1986 420 sel with no cold starting. Cranks like hell but no fire. I have a new OVP, Ignition wires, plugs cap, rotor. Cold start valve is spraying upon cranking of the engine. New temp sensor as well.
Car will start when temp is in the high 20's - 30's but not when colder.
Any ideas really welcomed

shoot from the hip, sounds like the coil is too weak. the colder the temp, the higher the voltage requirement. good luck, chuck.

After checking and diagnosing every component of the cold start circuit and adjoining components, I reluctantly replaced my coil with a spare and ...VIOLA! 100% super easy starting in zero degree temps.
Just goes to show that these coils do indeed go bad...not necessarily all at once. Again, the symptoms were no starting in cold temps, absolutley fine in warm/hot.
Many thanks to Porkface....I was stubbornly reluctant to check the coil, as they "never give trouble". BTW, there was very little help offered (one post, in fact) on the subject.

Great call, Chuck! This shows how helpful these boards are, especially this one with all the knowledgeable help. Sorry about the lack of support here, GDJ, but I wouldn't have been any help as I was guessing fuel mixture rather than ignition.

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1983 380SL
1995 C280
1995 S500 coupe
1990 Mazda Miata
2004 Suzuki Hayabusa

a cold start is a great stress on any part of the ignition system. hell, even a weak speed sensor will not generate enough ac voltage to fire the ezl unit. now, would i shoot from the hip on a car i can see? nope, test, test, test. got lucky today. glad to help, chuck.