I have an unusual 'wobble' on my 500SL engine between just over 2000rpm to just under 3000rpm. I've not been too precise because the engine speed at which it occurs varies but always with that range. It has done 94,000mls with good history and regular servicing.
The idle is fine, smooth and the control valve responds to drive / neutral changes. But as you slowly lift the rpm the engine begins to 'wobble'. There is the slightest hint of an uneven firing from the exhaust - doesn't even amount to a misfire just an uneveness in the 'beat' of the exhaust. As you continue to raise the rpm it clears and returns to nice smooth running.
The car has done this since I bought it last spring. I have replaced plugs, air filter, distributor caps and rotor arms. It has had 2 treatments of quality fuel system cleaner.
The old plugs were perfect and consistent, the car performs very well although it struggled to meet the emissions test.
I've run out of ideas - any suggestions.
The idle is fine, smooth and the control valve responds to drive / neutral changes. But as you slowly lift the rpm the engine begins to 'wobble'. There is the slightest hint of an uneven firing from the exhaust - doesn't even amount to a misfire just an uneveness in the 'beat' of the exhaust. As you continue to raise the rpm it clears and returns to nice smooth running.
The car has done this since I bought it last spring. I have replaced plugs, air filter, distributor caps and rotor arms. It has had 2 treatments of quality fuel system cleaner.
The old plugs were perfect and consistent, the car performs very well although it struggled to meet the emissions test.
I've run out of ideas - any suggestions.
