Hi gang...</P>


Picked up 1986 420 SEL w/245000 miles <IMG src=smileys/smiley3.gif border="0"> has starting problem and when it does start it goes into this nasty skipping and miss firing mode when it warms up. I'm in Connecticut and we're having very cold weather, I moved the car into a semi heated garage and change the plugs, rotor, cap, plug wires (all were very bad) put fresh gas in and some fuel injection cleaner. Car ran good for a while but started that same problem again??? I'm thinking fuel system? water in the gas? dirty fuel injection system? we're stumped right now looking for possible answers before we take it to a mechanic$$$$ . Going to do a cold &amp; then hot compression check next but running out of things to try. Anybody have simalar probs?</P>


Thanks.</P>


John Mik </P>

i have the same problem with mine too...only when it is cold...after that it runs fine...</P>


i think it is a sensor...!!</P>

I have an 87 420SEL w/ 143k milesand live in NYC. There has been massive cold here too but I dont have problems at all when starting. When you changed the plugs and caps, did you use platinum tipped?? If you did then that could be the problem. I heard that copper tipped plugs are better for our model benz. check the Oxygen sensor alsoAlso, try checking theh fuel filter and air filter and use some additives for the fuel system. Since your 420 does have over 220k miles,check those things out... Lastly is do you have black smoke coming from the tail pipe?? If you do check the EGR sensor/valve