So i have a misfire in my 420. The car runs and drives perfect when up to speed on the road, but when i come to a stop, it skips pretty bad, sometimes even surging. It also starts real rough when cold. So far i've replaced; Plugs, wires, distributors, and rotors. Also, i have inspected my wire harness and its in good condition. Could this be a problem with one of my coils? Any help is appreciated

 

anybody?

 

Alright. Lets see.
What plugs?

 

8 Spark plugs... but it was doing this even before the change of the spark plugs and ignition wires.

 

Hrm. What specific model spark plugs? We can not use resistor plugs in our cars and the proper gapping on the plug is VERY important.

Have you changed/checked the thermostat?

 

Funny you should ask i have had a new therm. kit in my back seat for like a month i just havent gotten around to doing it yet. But that wouldnt be my problem....or would it??

 

Probably not, but it may need doing anyway. I found that when my therm was bad my car ran much much nicer. It was running on the warmup mix constantly as the engine never got over 80C or so :P

Gimme the stats on your plugs sir, I am suspecting them.

 

i know what your gunna say about my bosch plugs lol. But honestly, we use bosch plugs daily at my shop and we have never had a problem with them. Ignition wires are another story...

Im suspecting a coil that could be on its way out because the car runs perfect when rpms are over 1200.

 

Bosch are fine so long as they are not Platinums and not resistor plugs. They also need to be gapped properly. Please provide the plug model :P

 

they are long gone, i threw all the old boxes out and have since made a dump run I will have to pull one out. But if it was the plugs it would have more of a constant skip even at higher rpms.