W204 c63 idle

[calb94]

Noticing the car has a bit of a rough idle, the needle on the Speedo doesn't budge but can feel a bit of a vibration when at a stop, is this normal or should I go get it checked out? Cheers

 

[Jobsworth]

Same in drive and reverse/neutral, or worse in drive? Engine/gearbox mountings if so

If the idle is fluffy all the time they are common for vacuum leaks too

 

[AMGeed]

How are your engine mountings? Worn mounts will give the vibration feeling when stopped.

How many miles have you done with current spark plugs? Should be changed every 4 years/60k miles.
Start the car with the bonnet raised once its dark and look for any arcing from the coil packs/leads.

 

[calb94]

Same in drive and reverse/neutral, or worse in drive? Engine/gearbox mountings if so

If the idle is fluffy all the time they are common for vacuum leaks too

It's the same in drive etc

 

[calb94]

How are your engine mountings? Worn mounts will give the vibration feeling when stopped.

How many miles have you done with current spark plugs? Should be changed every 4 years/60k miles.
Start the car with the bonnet raised once its dark and look for any arcing from the coil packs/leads.

It's coming up to 60k on the clock but I think they've been done before, should I replace anyway?

 

[AMGeed]

It's coming up to 60k on the clock but I think they've been done before, should I replace anyway?

Depends when they were last done really. I wouldn't rule out a fouled plug which would be fixed with a plug change.
Is the car stock or remapped? If its been remapped, the spark plugs should be changed more frequently than the recommended intervals.

My last car, an E55 had the plugs changed and even though I thought the old ones were fine, the difference in the smoothness of the engine was noticable. Only 8 plugs to change on the C63 as well

 

[calb94]

Depends when they were last done really. I wouldn't rule out a fouled plug which would be fixed with a plug change.
Is the car stock or remapped? If its been remapped, the spark plugs should be changed more frequently than the recommended intervals.

My last car, an E55 had the plugs changed and even though I thought the old ones were fine, the difference in the smoothness of the engine was noticable. Only 8 plugs to change on the C63 as well

As far as I'm aware it's stock but it's had a few owners before me so not really sure, I'll get them done and see if it changes it if not I'll check engine mounts cheers

 

[jasonh]

You might be over analysing the situation. It is a huge V8 in a fairly high state of tune idling as low as it can. It won't be as smooth as a small capacity 6 cylinder or even a small 4 cylinder.

I can feel my idle but the emissions test show the engine is running absolutely perfectly.

 

[calb94]

You might be over analysing the situation. It is a huge V8 in a fairly high state of tune idling as low as it can. It won't be as smooth as a small capacity 6 cylinder or even a small 4 cylinder.

I can feel my idle but the emissions test show the engine is running absolutely perfectly.

That is a possibility, maybe it's just me over thinking it I'll try get a video of it but might be hard to show on a video

 

[jasonh]

A local MOT station could very quickly run an MOT emissions test, that's run at "Natural Idle" and "Fast Idle", this will tell you if the engine is running correctly.

Diagnostics should tell you if there are any faults.

If that's all clear then you're down to engine mounts or that's just how they idle.

 

[calb94]

A local MOT station could very quickly run an MOT emissions test, that's run at "Natural Idle" and "Fast Idle", this will tell you if the engine is running correctly.

Diagnostics should tell you if there are any faults.

If that's all clear then you're down to engine mounts or that's just how they idle.

Thanks I'll get it into the garage

 

[jasonh]

MOT bays are pretty empty at the moment!