Hi, I live in the UK and have a yr2000 ML320 with about 80,000 miles, sorry for the long post but a bit of background info may be helpful for someone to suggest ideas - Over the past year the truck has become pretty "sluggish" especially noticable when it faces any hills (speed drops doesnt matter what you do with the accelerator). Adding to this from cold I now have to start the truck (starts first time everytime! and always has) and let it idle for about 2 mins before putting it into drive, if I select D straight after starting and try to drive off it judders, hesitates and is totally undriveable - only way to get it back into action from this point is to turn the ignition off and back on again - as I dont use the truck everyday I've learned to live with the above (at this point the engine light has never been on once)....
However things have just got a whole lot worse - I'd not used the truck for a week or two so thought I'd take the battery off and give it a charge, put the battery back on the next day and O NO, truck starts first turn of the key but then revs drop down to 400-500 where it sounds like its running on 1/2 the cylinders and it either stalls or idles at very low revs (occasionally jumping up to 1,500 revs on its own before going back down) touching the accelerator doesnt seem to have much effect, other than stalling it sometimes. Engine light is now on so read the codes and initially it had P0300, P0304, P0305, P0306 if i'm right thats the 3 cylinders on the right looking from the front? with misfires, no other codes also what I can hear is what sounds like a "stone" rattling around in the cat area of the exhaust on that side (this rattling has been around for a while - not just since the battery was removed/charged), not sure if this is related in any way?. Cleared the codes and restarted a couple of time and codes still read pretty similar P0300, 304 and 305 now. I dont use the truck all the time and not in a position to spend £££'s on it at the dealers, any advise would be more than appreciated, if you've not fell asleep reading all that !!, sorry
Couple of other things, air filter, spark plugs, oil changed about 8 months back but initial problems were apparent before and after that point
However things have just got a whole lot worse - I'd not used the truck for a week or two so thought I'd take the battery off and give it a charge, put the battery back on the next day and O NO, truck starts first turn of the key but then revs drop down to 400-500 where it sounds like its running on 1/2 the cylinders and it either stalls or idles at very low revs (occasionally jumping up to 1,500 revs on its own before going back down) touching the accelerator doesnt seem to have much effect, other than stalling it sometimes. Engine light is now on so read the codes and initially it had P0300, P0304, P0305, P0306 if i'm right thats the 3 cylinders on the right looking from the front? with misfires, no other codes also what I can hear is what sounds like a "stone" rattling around in the cat area of the exhaust on that side (this rattling has been around for a while - not just since the battery was removed/charged), not sure if this is related in any way?. Cleared the codes and restarted a couple of time and codes still read pretty similar P0300, 304 and 305 now. I dont use the truck all the time and not in a position to spend £££'s on it at the dealers, any advise would be more than appreciated, if you've not fell asleep reading all that !!, sorry
Couple of other things, air filter, spark plugs, oil changed about 8 months back but initial problems were apparent before and after that point