Hey all just trying to get a 2nd opinion here. I own a 08 E63 with 154k on the clock. I recently took it in o have my 02 sensors changed and valve gasket seals replaced. When I got it back I noticed it was idling rough while in park or N.jumps from 800ish to 1k ish with no foot on the brake in P.Mechanic says it's probably the brake booster causing a vacuum leak and if so that's cool I'll work on fixing that but it feels slick it's Abt to cut off it's idling that weirdly ! Any info would be helpful!!

 

probably a vacuum leak somewhere. PCV valve or throttle body plate wouldn't cause high idle, but would cause lean codes at idle.

 

When I bought my 2007 E63 in 2017, high idle is what I experienced straight out of the gate! Besides the fact that the previous owner put 2500 mi on the car in the month it took for his title to clear his bank, there was a huge smiley face gouge on the hood that I had repaired before I took possession, so as I was driving it home from the Body Shop I couldn't help but notice the hotter the engine got, the higher the idle would get! By the time I got home 5 miles later, it was so high that the automatic shifting was impaired significantly! Definitely not what I was expecting!

Bottom line, this all happened way before I even had the thought of buying STAR/DAS, an absolute necessity to do almost anything suspension related, which was what I had planned on tackling as I knew I had a slight pull to the right. So my gut instinct pointed to the Intake, so I removed it and it had it rebuilt by RMT. It was only then that my attention was drawn to the intake runners being caked with Carbon which led me to remove both Heads, had them rebuilt during which I was informed 8 of 16 Intake Valves were apparently bent! I never would have known otherwise! Of course I rebuilt with new everything (Head Bolts, Spark Plugs,Fuel Injectors, Oil Sensors, Crank Sensor, STS Black Valve Tappets, Head and Valve Gaskets, etc.)

Upon putting it all back together, it was then that I had discovered the reason for the bent intake valves had to do with my Camshaft Adjusters on the Passenger side having been installed not only incorrectly but they had both been taken apart, with the one main inner gear installed backwards, which meant that the oil “pin-cylinder” wasn’t facing the Oil Pressure sensor on the front side but facing the backside. What's even more mind blowing is the reason I discovered it upon install, that is, with this inner gear being installed backwards, the race that is supposed to mate with the end of the camshaft now was facing the front! The side now incorrectly facing the rear (ie-camshaft) had a smaller race such that the end of the Camshaft wouldn’t fit, not even close, to mate with that Diamond Washer. This means that whole Cam Adjuster sort of wobbled against the end of the Camshaft and, if not for the Cam Adjuster outer gear being barely supported by the Crank Gear below it, it would have been catastrophic! Moreover, I say “barely” due to that gear not evenly being lined up with the Crank Gear below because of its having been drawn foreword/away from the Camshaft! It was only a result of putting it back on that I noticed this crazy mishap!

Now that it’s all back together, the engine is running great! Was it the Throttle Body Plenum being riddled with holes or the bent intake valves, I’m not entirely sure, but I’m leaning towards the Throttle body in my case!

 

oh wow...that is a horrible story. glad you got that sorted out.