Hi guys, I am looking for similar topics but can't find any... Here is my problem on 1994 e320 sedan.

Very often after driving for some time and after engine warms up I have very unstable RPM. It drops and goes up. When I stop at red light RPM drops to 500 and then instantly goes to 2000 and sometimes 2500. And it keeps doing it. Sometimes shutting off engine and restarting the car would take care of this problem and engine would be stable, but sometimes not. When I drive the car on low speeds it almost never happens but it happens very often after let's say I exit the freeway. Also seems like if the car is uphill or downhill it makes it worse but I am not sure, might be a coinsidence. NO CHECK ENGINE LIGHT IS ON.

Can you guys help me out please? MANY MANY MANY THANKS!!!

 

Got car diagnosed at Mercedes... Turned out bad Mass Airflow Sensor. Would cost $650.00 to replace at dealership, pasrt is $450.00 however this sensor on ebay is $70.00 brand new one. Posting this just in case someone has similar problem. I will actually try to clean the sensor and see what happens.

 

Beware of "eBay" MAF [air mass sensor units]. A search of on-line fora will give you a long list of horror storiesaboutthis...

Get the OE Bosch unit and you will be good to go. Get an "eBay" unit and you will most likely end up buying the OE unit anyway, you will just be out the $70.00 you paid for the "eBay" part.

You do not have to buy the part at the dealer; Autohaus Arizona or GermanStar have them at a reduced cost.

Good luck,

JR

 

Usually with those stmptoms it is the maf or a vac leak.Clean the maf with crc brand maf cleaner.Do not rub the wires only use a spray.
http://www.autohausaz.com/search/pro...0Mass%20Sensor
brand new oem maf
never get maf's off ebay they are almost all chinese clones or reconditioned usded ones.
ohlord
inspect your wire harness while you are in there