157 Engine RPM Issue
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Joined: Aug 2025
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Mercedes-AMG CLS 63 S 4MATIC
157 Engine RPM Issue
Hey guys, I have a C218 2017 Mercedes-AMG CLS 63 S 4MATIC, and the reason I'm posting here is because E class owners are generally more mature and the car is more popular than the CLS, meaning more activity here.
I'm not sure if this is an issue, I personally think it shouldn't be like this, but when I start my car, and switch from P to D, and while holding the brake or just as in the video, where the car is in the air, there's RPM idling goes up and down, up and down and so on, and forever. It goes like from 500 RPM to 800-1000 RPM noticeable by ear. The car had a small accident and it did sit for 1,5 years, but before that constant oil changes at 5.000 km, only the best possible Gasoline, and so on. So far while the car was being repaired, the last 400 km or so while moving in throughout the last 2,5 years, I've changed the oil two times. Not sure why the RPM idling up and down.
Did anyone had the same experience with their engine something similar?
I'm not sure if this is an issue, I personally think it shouldn't be like this, but when I start my car, and switch from P to D, and while holding the brake or just as in the video, where the car is in the air, there's RPM idling goes up and down, up and down and so on, and forever. It goes like from 500 RPM to 800-1000 RPM noticeable by ear. The car had a small accident and it did sit for 1,5 years, but before that constant oil changes at 5.000 km, only the best possible Gasoline, and so on. So far while the car was being repaired, the last 400 km or so while moving in throughout the last 2,5 years, I've changed the oil two times. Not sure why the RPM idling up and down.
Did anyone had the same experience with their engine something similar?
MBWorld Fanatic!
Joined: May 2018
Posts: 6,609
Likes: 6,561
From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
If based on M276.8 , a 3.0TT my car engine, if you are hanging the wheels off the ground and engage D, it will do that RPM swing like your engine.
My car also has LSD, but the torsen type.
I think the engine and transmission is sensing too low a load or something , also when not in dyno mode, it will not allow you to throttle up more speed,
ABS sensor detects front and rear wheels speed difference and will apply brake.
Try it on the ground in D while in brake hold.
My car also has LSD, but the torsen type.
I think the engine and transmission is sensing too low a load or something , also when not in dyno mode, it will not allow you to throttle up more speed,
ABS sensor detects front and rear wheels speed difference and will apply brake.
Try it on the ground in D while in brake hold.
Thread Starter
Newbie
Joined: Aug 2025
Posts: 15
Likes: 1
Mercedes-AMG CLS 63 S 4MATIC
If based on M276.8 , a 3.0TT my car engine, if you are hanging the wheels off the ground and engage D, it will do that RPM swing like your engine.
My car also has LSD, but the torsen type.
I think the engine and transmission is sensing too low a load or something , also when not in dyno mode, it will not allow you to throttle up more speed,
ABS sensor detects front and rear wheels speed difference and will apply brake.
Try it on the ground in D while in brake hold.
My car also has LSD, but the torsen type.
I think the engine and transmission is sensing too low a load or something , also when not in dyno mode, it will not allow you to throttle up more speed,
ABS sensor detects front and rear wheels speed difference and will apply brake.
Try it on the ground in D while in brake hold.
Yes, while it's on the ground no RPM idling up and down, I'll check cold and warm and keep you guys updated.
MBWorld Fanatic!
Joined: Feb 2017
Posts: 2,305
Likes: 1,208
From: Baltimore County, MD
'13 s212 63 p30. '06 LX470
I checked this morning and as soon as the idle dropped after the start, it was dead straight with no variance. This was in park. This was in drive facing up a hill and drive on flat surfaces. This was all before the engine was warm.
Out Of Control!!
Joined: Apr 2019
Posts: 11,958
Likes: 6,802
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
UNSTABLE IDLE HUNTING
OP is exemplifying lean laggy idle with unstable hunting Rpm.
Idle is not too bad besides it is associated with spongy pedal response instead of rock solid.
ECU is closely matching fuel map to engine abilities. Lean lag setup is an optional choice, not a mystery.
The only way I know to regain predictable control is with stable timings. That's what ECU needs.
The unstable idle evidence the engine operation.
Idle is not too bad besides it is associated with spongy pedal response instead of rock solid.
ECU is closely matching fuel map to engine abilities. Lean lag setup is an optional choice, not a mystery.
The only way I know to regain predictable control is with stable timings. That's what ECU needs.
The unstable idle evidence the engine operation.
Last edited by CaliBenzDriver; Sep 27, 2025 at 04:01 PM.
