Y2KML55

My friend has a 1994 E320 with 128k miles on it. The car has started to run poorly. The idle is dropping to 500rpm and then racing to 1000-1200rpm and then drops to 750 after a short period. The idle is very rough. Slow acceleration is normal but the car feels like it is missing on kickdown. Light black smoke is evident when the car is running rough. This issue is hit and miss. It happens at cold start up sometimes and can happen after the car is warm and has been driven. The issue does not happen every time the car is driven.

Any possibilities???

Kestas

Is the engine wiring harness original? A lot of savvy mechanics won't touch a 94 E320 unless the engine wiring harness has been replaced.

Y2KML55

I do not know if the harness is origional or not. I do know that heis the second owner and the car had an excellent service history.

Kestas

You can probably tell by looking at the present wiring. Remove some of the black tape and look at the wiring insulation. If it's cracked and flaking, it's probably the original wiring and needs to be replaced. There's a very good chance this is the problem.

Do a search using "engine wiring harness" for more information on this subject.

Daniel_uk

If i was you i check teh spark plugs the same time. Compare the looks between the cylinders.

Wiring harnest is proably the reason, as you where adviced earlier. Check that first.

Daniel

Y2KML55

W124 does not like platinum plugs! It needed an R0 rated plug. Thanks.

Goat17

HI,
I have a 1993 E220 Sedan that is having similar issues to your vehicle. Have you solved the problem? My service agent is advising me to change the computer, but will not guarantee that this will fix the problem. Hope you can help.
Patrick

jsolano

I had a similar problem, and it turned out to be the air mass flow sensor.

higgins

I agree that is most likely the problem. Will cost between 3 and 5 hundred dollars to replace, very expensive part.........shop around.........Hig

Goat17

Thanks for the advice, however I have already changed the air mass flow metre and the errors still remained. Thankfully they took it back. Where to from here?

Kestas

Unfortunately, it could be a bad throttle actuator. These suffer from the same crumbling wire disease that the engine wiring harness suffers. Cost for replacement is over $1000 USD for this part.