My 98 320ml with 117K is experiencing a shaking at idle, but not while the gear is in Park. The engine had recent O2 sensors replaced and a EGR valve that was cleaned out due to carbon deposits. There is no engine light that comes on. The car feels like it's going to quit in idle, when giving it a little gas, it would be fine. It seems to accelerate well. There was a previous post with similar symptoms about a coil that went bad.

What are the possible problems with this? Thanks in advance.

John

98 320ml
86 420sel

When I was told I needed a new EGR Valve by the dealer ($250)
I first thought I would remove the EGR Tube and check it.
Sure enough it was plugged. I cleaned it then my rough idle was cured and my check engine light went off several miles later.

__________________
Steve Danville
what i did myself.
CPS
rear shocks
MAS x 3.
SparkPlugs (twice)
Fuel pump & Filter
Window switch
replaced both failed horns with Honda horns.
Cleaned ERG Tube
Oil changes
Oil consumption Fix
Brake Pads
A/C Recharge
Anti-Freeze change X 2.
Front Shocks. Monroe. $90
Mercedes Warrenty Work:
Harmonic balancer,power steering clamp. Cat converters.Drive Shaft Bearing.s
Replaced Outer Lower Tie Rods and front lower ball joints at 156,000 miles

The EGR valve was cleaned about 3 months ago. Anything else?

John

Yes
the TUBE
the EGR valve needs to pass gas from itself thru the EGR TUBE to the rocker cover or intake manifold..I forget.

They should have Cleaned the tube along with the valve, but I dont know.

Outside of that, there are many more gifted mechanic's here than I that may have suggestions.

__________________
Steve Danville
what i did myself.
CPS
rear shocks
MAS x 3.
SparkPlugs (twice)
Fuel pump & Filter
Window switch
replaced both failed horns with Honda horns.
Cleaned ERG Tube
Oil changes
Oil consumption Fix
Brake Pads
A/C Recharge
Anti-Freeze change X 2.
Front Shocks. Monroe. $90
Mercedes Warrenty Work:
Harmonic balancer,power steering clamp. Cat converters.Drive Shaft Bearing.s
Replaced Outer Lower Tie Rods and front lower ball joints at 156,000 miles

OH. I got it. I think the mechanic cleaned this tube also. So can it be the valve itself?

John

yes if the valve isnt opening and shutting its not working.
In fact my dealer never offered to clean my EGR Valve. He intended to replace it.
I ran a couple bottles of gumout emmission control cleaner in my gas. Then marvil mystery oil in my gas and it seemed to help.
In you case the ERG valve was cleaned already. The Mirvel mystery oil may lubericate it and free it up. It sure is worth the $3.
to try.

__________________
Steve Danville
what i did myself.
CPS
rear shocks
MAS x 3.
SparkPlugs (twice)
Fuel pump & Filter
Window switch
replaced both failed horns with Honda horns.
Cleaned ERG Tube
Oil changes
Oil consumption Fix
Brake Pads
A/C Recharge
Anti-Freeze change X 2.
Front Shocks. Monroe. $90
Mercedes Warrenty Work:
Harmonic balancer,power steering clamp. Cat converters.Drive Shaft Bearing.s
Replaced Outer Lower Tie Rods and front lower ball joints at 156,000 miles

Where is the EGR Valve located?

rear of the engine near the firewall a bit more towards the passanger side. with a silver tbe running from it to the engine. you may want a mirror to see it. thats how i saw mine the 1st time.

__________________
Steve Danville
what i did myself.
CPS
rear shocks
MAS x 3.
SparkPlugs (twice)
Fuel pump & Filter
Window switch
replaced both failed horns with Honda horns.
Cleaned ERG Tube
Oil changes
Oil consumption Fix
Brake Pads
A/C Recharge
Anti-Freeze change X 2.
Front Shocks. Monroe. $90
Mercedes Warrenty Work:
Harmonic balancer,power steering clamp. Cat converters.Drive Shaft Bearing.s
Replaced Outer Lower Tie Rods and front lower ball joints at 156,000 miles