Rookie48, Thanks for checking up on me.
I still have not fixed it.
I just replaced the valve cover gasket (it was leaking), rebuilt the VANOS and replaced the exh side cam shaft position sensor and smoke tested it. Still the same misfire codes.

Im looking an Craigslist for something else.
Its a shame, I have spent over $2000.00 on this problem.

SarTech:

I feel your pain.... I have been extremely lucky as the independent BMW shop I use (Moonlite Motorwerks in PA) have been sympathetic to my issue, and have not been charging me labor for very visit. The regional BMW shops sometimes go to these guys when their techs can't figure issue out. But this issue on my X5 has been challenging to say the least. The misfire only codes across all cylinders is baffling...

Hopefully we will solve it shortly... I'm not always in a good traffic position to shut off the truck and restart it to clear the limp mode! Glad it's a 5-speed manual!


Rookie48

Rookie48,

Mine is also a 5 speed manual. I wonder if that has something to do with it?
Maybe the vibration created by a worn and aged clutch is picked by up as a misfire.

SarTech:

My clutch is new, at least replaced about 25,000 miles ago. When I bought the truck (used), the previous owner had that done.

My truck has almost zero vibration, very smooth running on the highway, except when it goes into limp mode.

The 5-speed definately puts the engine through more on/off throttle cycles than an automatic would. I don't think there is any sensor for engine management from the manual transmission that would be causing issue.

I double-checked vacuum line connections today, even sprayed brake cleaner at the injector and intake gasket locations to see if it would change RPMs... No change...

I'm convinced this is an isolated issue given that the truck runs fine except at very little throttle at highway speeds (high intake vacuum). What is making it hard is the misfire codes for all cylinders with no other codes... Yet until the truck enters limp mode, I'm not sensing any loss of power.


Rookie48

One more thing I should ask you - does your X5 MT consume any oil between oils changes?

I change oil every 5000 miles with Total Quartz Long Life synthetic (5W-30), and have done a BG motor flush twice this year to clean out any carbon or gunk build-up. I have had the CCV and all hoses replaced as well. I get anywhere from 1000 to 2000 miles before having to add a quart of oil. It seems sporadic, and I'm not sure if it is related to the misfire issue or not.


Rookie48

Rookie48,

Yes it does consume a lot of oil. About 1 qt, maybe a little more, every 1000 miles.
I have replace the CCV system, valve cover, oil filter housing to engine block gasket and the compression is good so I assume that it is burning the oil. But the spark plugs don't appear oily.

I might try another fuel pump and new filter/regulator next.

SarTech:

I have another thread going on my truck at:

http://www.xoutpost.com/bmw-sav-foru...e-misfire.html

Maybe it will help you as well.

At this point I'm somewhat convinced there is a small vacuum leak at high vacuum conditions with the throttle just off of closed. But finding it is a buggar!

...and I think the oil consumption MAY be related if this is indeed a lean condition.

My theory - lean cylinder condition allows for some oil film to be burned off the cylinder wall.

-If the VCG and 15 grommets were replaced
-The lower intake elbow is good (check the elbow for cracks and the 2 vaccuum hoses and replace those as well)
-Throttle body is clean and gasket is good
-ICV is clean and mounted securely
-CCV is replace with good parts and hoses are secure on the CCV, and dipstick guide tube is clean/clear for the CCV drain
-vaccuum hose from the EVAP canister is good (there is a vaccuum tube at the back of the intake manifold
-If fuel filter was replaced, the small vaccuum hose is not broken
-Coilpacks and plugs are verified to be good
-Battery is in good condition (needs enough voltage to fire the coils)

I'm pretty much out of low throttle high vaccuum misfire solutions lol

Good luck to you guys

SarTech:

By chance are you having any hydraulic lifter noise on your 3.0i?

New theory might suggest the lifters are "sticking" at higher RPM's, causing the valves to not close in time with the ignition, causing a "misfire" (power drop).