My 500E is quite low on power and I am beginning to think there is something wrong with the engine. I've not had the codes read yet but the PO is a friend of mine (owned it for 8 years) and he said it was not producing near enough power compared to when he owned it. He now owns an E500, I've not driven his E500 for a while but seem to recall it is much quicker when I did a few months back. My E55 is a bullet in comparison but the M113 does have different character.
There are no obvious mechanical issues other than I did have a rattle at cold start a few times. That seems to have gone away weirdly enough with no engine work done other than the rocker covers replaced.
Hoping to take the car in tomorrow for a read of the codes and a compression test on each of the cylinders to rule out anything sinister. Any recommendations or areas to check while the car is in? I have replaced the MAF to a used but remanufactured unit and also the throttle body is dated 1997. I have not dropped the oil pan to check for guides. How about chain stretch? Again never really heard of them going bad. PO suggested the rattle is probably the chain tensioner.
I have not replaced spark plugs or any of the ignition parts yet - plugs, distributor caps and rotor arms were changed around 1.5 years ago. Wires probably 3-4 years ago. Ignition coils never replaced in the last 10 or so years. Would ignition issues show up on diagnostics?