Hello, I have a 1991 420SEL with 117,000 miles on it. It always has a rough start up- most of the time two attempts to start. The car runs a little rough for about 45 seconds, then (my opinion) idles a little low at 500rpm. I've noticed now that it's a little warmer outside, it starts somewhat easier- but still room for improvement. Also, the other day I was driving along about 20 mph and noticed a slight surging or lurching feel- like fuel delivery was a little inconsistent or something. After driving slowly for a bit, I then aggressively accelerated to about 65mph. While accelerating, it "missed" twice. Could this be the idle control valve? fuel pressure regulator? Simple tune-up?
Thanks in advance for your time- any help is greatly appreciated!
John.

 

Hi John,

Try Clean up you idler, if it still do rough start up ... you got an idler faulty . plus clean up your throttle body using Throttle body cleaner.. cleans out your internal parts in your engine.. and let those small vibrations go away + restore the power of your engine back. Looking at that mileage you need to do em

Good luck John

Ali