Knock/Ping
Thread Starter
Member
Joined: Apr 2018
Posts: 151
Likes: 95
From: Connecticut
2013 E550 Sedan, 2005 E500 4matic Wagon
Knock/Ping
So lately I have noticed the 550 is knocking/pinging like it has crappy fuel in it. I cannot feel any reduction in power or response. This only happens (as I can hear) at 25-35 mph under light load....like slowly rolling into throttle. I can only hear it when my windows are rolled down. I keep over a half tank of premium in the car at all times. I use 1 gas station. I'm going to try a couple of things here first. New gas station, then a direct fuel injection additive just to rule out fuel. If it's not that....I would possibly suspect a failing delivery pump (I would think power would be affected and a CEL), or the timing chain is getting worn to the edge of spec ( I would also think power and CEL). I usually drive this car 50/50 sport/economy. Does it in both settings.
Any thoughts?
Cheers!
Any thoughts?
Cheers!
Thread Starter
Member
Joined: Apr 2018
Posts: 151
Likes: 95
From: Connecticut
2013 E550 Sedan, 2005 E500 4matic Wagon
Side note....have searched the forums and read on similar topic, but no real explanation or solution. My pump has 93. I am aware the vehicle will retard timing when the knock sensors pick up detonation. I think it only does that when the load is over 30% relative to speed. In my experience timing retard under any load can be felt.
Super Member
Joined: Feb 2019
Posts: 681
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From: FL
2012 E550 sedan 2019 E63 Wagon
Side note....have searched the forums and read on similar topic, but no real explanation or solution. My pump has 93. I am aware the vehicle will retard timing when the knock sensors pick up detonation. I think it only does that when the load is over 30% relative to speed. In my experience timing retard under any load can be felt.
You are going to have, to monitor you sensors in real time with a scanner. Also check you exhaust for leaks and loose heat shields. I would have someone else rev the car slowly thru the RPM range, while you look around for resonance.
MBWorld Fanatic!
Joined: May 2018
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From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
If your regular workshop has in cylinder pressure transducer and 4 channel Pico Scope, maybe it can shed some light to how is the actual firing waveform on any suspect cylinder/s they may find,
which caused the knock. An experienced person/tech can tell A LOT from cylinder pressure waveform.
which caused the knock. An experienced person/tech can tell A LOT from cylinder pressure waveform.
Thread Starter
Member
Joined: Apr 2018
Posts: 151
Likes: 95
From: Connecticut
2013 E550 Sedan, 2005 E500 4matic Wagon
If your regular workshop has in cylinder pressure transducer and 4 channel Pico Scope, maybe it can shed some light to how is the actual firing waveform on any suspect cylinder/s they may find,
which caused the knock. An experienced person/tech can tell A LOT from cylinder pressure waveform.
which caused the knock. An experienced person/tech can tell A LOT from cylinder pressure waveform.
Thread Starter
Member
Joined: Apr 2018
Posts: 151
Likes: 95
From: Connecticut
2013 E550 Sedan, 2005 E500 4matic Wagon
Just found out the gas station I WAS using has been nailed 3 times in as many years for fuel grade. Makes me think the coffee I get from there is somehow always decaf.
