C63 amg knock pinging on startup

[Wheelspk]

Hello,

My 2012 c63 has 48,000 miles on it, totally stock car.

Only on warm-start up just for 1 sec as the car is about to start i hear a loud pinging sound like the car knocks asif it has bad fuel or bad spark plug, it does not sound like lifter rattle or tick.

this knock/ping only happens if the car is warmed up Never on cold start and is very audible from in side and our side.

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car idles very good and drives normally not pinging even at wot or accelerating but i do hear a faint bussing sound coming from the right side of the cabin as I accelerate slowly from 2500 rpms in gear only never when i rev in neutral gear or parking, even if i rev it i don't hear any knock its just only warm startup.

please help me figure out what this is as im really worried about it .

thanks

 

[Jobsworth]

Have you ever replaced the fuel injectors?

 

[Wheelspk]

Have you ever replaced the fuel injectors?

No never.

 

[Wheelspk]

Car also just gave code with check engine light
p0746 and 0750 went in to limpmode
Bank 1 and 2 too rich

 

[Jobsworth]

I would pull your injectors and get them tested. These are known for sticking with age, and in very bad cases can hydraulic lock and bend the rods. If you have one or more dripping injectors it could feasibly give a rich mixture on start up. If left for a while it’ll drain past the rings and into the sump. Remove the oil cap and sniff in the cam cover. If it smells of petrol you might have a clue

 

[Wheelspk]

I would pull your injectors and get them tested. These are known for sticking with age, and in very bad cases can hydraulic lock and bend the rods. If you have one or more dripping injectors it could feasibly give a rich mixture on start up. If left for a while it’ll drain past the rings and into the sump. Remove the oil cap and sniff in the cam cover. If it smells of petrol you might have a clue

Got the injectors cleaned they were perfectly fine all equal and flowing good

I still get start up knock

Any suggestions?

 

[Wheelspk]

Anyone?