Hello all

coming from a 204 c63… moved on to a jeep srt and decided it was time to come back to reality. I bought a 2018 c63 today in Florida cpo. I went for a test drive before signing and everything was perfect.. on the way back to my hotel I gave it about 75% throttle and the car fell on its face, cel and misfiring at idle. Turned the car off and back on again and the cel disappeared. Repeated the 75% throttle and now the cel is constant but idling seems normal. I called the dealer right away and they told me to bring it over in the morning. I’ve read multiple posts about bad coils/plugs and also a few about bad gas that caused this. Can you guys please give me some advice about what to do at the dealer tomorrow? I could see them throwing the keys to some jerkoff and telling them to fill the car and maybe there’s 89 in the tank instead of 93 could that cause it?

 

*****Scan tool and pulling the codes will very much help identify the problem. Yes, it could be bad gas, but just as likely a bad coil/plugs, or any number of other things. Thankfully, the car is a CPO so the dealer should be able to fix the problem and let you know what the problem was. These cars are complicated but a good scan tool with an experienced mechanic can narrow down most problems very very quickly.

Good luck and hope it is a simple problem.

 

thank you buddy. I left my scanner home that’s the first thing I was gonna get tomorrow before I head over there but I’ve read some posts about the car throwing a cel without any codes so I was just trying to get some input beforehand. Really appreciate it

 

My bet is also a bad plug or coil. In any event, you're under warranty so nothing to worry about.

 

thank you bud. That’s true but I have to get back to ny.. how bad would doing 1000+ miles with a bad plug/coil be for the motor?

 

*****OMG please do not drive 1000+ miles without knowing what the problem may be. Get the dealer to fix the problem or at least diagnose the issue so you are better informed as to why the car is misfiring. If the problem is just a lazy coil causing intermittent misfires ok that will reduce performance, fuel economy, etc.. Not ideal.. However, if the misfire is as a result of the plug failing due to a loose or cracked insulator from prior detonation, or a bad plug, etc... it could cause catastrophic damage to the motor if the insulator breaks up and is flopping around the combustion chamber at 3000+ rpm or whatever for a 1000+ miles! The chance is there that it ends up scoring the cylinder walls, or damaging a valve seat where every molecule of air and fuel passes through during the intake phase before the ignition phase. You damage a valve seat (unlikely, but alot can happen in 1000 miles!), and you now basically have a leaky cylinder, possible blowback through the seat, a damaged valve, and a monster 4-5 figure repair bill due to a $14 spark plug falling apart and being driven that way for hours and hours. Engineers spend a lot of time designing combustion chambers and it is critically important the quench area not be damaged from stuff flopping around in there that is not fuel and air.

Obviously, if it's just a bad batch of gas, forget all of the above and have a safe trip. But - since you have a dealer and a CPO car please take the time to let them identify and fix the problem for you before such a long trip. Road test the car before the long trip home so you know the problem is fixed. A few minutes of your time verifying stuff can save you whatever money you saved being squandered because something major breaks as a result of a broken plug, bad coil, or faulty injector, etc..

Anyway, not to scare you, but the C63 is not a cheap car to fix. Easier and cheaper to be pro active and spend some time making sure things are fixed versus risking a broken AMG motor that has remarkably expensive parts and lots of labor time if the motor has to be opened up to get to those parts to fix what got broken.

Good luck, thankfully you got a CPO versus a private sale with presumably no warranty once money has changed hands.

 

Definitely don't do that. Get it addressed and fixed before making that trip. Plugs and coils are an easy job for the dealer. I got a misfire and changed the plugs in my garage the next day. Good thing I did as the ceramic insulator broke and was covering the electrode. Had it come all the way apart and dropped into the cylinder, it would have likely been a lot worse.

 

Thanks for the help guys. It was a misfire on cyl 2 and the dealership was awesome.. long story short I wound up switching it for a c63s that was optioned a bit better. The car is insane I’m in love

 

Now that's gotta be the best dealer visit outcome ever. Haha.