Originally Posted by andy92782
Add me to the list...
I actually made this video over a year ago. At the time, my car was running on the original HPFP and injectors but it was on its 2nd set of plugs.
My car is an automatic. When the transmission is in gear, the idle stays low. If I put it in Park (where there's less load on it), then what you see in the video will probably occur. Note: the engine needs to be warmed up for this to happen. I currently have 64K miles.
Also, since I took this video, my car has developed a problem where it will stumble on a cold start after firing up but then immediately run smoothly. This started happening about ~5K miles after the HPFP was replaced under the recall. Note: My car has a 12/06 build date and wasn't eligible for the injector recall. All injectors are original.
For the most part, the car still runs fine, although it doesn't seem to rev quite as smoothly. It's hard to describe but there's a slight vibration when at lower RPM and high engine load. I've got a JB4 on it but most of the time I run it in bypass mode; I'm a little nervous cranking the boost up with these weird symptoms going on; I don't want to risk one of the cylinders leaning out.
It sucks that there doesn't seem to be any one smoking gun that could cause all this stuff... Gunked up intake valves? Injectors? HPFP? $$$$$$$$$$$ cha-ching... good thing my neighbor is an independent BMW mechanic
It's been a while since I've looked at this but I'm happy to report that this issue has been resolved with my car. All six plugs were replaced along with one injector. My car has NEVER had a walnut shell carbon clean. The dealer was able to detect misfires in the engine that followed the plugs around when swapped; they replaced all six and verified that the misfires were gone. They then removed the plugs one more time and detected fresh gasoline on one of them; that particular cylinder's injector was leaky and so it was replaced. Everything's been running fine for the past month or so on these repairs. I have about 72K on the odometer.
I'm told that these engines are VERY sensitive to the plugs and the plug gap. If the tech who replaces the plugs is even remotely careless and accidentally touches/bangs the business end of the plug against the threads when inserting them, that alone may be enough to mess them up and cause potential misfires.
The other thing to note is that prior to having the dealer investigate, I had a local BMW independent repair shop take a look and they weren't able to resolve it. They couldn't detect misfires/codes but the dealer could, so the dealer must have some special diagnostic equipment that's not available to an independent shop....which is unfortunate. I finally broke down and went to the dealer when they advertised a 20% off service coupon!