rough running until warmed up

[south280]

Hi, My 1968 280sl 4-speed manual runs rough until the engine is warmed up and driving for a while then it runs great.  When I first start driving, it hesitates and almost bucks?   thank you in advance for any advice  Thanks 

[Nicolas Aristodemou]

I would suggest you do the linkage tour as described in the technical manual which includes the procedure to adjust the idle mixture of the fuel injection pump. Check also ignition timing. If problem persists you should check the condition/operation of your CSV (cold start valve) - again procedure detailed in technical manual.

[Cees Klumper]

In addition to Nicolas' suggestions, I recommend checking the information here on the engine warm-up cycle, more specifically the role of the Warm Running Device (WRD) that's on top of the fuel injection pump. Many, including myself, have had to check its operation and make adjustments (adding or removing round and oval shims that govern the time and extent of fuel enrichment during warm-up - an automatic choke of sorts).

[ja17]

If your lucky it might just be a plugged air filter on your WRD. Check it first, if it is plugged it can cause your symptoms. It is the little round canister at the side of the WRD. You might not have to take it off to check it. If you can hear air rushing into it during warm up it is probably not be plugged. Use a rubber hose (like a stethoscope) place it on the intake side of the filter to hear. If the rushing air sound goes away after engine warm-up, your WRD is probably functioning, but could need adjusted.

[wayne R]

If your car is  rich, over time ,your spark plugs can get slightly fouled of damp,
this happens alot if ---i see you have  4 classics---  if you have them all in same garage and you start
the engine  in Pagoda and idle cold, while moving another classic to get the Pagoda out  of garage,
this is not good if your car is running rich ,place Pagoda in front so you can drive straight out.