So ever since I bought my MCS (2003, used, bought 2 months ago) it has had a wierd little idle glitch. Probably once every 20 or so times I stop at a light, it will start to idle very roughly for about 10 seconds, almost like it is going to die and then smooth out by itself. I brought this up with the SA at Fife Mini NW and he claims it is supposed to do that. He says that the emissions system captures unburned fuel vapors and then every so often runs them back through the intake system to burn them and that makes it idle rich momentarily then it goes back to normal. He said this is a known issue but that's the way it's supposed to work. He also said not to rev it during that time because it will flood the cylinder walls with gas which is not good for the engine. He claims that the engine does this fairly frequently but you'll normally not notice it when you're driving, only when idling.

Does anyone else experience this? I am very suspicious of this explanation as I can't imagine it wouldn't cause all kinds of issues with customers taking it back in for warranty service.

 

it gets a rough idle because the computer leans it out and it starts to get studder. a blip of the throttle will get rid of it. Mine use to do it alot.



EDIT: I guess i should read your post first lol. but your SA dont know squat. it leans out and stumbles like i said above. I think they have a reflash for this at the dealer that takes care of it.

 

My '03 MCS does this. However, I did notice that it did it less after I removed the resonator from the exhaust system. Maybe just a coincidence.
Also, I did notice one time when I had my black '03 MCS, I was getting gas and it started to do it, a good amount of black smoke was puffin' out the tailpipes, which would lend a certain amount of credibilty to your SA's explanation.

 

There is nothing to capture unburned fuel from the engine. He did a poor job of explaining the EVAP system which takes fuel vapor from the gas tank and stores it in a carbon canister. At certain intervals, the purge valve opens and lets the vapor content of the canister into the intake stream to be burned. I believe some earlier ECU software activated the purge valve at some inopportune times. Have your dealer update the engine management to the latest version
--Dan

 

Thanks...

Any idea how much an ECU update costs if you're out of the maintenance period? Is this covered under the drivetrain warranty?

 

Should be covered under the 50,000 mile 4 year warranty.

 

My 04 used to do this alot. I got the upgraded ECU flash a couple of months ago and it has stopped. They also gave me a sheet on top tier gas, which says the gas you are buying could also be the cause of the idle problem and hard starts. I don't my copy handy, but I have since been using Kwik Trip gas because it is one of the recommended ones on the list. No more rough idle, I did notice prior to that I would go long periods of time and it would be fine, so the gas could have been part of the problem.

 

I get that occasionally and my WB A/F gauge shows 17/1 ratio :impatient Blip the throttle a few times and it usually goes away...