First of all your car is young at heart, at least
in miles if you have not beaten it while driving. Most of your equipment has not reached the end of their life cycle, and I would guess your 02 sensors are included in that. (with an expected life of at least 100,000 miles)
Next I'll hazard the guess that the sealant you used is not responsible for the rough running.
Now I'll say that your maladies are complex enough to warrant a service trip to your local knowledgeable BMW dealer with a mechanic who works on these complex engines all the time and has a better feel for what goes wrong and what it looks like than we ever will from the long distance we are from your engine. This is not the time to become the quick change guy on your block! It might become way too expensive even without finding out what is wrong.
Please come back and let us know the ultimate solution you find is correct?
Footnote: a new battery does not affect the initial start-up of your engine.
DONT CHANGE YOUR SENSORS YET!!!
Before you spend $250 and a Saturday afternoon on cold concrete, check the condition of the duct between the airbox and the intake manifold. This is two lengths of flexible rubber hose about 4" in diameter connected in the middle at a swivel point with hose clamps. Use a flashlight, mirror, and your fingers to see if you have any cracks, holes, etc. in the ducting (even little ones will eventually trip service engine codes). The bottoms of these in particular (where they are hardest to see, reach, and feel) rot out letting unmetered air into the system. This unmetered air will trip E3 and E4 codes. both sections of the duct will only cost about $60. The section closest to the airbox is a 15 minute replacement. The lower section is a bit tougher (but not too bad). I have a 2001 330i with about 71K miles. So far, I've had to replace the duct piece closest to the airbox twice. If you are tripping these codes almost daily, I suspect you will find significant holes in this ducting.
Autohaus has great pricing and I'll be buying 02
sensors there myself when I need them. But also remember they are in business to SELL sensors, so take with a grain of salt the dire picture they paint of a failing sensor.
I've got an almost 7 year old car with 77K miles and I just hooked my car up to a friend's PC with diagnostic features that allow you to read the real time output of the sensors. All four sensor outputs were right in the center of the correct operating range! I'm still betting your sensors are not the problem and urge you to try the inspection that DeadEd suggested right below here.
Just to establish common ground, the pre-cat sensors are really the only ones that count with regard engine management. They are the primary feedback sensors. The post-cat sensors are there mostly to monitor whether you are exhausting clean air for emissions purposes. You could care less about these as far as proper engine running is concerned.
All that said, I like to replace parts ahead of time to keep all pure myself, so by all means put your new sensors in. What I'd really appreciate is if you come back here and describe if that changes things, or whether you have to continue to troubleshoot your car to find what ails it.
Dead Ed, is most certainly NOT BRAIN DEAD!!!
Ok I thought... the sensors are still $250. That's still some good coin. So I read DeadEd's post, and immediately called Autohaus and told them to hold my box for one day. They said they could not, only to cancel it, so I cancelled at no expense to me.
I had to wait until my wife came home tonight with the car. I thought no big deal taking out the air box, ten minutes, I'll clean her K&N filter right away. So I got the filter box out, and what do I see??? No, no cracked hoses, just the big cold air intake totally off and away about an inch from the alternator cooling duct. Jackassses at the Stealster. We had the alternator replaced under the CPO warranty a couple years ago. The so called BMW tech just simply never put it back on. Could of it fallen off? Absolutely not, the duct fits together very tight, and I had to wrestle with it for about a minute. No accident, he just didn't bother to hook it back up! Amazing. The Stealster. But we were happy for the alt. All it had was a bad bearing that would only make a grinding/scraping noise when -cold only- for -only a few minutes-. Sounded exactly like a water pump bearing. So instead of just pressing on a new bearing, we got a whole new re-built alt. But I digress...
So I fixed that, and went on a hose hunt. Nothing down there. I knew I had to follow the main big bellows in behind the mass air sensor. That big bellows looked good and pliable. Two small lines come out the top of this bellows, all looked fine. These both go from rubber tubing to metal in a short distance.
But waaay back in, almost against the firewall, a -second much smaller bellows hose arches in to the left toward the engine. Looked it all over, seemed flexible too. Just about ready to call it a day and put it all back together when I remember DEAD ED saying to feel all over, and even use a mirror.
I thought what the heck, I have a little dental mirror that my dentist never missed. (; Holding it behind this small bellows hose on the outside curve where all the strain would be... bingo! Several small cracks, three near one groove, and another crack up one groove. And that's only what I can see with the mirror at this point.
So... HATS OFF TO DEAD ED. THANK YOU VERY MUCH ED!!! YOU DA MAN!!!
I'll put it all back together for now until the parts arrive. Then I'll let you know the results.
Excellent that you found the problem, hopefully.
You might have put some duct tape over the cracks on the inside of the bellows temporarily to see if that changes things.
You've hit upon another of my pet peeves. Mechanics who don't pay attention are all too common. Sleep walk thru the job that you're paying them $100/hr for. I've had it happen too many times that I have to go back over their work to make sure my car is together properly.
That's why I hate to let my car disappear into the dealer's bays without me.
Re: Excellent that you found the problem, hopefully.
Your absolutely right Stinger! And just to prove it was no accident and that the cooling duct just fell off, I see now that it -is supposed to- have a hose clamp around the neck. The sad thing is this duct is HUGE and had to be right in your face while finishing up the alt installation. I actually first noticed it when the air box was still in place with just a flashlight!
good stuff--did you know that
the mechanics are required to take a class on --how to mess up the job. If it was not the dealers shop, I would say that it was intentional for a smart mechanic who wants to see you again soon.
"smart" mechanic? "Smart"=dishonest.
Unfortunately, you really have to KNOW cars or trust your mechanic. Too many relatively simple ways to tack on extra services and parts.
What a shame that we're having to have these
comments posted here. And most of us know enough so as not to be 'taken' by some lame description of work needed.
I believe it was the latest R&T where someone wrote in that the quick change oil place told them they needed an engine flush because their oil was 'lumpy'! Some people have seemingly complete contempt for their fellow mankind.
As far as repairmen are concerned,
I run a small building in Manhattan and watch over every contractor who comes into my building to check out their skills, work ethic, and honesty. I'd never let them work here without constant supervision because they love to cut corners. I oould tell you stories.
Wanna put new pre-cat sensors in; can't do any harm, not too expensive, and is a relatively simple job. Hope it helps.
Do the sensors, replace the hoses, and let's see what happens.