14e550

I have a 2014 E550 coupe stage 2 (downpipes and tune), 77,000miles. I went on a trip to Mexico this weekend and switched to my "100 octane tune". After a couple pulls I felt the car "sputtering" at idle. It ran fine and still runs decent except the sputter at low rpms. It threw a P21A0 code "air fuel mixture imbalance at cylinder 5".

I plan on removing my tune and seeing if could be the culprit. Other than that has anyone encountered this code or have an idea on what can be done to address it? (Not sure what other information is necessary)

camgc450

I'm having the exact same issue with my 2016 c450 amg. I'm also stage 2. My burble has been acting strange the past few months so my tuner advised that I try adding some octane booster to see if it would fix the issue. After the octane booster went through my car has the exact same CEL as you and idles like trash. it shakes slightly under 1-2 mph. I'm wondering why... I've already done spark plugs, tested for vacuum leak, did cylinder 5 injector, swapped around coil packs... not sure what happened. We are having the exact same issue. Super strange.

Boostedbenz12

Get rid of the burble tune they are not good for our cars. I had the weistec burble tune on mine and had the same issues. Removed it and everything was fine.