Engine Trembles when car is in Par or Idle

[mercc320]

I have noticed that when the automatic car is left in park or when I stop at the lights, the engine is shaking the car. When I release the brake the car edges forward in small increments rather than smoothly as its supposed to. It drives well on the motorway or at 10 revs or higher and the power is still quite good.

Im thinking that the spark plugs need replacing or that the little computer regulating the fuel injection requires replacing.

Any ideas out there?

 

[rpe2]

Assuming from your user name that your car is a C320 petrol, try the Coil packs/ HT leads.

Getting the fault codes read by an indie may save you a lot of trial and error based expense.

If you can say where you are based, I'm sure that the forum can recommend an indie near you.

Richard

 

[mercc320]

Hi Richard, thanks for the reply.

I just got a message showing on the dash screen. It says 'undervoltage consumer defective'. The seller said that he replaced the battery recently. It may well be that there is not enough volatage getting to the spark plugs etc.

This message seems to appear when i have the fog lights and cd player on at the same time. I may try a new battery and see if that helps.

I will probably drop by the garage monday, but I was hoping to try and avoid any major expenses

 

[wireman]

When your cars engine is running the alternator provides ALL the electricity, Check the voltage at the battery it should be 13.8 to 14.4 volts (engine running).

Try adding all the extra loads you like and see if the battery terminal voltage falls as you add them, headlights, fog, A/C, and rearwindow heater all consume lots of power but your alternator should be able to keep at least 13.8 v with all of them on and the engine at only a little above tickover speed.

If the voltage falls with load it would be the alternator brushes that I would tackle first.

 

[mercc320]

Thanks for the advice. I will take the car later today to get the thing read by my local garage. Hopefully nothing will be wrong with the sparks