What to do when your car won’t start in cold weather
Diagnose car won’t start in cold weather
Diagnosing a car won’t start in cold weather condition is similar to diagnosing any other type of car won’t start condition. In other words, start with the basics: fuel and fire.
How to test for spark
If your engine uses spark plug wires, check for spark by removing one of the spark plug wires from a plug and hold it about a half-inch away from the top of the plug while someone cranks the engine. You should hear a sharp cracking noise as the spark jumps the gap to the spark plug.
If you can’t get the spark to jump the gap, you may need a tester. Here are three types:
Lisle 20610 inline spark plug tester
Install the Lisle 20610 inline spark tester between the spark
plug wire and the spark plug. Then crank the engine and watch the spark jump across the gap in the window area
Lisle 19380 Spark Tester
Slide the grooved portion of the tester over a spark plug wire
and crank the engine. The Lisle 19380 Spark Tester includes an inductive pickup that lights a neon tube inside the tester every time it detects high voltage discharge.
Test coil-on-plug ignition system
If your car has a coil on plug ignition, you’ll need a special tester to see if the coil is firing. Waekon-76562 Quick Variable Sensitivity ignition coil tester is designed to give a visual indication every time a coil on plug coil fires. Just hold the sensor end on the coil and watch for the visual indication.
You’ll also need a special tool to check for fuel injector firing. The Waekon 76462 Universal Electronic fuel injector tester works just like a coil tester. Simply place the probe on the injector and it lights up when the injector fires.
If the coil and fuel injectors fire
If the ignition coil and fuel injector fire, you should get combustion and engine fire up.
But there are other issues that can cause a car won’t start in cold weather. Let’s talk about those.
Is the engine cranking at the right speed?
Motor oil thickens when cold, causing more friction and reducing engine cranking speed. But cold weather also reduces the chemical reaction inside the battery, lowering its voltage and amperage output. In addition, corrosion on the battery posts and terminals can dramatically lower the power available to the starter.
If your engine isn’t cranking at the proper speed, it won’t start even if it has spark and fuel. An internal combustion engine requires at least 100 RPM to start. If your engine is cranking slowly, check the battery charge level using a digital multimeter.
Check battery voltage
These are the voltage reading for a maintenance-free battery at various charge levels and temperatures.
Battery voltage at 50°F
Fully charged 12.77 volts, 50% charged 12.37 volts, 25% charged 11.97 volts, 0% charged 11.77 volts
Battery voltage at 20°F
Fully charged 12.56 volts, 50% charged 12.15 volts, 25% charged 12.032 volts, 0% charged 11.80 volts
Battery voltage at 0°F
Fully charged 12.66 volts, 50% charged 12.26 volts, 25% charged 11.86 volts, 0% charged 11.66 volts
If your battery voltage is at 25% charge or lower, it’s probably not providing enough power to crank the engine at a fast enough speed to start. Charge the battery or buy a new one.
©, 2018 Rick Muscoplat
Posted on by Rick Muscoplat