my 225q has a very lite miss at idle. i just replaced the plugs, so thats not it. the car is almost at 50k miles. im thinking about cleaning the tb. how hard of a diy is it? oh and can ethanol cause this or any others problems? ive noticed that most fuel pumps in fla. have 10% etahnol on the the pump.

 

My guess its the throttle body or inter coolers. Its a hard DIY for the mechanically inclined. I was lucky and done for free.

 

Its not the ethanol, its the blow by that pool in the ic(s) and tb. You can easily clean the tb by just removing the TB hose and then the 4 allen bolts on the TB, after that remove the hose and plug and you can move it to spray cleaner on it. While you are at it, change the fuel filter also

 

so after i clean out the tb, if the problem corrects itself only temporarily, i should clean out the ic's and maybe get a catch can? idle was so smooth when i first got it, that i often wondered if it was on. after a couple days of beating on it, the little tick in the idle. just appeared 1 morning. maybe i knocked some sludge loose giving it lots of peak boost. its been a little rough starting lately. only in the morning.

 

change the fuel filter

 

try the seafoam....only do this if u plan on changing your park plugs soon after....