96 S320 Mercedes Engine Shakes

[NMB]

My 96 S320 Engine shakes uncontrollably at times. It usually starts when I am driving and it does not matter the speed. Once I pull over I can see the front end of the car shaking. But once I turn the car off and turn it back on it stops. What is this? I was thinking that I need new motor mounts but thought it could be something different, since it goes away once I restart the car. Can anyone help????

 

[marshie001]

it sounds to me as if one or more of your cylinders are not firing! check and maybe replace your plugs, leads and dizzy cap.

 

[jberks]

The intermittent shake is a common misfire characteristic, especially if yours is a twin spark. (Doesn't feel like a typical misfire as you still get a spark from the other plug, but the cylinder will be down on power and hence out of balance) As above, usual suspects, though you may not have a dizzy cap.
Could also be more sinister with ECU etc (restart resets it). Lets hope not.

 

[jonathanjhann]

on the 320 engines the leads are the usual cause of miss fires due to the carbon in the lead breaking down. Best to replace all the leads, expensive but easier than trying to diagnose the rogue ones!

 

[NMB]

What are leads?????

Thanks

 

[OlafMaxwell]

Spark plug leads, one for every spark plug. I presume that means 12 of them. Whileyou can probably get alternatives to Merc do get good ones, try some of the suppliers in Mercedes Enthusiast, at least then they will have the right fittings and be the right length. Best to replace them one at a time so you dont get the order/sequence mixed up!! Saves having to go look for the sequence too.

 

[jonathanjhann]

If you look at the engine with the cover off you will see 3 ignition coils per side, each will have two leads coming from it. The top output of each coil goes to the most forward plug of each pair and ones at the rearmost and furthest forward are longer than those in the middle.
Therefore, if you unbolt each coil you should be able to replace all the leads on a side and refit them correctly.

 

[rsranny11]

if your car is fitted with a mass air meter sensor then change this .

 

[television]

if your car is fitted with a mass air meter sensor then change this .

This post is 4½ years old,,I wonder if the op is still working on it