Hi everyone. I have had my '10 M3 since mid June and have had the check engine light come on 3 times due to carbon buildup on the spark plugs. Each of the previous times the dealer cleaned the plugs and turned off the light. This time I am going to have them look at it more throughly. Any ideas on an underlying reason this keeps happening?
How's your gas mileage been? Carbon deposits are generally due to an excess of fuel in the oxygen/fuel mixture. Could be a bad O2 sensor, bad fuel injector, or an issue with the computer that regulates the mix.
The dealership should be able to hook up your car to their diagnostic equipment and see what's out of whack.
Been getting very steady 29MPG since I have had the car.
The first time I took the car in the dealer cleaned the plugs and said it was due to starting and very briefly running the car and then turning it off (said this might have been done at the dealer before I got the car).
The next time it was 3000 miles later and they just cleared the light and held the car at 4,000RPM for a few minutes to burn off the carbon as they just squeaked me in between other appointments becauase they wanted to look at it quick to make sure it wasn't a bigger problem and I could still drive it.
I put the K&N air filter in from my '06 M3 about 2,000 miles ago, so I got the light twice before that was in. Never had this problem on my '06.
Could it be a EGR valve problem? Seems like if the EGR valve was stuck open, it would increase exhaust gases being recirculated, leading to more carbon deposits. That's the only thing I can thing of.
Thanks for the thoughts, will remember to have them check that. I have an appointment Friday afternoon to have the car looked at. Any harm in driving it until then or should I try to borrow another car?
My old car, 2002 Pontiac Grand Prix, had a thing where if the check engine light came on, the car would go into "safety mode" it would drastically cut performance as well as mpg just to make sure whatever the problem was wouldn't make the engine go KABOOM!
I think it should be fine for a couple of days, but I don't know for sure. Most likely, your car just won't run very well (rough idle, less power, etc).
Don't know for sure. When My P5 had a bad EGR valve it performed just as Drrick described, rough idle, low power, sluggish acceleration. Definitely get the vehicle checked ASAP as the carbon buildup will get pretty bad and can screw up emission of left for too long.
They are both part of the emissions system, but they definately aren't the same thing. Based on that information, I would say the EGR is a much more likely cause. Good information in those articles, for the curious such as myself
did a quick search on the two and they don't seem to be the same. something to bring up though when I take the car in. It does seem to idle a hare rough right after starting.
Yeah, I hope they fix it. They should have fixed it already by now, and I hate that they just kept sending you out there again and again with a potential problem. Thats really strange. I hope everything works out!
i know exactly why engine light went on, he Most likely put gas in his car and didn't twist the lid until he heard 3 clicks , that's exactly what my friend did to her car we took off the light with computer, then when she checked gas lid it wasn't twisted all the way. it even warns you that if you don't tighten it the light may go on
Maybe you should read the OP again. I don't think a loose gas cap is going to cause carbon buildup on his spark plugs. I also don't think that cleaning the spark plugs is going to tighten the gas cap (if the gas cap was actually causing the CEL).
Yeah, not to mention, this gas cap we have on the 2010's is probably the EASIEST gas cap I have ever had on a ca, its like barely even a turn, and its clicked 3 times...just sayin...
I didn't even realize you were from Cleveland until I saw that which prompted me to look at your location, lol. Do you go to Cleveland State? I see a 2010 3 in the parking lot every once in a while on my way in to school. That would be pretty funny if it was yours...
We dont have Getgo's over here, but I have heard they are pretty decent from my homies in the mid and south. I always stick with either Chevron or Shell, in that order. If there is no chevron in sight, I will go to shell. THey are both super-clean gasolines, and run really well, even on regular.