My MCS has an idleing problem. When the car sits at idle it runs a little rough. It seems to isolate between 1100 and 900 rpms. The car had this problem when i first purchased it. Since then i have added a 15% reduction pulley, a drop in K&N intake filter, and better spark plugs. Adding these upgrades has neither worsened the problem nor improved it. Any suggestions?

 

What plugs are you currently using?
Have you tried running some injector cleaner through it?

 

I am using bosch platinum plugs... the car was idleing rough before the plug change anyway... i tried injector cleaner with no luck...

 

My car was doing that on stock plugs until I went one range colder. I use NGK BKR7EIX.
What kind of injector cleaner did you use? I use Chevron Techron.
It may take multiple tank fulls to fully clean abused injectors.

 

Minr ford the same when sitting for a minute or so with the A.C on it willl start chugging and i noticed it puffa black smoke...hmmmm?

 

My 2004 S idled fine until I received the most recent ECU flash (unrequested BTW). Now it does have a rough idle occasionally.

 

my 04 S is idling pretty rough too, almost like its going to choke off at any second. Not really sure what the cause is. and it doesnt do it every time. so its hard to replicate for the dealer. i only have 28k on it.

 

I am having the same exact problem with my 2004 mini cooper s. its almost as if it is gonna shut off at any second... it gets very disturbing at times but i have grown to just live live with it..... but i should try and get some new plugs and wires and maybe some of the fuel injector cleaner like you guys are saying....

 

yup my 04' mcs has a rough idle too, more so when its cold. i remember there was a big thread about this a while ago. i think its the ecu or something from what i can remember from the thread. well in the bright side it sounds like the car has an upgraded cam

 

so have any of you actually have the car quit during the rough idling? Mine hasn't but i usually tap the gas to get the rpms back up before it would even have a chance to shut off

 

most copper s's will idle a little rough, i dont think it is anything to worry about

 

just once it was rough enough for me to think it was about to die, but yeah the quick tap of the gas always smooths it out. but it also smooths out if you leave it alone. i agree with ministubidfun that this is pretty common and so far it hasn't shown any affects of it.

 

mine idles just fine.....but I make sure I run a top teir (Chevron) gas in it and we also don't have "summer" grade fuel where I live.

 

I have worked on 3 that were rough..
2 were fixed by using the dereiot Tuned BPV the 3rd has not done it yet

I have a photo of the OEM BPV that came off of one in my gallery

 

Mine still does this from time to time... especially running 91... but when running 100 never does... I wonder if it will do it on 93... I'll find out soon! also I have no bpv so I am thinking it's just gas... the car is not made to run on such crap as 91 even though it can...

 

 

I know I'm just one person....but I have an 03' and I run 93 in it with no problems....so maybe it is the gas? We don't have "****" gas either like other states...

-Cody

 

 

littlehand is from SC, no "****" here baby!

 

I use 93 octane. I also have a marathon/speedway/super america gas refinery about 20mins away. so the gas doesnt have that far to travel to get to my local stations. plus i have tried different brands (BP..Exxon) with no differences as of yet.

 

2004 MCS here that every once in a great while will stumble while sitting at a redlight. Nothing a quick blip of the throttle doesn't cure. Kinda like what you have to do to a muscle car with a big ole nasty cam in it...

 

I just hit 30K miles on mine and having the same problem, and mine is completely stock!!! (Well, at least for now...)... I run 93 on mine since there is almost no gas stations selling 91 near where I live...

 

Had this problem for at least the last 2 years. One software upgrade helps then the next one undoes the benefit. The next upgrade will help and so on.
Always 93 octane. I believe this problem is in fine print in the back of the owner's manual as" a cute little quirkiness". Learn to l ove the quirk.

 

Had this problem for at least the last 2 years. One software upgrade helps then the next one undoes the benefit. The next upgrade will help and so on.
Always 93 octane. I believe this problem is in fine print in the back of the owner's manual as" a cute little quirkiness". Learn to love the quirk.

 

Mine does it too. It is not consistent. Only once in a while. Doesn't seem to be any particular conditions that I can put my finger on -- might be hot, cold, but it always seems to go from a regular idle into that sort of loping rough idle after sitting at a light for anywhere from 10-20 seconds.

It has never actually died, but it has come really close.

Did it both before and since my Fireballed tune. Started about 35-40,000 miles, I think. Does it so rarely, though, that I have never actually complained about it.