2011 X5 35i N55 - intermittent starting + CEL on WOT

[bmwannabe]

Originally Posted by SB1120

For wastegate- the vacuum reservoir is built into the valve cover. Test it to see if it holds vacuum. Plug the source (13-14mm barb near front right corner where nylon hose connects). Plug one of the small 6mm barbs. Connect a vac pump/gauge to the other barb, pull a vacuum and see if it holds. If it’s cracked, you’ll have to replace the valve cover.

For the valvetronic code, line disconnection and no start- if the valvetronic shaft is on the “closed” stop, the intake valves are fully closed and the engine will not fire. The servomotor can fail, harness can have poor connection or oil wicking via valvetronic motor connection OR in my case, the DME can fail altogether. My 12 gave no warnings. Just died one day while driving. That was at about 140k in 2017. I replaced the valvetronic motor with the valve cover in 2020 around 183k and that was a huge headache because I had to do the whole job again with a new eccentric shaft, needle bearings and bearing shells. The original shaft, bearings and servomotor wear together. Once disturbed to install the motor, the old shaft was slightly binding and the motor control is very sensitive. It felt totally fine to me, manually moving the shaft but to the motor and controller something was wrong. ~1500 later and a couple lost weekends, my x5 was back to life. Sharing just to warn you, if you have this repair completed in the future, plan for all of the above and it’s recommended to do the harness at the same time. $$$!

Thanks for the detailed write up especially about the VVT. Mechanic mentioned the shaft and motor need replacing together and it’s a painful and expensive process. I’ll share a link to what it sounds Like when it doesn’t want to start. Oddly enough. Leave it for 10 mins and it will start up with no codes. It’s happened over 10 times in the last 2 months and always resolves after retrying 5-10 mins later.

As for the valve cover being cracked. I seriously hope not. It was replaced less than 500Km ago due to incessant whistling noise which is common of vacuume leak.

When it fails to start it almost feels like it’s not getting fuel. But then the HPFP was replaced less than a year ago.

Once I replace the glaring crack in the vacuum line to boost solenoid I’ll test it again to confirm the boost related issues are gone.

Thanks again!