Jayrice

Help! Just started bucking like a bronco in the last month. Only intermittently at first, so did full tune-up and changed vacuum line off of engine block. Now when I accelerate at all, it will buck and jerk until I hit around 45-50 mph. Mass air flow sensor or wiring harness?

barry S320V

I REPLACED THE SPARK PLUG COILS TO FIX POOR/ROUGH RUNNING.

MrSaratoga

I also have a '96 S420 with same issue. When I unplug the MAF, the problem seems to go away. The car doesn't run REAL good with it unplugged, but the bucking goes away. I ordered a new one off eBay and will put it in to see what happens. If you get yours fixed, please let us know what the solutions was (I will do the same likewise) Good luck!

BookW140

I have a "94" S420 that does the same. I did caps and rotors also I cleaned the MAF but still does it. How do you check if this is bad???Could this be fuel filter related???

CIGAR_LOUNGE

Clean FUEL system , and use highest quality FUEL,,,,,

see the differance

M

AMBUSHED

JUST HAD SAME PROBLEM, ENGINE WOULD SURGE LIKE YOU WERE REVING ENGINE, WHILE CHECKING THE MAFS WHICH WAS LOOSE. I FOUND A WIRE BEHIND THE MASF THAT WAS LOOSE . WHILE MOVING THAT WIRE TO THE LEFT ,THE PROBLEM WAS GONE .WILL FIND OUT WHAT THAT WIRE IS AND LET YOU KNOW.

oldsinner111

mine does that now do to me using a fuel system cleaner.I figure it clean trash in the tank,and now filter is clogged.or fuel cleaner thrashed the fuel pump.I ordered new filter,and I'm awaiting clamps.Ma Benz crimped hoses on,so you have to cut crimp then use special hose clamps..

AMBUSHED

SOUNDS LIKE THE ETA (ELECTRONIC THROTTLE ACTUATOR) THE WIRING COVERING HAS CRACKED AND SHORTED. CHECK VICTORS WEBSITE RESTOREYOURMERCEDES.COM