For the last few months, I have notice that the exhaust is very rich smelling. I recently took it to the dealer, and they did an update on the ECU, and I was hoping that it would take care of it. It didn't. It also hesitates when I step hard on the gas, almost like it is bogging it.

Any ideas? I have an 04 MCS JCW.

Thanks.

 

Sorry, no ideas just a sympathitic ear. I to have an '04 JCW. I think it's always run rich. It almost always takes 2 attempts to start in the morning and quite often bogs down and stumbles at idle waiting for the light to turn green. Only had the hard start problem occasionally...took it to the dealer for the stumble. They updated software...stumble didn't go away, but the hard start got a lot worse. Oh, one idea..restriction somewhere in air intake. Leaves, dirty filter, etc. Obvious, but sometimes overlooked.

 

have you noticed an increase in fuel consumption? I have read that all BMW products are tuned rich to some extent but if something seems different then possibly something else is going on. Have you possibly switched gas stations?

 

Mine smells rich also, but I don't hhave a stumble and I can clear 33mg on my daily commute of Hwy/City. Maybe it's more common than we think. I didn't smell it until a couple weeks ago when I let the car run in the garage for a couple minutes when I ran in the house. Not horrible, but still... Smelled like my old BMW bike.

 

Well JCWs do have larger injectors...so obviously there is more fuel being dispensed. It must run more rich than most cars I guess...

 

Do they also have a distinct smell under hard acelleration? I was passing a friend the other day and later that afternoon he jokingly asked if I was running ethanol in my MCS as it smelled like alcohol behind me as I was acellerating hard.

 

I haven't changed anything lately. I havn't seen a difference in the fuel mileage either. It sounds like it is sort of common. I wonder if it does have something to do with the larger injectors. I will have to keep an eye on it. Now, if I could get rid of the stumble and hard start, then I would be happier. They have "updated" the ecu twice now and it hasn't helped.

 

I've noticed something odd on my '03 MCS JCW...........it used to take two tries when cold (like first time in the am) to get it to start and run almost every time, after the second try it always ran fine. Lately, instead or releasing the key the moment it fires, I hold it engaged just a tick longer, it starts first time and runs fine when I do this.........very interesting..............
I've never noticed it smelling like it's running rich tho........maybe try a different brand of fuel? I remember one person on the forum reporting a major change in the way their car started and ran after changing to a different brand of gas, from one major brand to a different one............