Good afternoon everyone,

Here is my situation:

Last winter I left my 1998 Volvo S70 unplugged during the -25 degree cold weather and when I went out to start the car, it did not start. Even boosting it never made a difference. 5 days later with the help of a Calgary chinook of +3 degrees and the car started immediately.

Since then, I plug in [block heater] my car when it gets below -15 degrees and have not had a problem until this past weekend. This past weekend it was -25 (and major windchill too) and 2 days later with the car plugged in it did not start at all. I put the car in a heated shop for 2 hours and then it started immediately?

Is there a temperature sensor not functioning correctly causing the mismixture of air/fuel when trying to start in the cold weather? Is it something else?

Any information is greatly appreciated.

Thanks,
Darcy

You might have something else failing...like the starter! It may have an open on the pull-in winding but is only affected during the very cold.

When it is cold out, the starter cranks well and the engine even fires briefly, but the car just doesn't catch enough to start. The Compression was tested at over 125 psi, battery over 500 cca, confirmed spark too. In nice weather the car starts and runs perfectly.

Ah ok, shoulda asked more questions. Possible fuel line freezing? or poor plugs?

I agree with Andy and would look at ignition, plugs, cap, rotor and even plug wires.
Sounds like spark may be weak and causing engine to flood

Great information..I have changed the plugs last summer and have gas line/premium 94 octane in the tank. There is a possibility that the gas line freezes up. Thinking from a spark perspective, how do I test to see if the cap/rotor or plug wires need replacing?

How many miles on the engine and have you ever replaced the cap, rotor & wires?

The car had 175,000 km on it when I bought it 2 years ago and now it has 225,000 km. The cap/rotor/wires have not been changed since purchased.

you can take the cap and rotor off and check for corrosion between the terminals inside.

I am thinking on changing the cap/rotor/plug wires proactively and leaving the spark plugs as they were recently changed.

I have 2 questions:
#1 - Does the procedure to change the cap/rotor/plug wires require any special tools or knowledge?
#2 - If it is not the cap/rotor/plug wires causing my car not to start in the cold, could it be anything else?

Could be some moisture in the intercooler, we usually drill a small hole (I mean very small) in the bottom of an endtank to allow for water to drain.
You can check the date stamp on the plug wires, it will be white or yellow writing with a year and month ex. 98.03, I had a car today with wires that are 10 years old, cap and rotor are gummed up and the plugs are nasty. Cylinder 4 plug wire had higher resistance so it wasn't starting.