I'm woking on a friends 1990 300 TE wagon , that has a cold starting problem.

It's been really cold here in Buffalo, (9 deg f) and when you try to start the car, it sputters a bit then dies. I've done this continually, and it won't start outside.

I moved it indoors overnight (50 deg garage) and it started, but in the same manner, misfiring, idiling at 500 rpm (smoothly though?!), backfiring through the airfilter, sluggish up until 2-3000 RPM. When it warms up, it's better.

I'm not too familiar with these cars, and did a search. I came up with an OVP relay (what does that do?)

how do I pull the codes>?
what else should I look for?
there is also a plug at the rear of the engine looks larger than a temp sensor- has four wires coming to it, and has a sheiled boot, like a spark plug boot, but smaller- can anyone tell me what that is/does?

thanks for all your help!

Percy.

First: plugs (the right kind), distributor cap, rotor, spark plug wires.
Then
Cold start valve, temperature sensor, fuel pressure, coil,

The four pin sensor is the temp sensor for fuel management and EZL (ign).
There are two seperate sensors inside,Unplug the connector and turn it 1/4 turn and reinstall, This will put the other sensor to the fuel manaagement.
The OVP is a good possibility as there would be no cold start valve actuation,idle-up or fuel enrichment if it were bad.
If you are not already using regular grade gasoline then switch now for cold weather.
Find out if this car has oil consumption history, If it has worn guides and seals it will be hard to start.
Mike