Engine Went Mad... oh not again!!

[Shipkiller]

I supposed it's ok to poke fun at someone now and then. I'm a big girl so I can take it.

To clarify my post, I was suggesting that the method of troubleshooting and the specifics that the people in the thread were following might facilitate the OP through the thought process of someone chasing down a similar symptom. The car's make and model are entirely irrelevant because the laws of physics apply to the internal combustion engines of any make and model in exactly the same manner. If you went to a Subaru or Porsche forum, you'd see a very similar set of threads like the one I posted - nearly identical in the sort of troubleshooting efforts those owners would go through for the same symptoms.

Anyway, I just hope that there might be a bit of information which may cause an 'aha!' moment for the OP and that my post might be able to help. These issues are buggers to get sorted as they say but some of what's in the thread I mentioned would be relatively simple things to try at home and don't require a mechanics level knowledge, just a few minutes time on several of the ideas mentioned.

I had an 06MR and had an extended crank / oscillating & rough idle condition which was never identified. At that time, there was a strong suspicion that fuel quality was at fault but the dealer and BMW couldn't figure it out. I use Shell in my 07MR which is BMW recommended here in the U.S. and with the 07MR, it seems to work quite well. I wasn't using Shell in my 06MR but I stopped going to the conveniently located fuel station on my way home since I had pretty much exclusively used one location back then.

The OP's issue could be related to fuel quality which varies from season to season, region to region (geographically) and by fuel company. You'll start to see more threads on rough idle and hesitation / stumble complains when the weather turns cold. MBTEs can cause a waxy type build-up on the intake valves and the build-up disrupts the A/F mixture from proper stratification prior to the combustion event which can cause a lean condition. There are tons of threads on fuel related issues and sometimes, without the proper test equipment, the person at home is left to his own random troubleshooting effort which can be very frustrating for someone unfamiliar with the way engine systems operate.

I hope the OP gets his problem sorted!

A well thought out and articulated post.

How refreshing....

 

[Andy]

A well thought out and articulated post.

How refreshing....

How very true.. Car_Girl you're welcome to slap my wrists if you'd wish

Fuel is a very sensitive thing in the S54, when I had this exact issue as a one-off I assumed a fuel quality problem & never saw the issue again. Agreed - if you're having this more than once force yourself to change fuels for a while and see how it goes.

My symptoms were exactly the same - and totally isolated in 54,000 miles - so that's enough for me as a diagnosis.

 

[Anonymous]

Thanks Andy, no need for any wrist slaps, although I have to admit that it took me a little while to craft my response without offending anyone who might be reading through the thread. These forums in general have been so useful to all of us, there's no need for anyone to get upset about anything but I see it happen all the time.

It's good that you've convinced yourself that fuel quality was the root of the issue you were seeing with your car. I thought the dealership was full of it when the Sales and Service guys told me to exclusively use Shell which is what I try to use now. Occasionally, I stop at Mobil which hasn't been a problem for me and I only use the highest octane available. So far, so good, but, now that the weather is turning cold, I'm seeing a difference in my cold start performance and this is WITH Shell as the fuel. Just last week, I started the car with a normal turn of the key and it took quite a bit longer for the crank cycle, then when the engine fired up, there was a bit of sputtering at the start, then a rough idle but after about 30 seconds, maybe less, the idle came back to what I'd call 'cold normal'. I'm going on my 3rd cold season now and this is how the car behaves during cold starts when the temps drop into the 30F range.