w220 m112 shaking engine

Feb 20, 2023 | 08:19 AM

khalidabdu

Thread Starter

Newbie

Joined: Feb 2022

Posts: 5

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s280 w220 m112 v6

w220 m112 shaking engine

hello everybody ,

i have w220 s280 v6 2005 160,000 mileage .. the engine is shaking at idle but i have notice that when the secondary air injection works the engine becomes very stable and no shaking , but when it turns off the engine starts shaking again .. what do you think is the problem .. is it vaccuam leak or engine mounts or something else ??

Feb 20, 2023 | 10:59 AM

Fried Chicken

Super Member

Joined: Dec 2007

Posts: 980

Likes: 225

2005 S500 Designo

What happens when the engine gets warm?

Feb 20, 2023 | 02:56 PM

khalidabdu

Thread Starter

Newbie

Joined: Feb 2022

Posts: 5

Likes: 0

s280 w220 m112 v6

Quote:

Originally Posted by Fried Chicken

What happens when the engine gets warm?

the shake becomes less when the engine gets warm but doesn't disappear completely.

Feb 22, 2023 | 05:23 AM

tim687

Super Member

Joined: May 2021

Posts: 554

Likes: 150

From: Netherlands

CL 600 '00 5.8L V12

It sounds like there is too little oxygen in the exhaust, which causes the ECU to lean out the mixture. What happens when you disconnect your O2 sensors?

Feb 22, 2023 | 06:33 PM

Fried Chicken

Super Member

Joined: Dec 2007

Posts: 980

Likes: 225

2005 S500 Designo

If spark plugs and coils haven't been replaced, now might be a good time to do them.

Feb 24, 2023 | 12:54 PM

khalidabdu

Thread Starter

Newbie

Joined: Feb 2022

Posts: 5

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s280 w220 m112 v6

Quote:

Originally Posted by tim687

It sounds like there is too little oxygen in the exhaust, which causes the ECU to lean out the mixture. What happens when you disconnect your O2 sensors?

haven't tried it yet . by the way i hear hissing sound coming from the side of bank 2 of the engine .

Quote:

Originally Posted by Fried Chicken

If spark plugs and coils haven't been replaced, now might be a good time to do them.

actually i have change all sparks recently and i noticed that the tips of the sparks of the cylinder 5 were black not like the others .. !! by the way that cylinder was giving me misfire when the rpm hits 5 or 6.

Feb 24, 2023 | 08:08 PM

wallyp

MBWorld Fanatic!

Joined: Dec 2012

Posts: 2,475

Likes: 439

From: Ball Ground, GA (N of Atlanta)

2003 S500 2007 GL450

Use a 1.5m rubber or plastic 10mm tube stuck in your best ear as a locating device to find where the vacuum leak is located.

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May 14, 2023 | 07:39 PM

alex6455

Junior Member

Joined: Jan 2014

Posts: 40

Likes: 1

From: Denver, CO and Palm Beach, FL

2005 S600, 2017 Gran Turismo, 2016 LR4

I always think engine mounts (for no logical reason), but that doesn't give us any insight as to why the engine runs smoother with the secondary air injection on. Do you have any clue as to the last time the mounts were replaced?

Last edited by alex6455; May 14, 2023 at 08:08 PM. Reason: added content

May 14, 2023 | 11:48 PM

#10

Fried Chicken

Super Member

Joined: Dec 2007

Posts: 980

Likes: 225

2005 S500 Designo

The secondary air pump is a good indicator of issues. Explore O2 sensors, MAF, maybe intake manifold flap issues (I believe it plagues these engines).