mercedes c220

[alan5767]

could anybody please help.i have a 1996 n reg c220 petrol
when the car is warm it surges every now and again ie the revs go up and down on their own also when stoped in drive it will cut out but only now and again.and you can not rev it over 4000 revs it is like it has a rev limiter on it.it ticks over about 7500 revs and it feel's like it has a very slight miss,
hope some one can help thankyou

 

[Bigtee]

Check for air leaks like vacuum pipe dropped off, & give the throttle body a clean with carb cleaner.

Any slugde on the butterfly wants cleaning off.

 

[C220GJS]

Also check that all the throttle return springs are in place, there is one about 3" long which goes from the throttle spindle crank vertically down to a hole in the mounting plate,it regularly breaks and drops off unnoticed;77 in the first diagram http://www.detali.ru/cat/oem_mb2.as...GM=717.417&CT=M&cat=19K&SID=07&SGR=160&SGN=03 ;it's function is to pull the throttle back onto the idle microswitch,so obviously will cause problems with idling if it is missing.
Regarding the rev limiter,it stops the engine revving above 4000 in N or P for safety reasons.