Pinging/Knocking/Detonation? Sounds like rocks in the engine on acceleration..
Thread Starter
Member
Joined: Sep 2005
Posts: 168
Likes: 26
2017 C300 Coupe (C205)
Can you take a video so I can hear some audio of the sound? Most modern direct injection engines do have a very constant ticking, like a sewing machine during idle. The ticking is from the high pressure injectors. Your engine is designed to run on premium, but if lower octane is detected, the car's ECU will go into knock protection mode, lowering power output to prevent detonation. If you are experiencing detonation your CEL will go on.
I've had intermittent knock before on OBDII cars and I've only seen the CEL come on when it happens for an extended period of time. In our case, it happens for a period of less than 2 seconds and goes away as soon as you let up on the gas and get back on it. Currently there is no CEL on her car resulting from this.
Senior Member
Joined: Mar 2014
Posts: 339
Likes: 35
From: Nevada
2014 E63S, 2018 GLC 300
As I said before, it happened once during a 20 minute drive of me hammering it off the line and passing trying to replicate it. I probably could get a video but it likely wouldn't happen for another 2-3 months when I get the chance to head back out there and set it up.
I've had intermittent knock before on OBDII cars and I've only seen the CEL come on when it happens for an extended period of time. In our case, it happens for a period of less than 2 seconds and goes away as soon as you let up on the gas and get back on it. Currently there is no CEL on her car resulting from this.
I've had intermittent knock before on OBDII cars and I've only seen the CEL come on when it happens for an extended period of time. In our case, it happens for a period of less than 2 seconds and goes away as soon as you let up on the gas and get back on it. Currently there is no CEL on her car resulting from this.
Newbie
Joined: Nov 2021
Posts: 1
Likes: 0
2018 c300 AMG SPORT PACKAGE
2018 c300 knocking sound no check engine
Can you take a video so I can hear some audio of the sound? Most modern direct injection engines do have a very constant ticking, like a sewing machine during idle. The ticking is from the high pressure injectors. Your engine is designed to run on premium, but if lower octane is detected, the car's ECU will go into knock protection mode, lowering power output to prevent detonation. If you are experiencing detonation your CEL will go on.
Newbie
Joined: Jun 2023
Posts: 1
Likes: 0
From: Maine
CLA 250 ALL 4
Same issue!
Hi there, I've been having a very similar issue with my 2014 CLA250. I've taken it to a mechanic I've trusted for years and they didn't seem very concerned and didn't hear what I was referring to but I'm up tight about my car and would prefer it last forever. Wondering if you've found the culprit? Appreciate any feedback! Thanks!
