RPB

My 500 recently has been idling a little rough at lights, occasional delay in throttle response, bad gas mileage, and odd exhaust smell. Very low mileage car and well maintained. No cel light. Could be bad O2 Sensor, but thought it would usually trigger a cel, so not too sure. Car seems to be running too rich. Any ideas? Thx!

shenagles

maybe the cat?

RPB

Hope not, no issue w/acceleration and car recently had stringent emissions inspection done. I say bad gas mileage but I am getting about 15-17mgp, so I think avg for the 500. Never replaced MB cat before and own a few with high mileage, orig cats.

AMG140.6

Sounds like you need a distributor cap and rotor kit, also might want to check the EZL unit.

If those 2 are ok, then have a look at the throttle body unit. They go bad, but can be rebuilt. Too expensive to buy a new OEM one.

Search the web for W124 500e throttle body rebuild and you'll get a link for the place that does them.

Exhaust smell might be from leaking VC gaskets ? 17mpg isn't great for the M119 motor but not that bad either....the norm is 18-20 mpg hwy.

HTH

Jim's500E

The odd smell of the exhaust would point to a bad/clogged cat in my mind...what sort of mileage is on your car? They have and do go bad. Crawl under there and wack it with a rubber mallet and listen to see if there are pieces loose.

I happen to have a good used M119 TA for sale btw if it is that, but I doubt it is.

larryj

To determine if it IS the converters, and if you have an O2 Sensor between the cats and the engine, just remove the O2 sensor and see if that helps your situation. If so, it's the cats.

RPB

Took it to my mechanic who worships my 500, he took nearly two hours of his personal time running all sorts of tests and thought I was loosing my mind! He said the car is sound, but did mention that the ignition wires were orig and that the sparks were recently changed around 56.5k @ the 60k svc. I have heard that the M119 is picky when it comes to sparks, so I might look into this more. He also mentioned that the petrol in the US does not help out and I usually run Exxon or Shell 93.

JSe420

Well you can certainly rule out bad VC gaskets because there is no way that would give you an exhaust smell.

I had a similar problem going on with my 420 and it ended up being a fuel pressure regulator so check that out. You could also have a problem with your electronic throttle actuator as someone already mentioned.

Carbooks

Sounds like the dreaded engine wiring harness to me.

Kind Regards,

Ron