2 faulty rebuilt pumps in a row. They both were from a reputable reseller. I ended up getting a brand new oem pump and that one was good. These rebuilt pumps doesn’t even seem to be bench tested.

Dealer replaced the pump

[Converted1]

Originally Posted by danielberman

Dealer replaced the pump

Don’t rule out the pump. I’ve heard that even oem ones are having problems out of the box.

[jwolf]

You would get a code if it was bad enough to feel. Failing HPFP causes a cascade of codes when the engine does not get enough fuel. Usually sustained wide open pull like a 1-3 gears to redline will tell the story.