Hard to start when cold — what to look at
The check takes one morning and halves the list of suspects.
Connect BEFORE the first start
All the value is in the first seconds. Plug the adapter into a cold car, open the live data, and only then turn the key. Once warm, half the signs disappear.
Check what the temperature reads before starting
On a car left overnight the coolant temperature must match the air outside. Reading 40 °C on a frosty morning means the sensor lies and the unit prepares a mixture for a warm engine. This is one of the most common causes of a hard cold start.
Start it and watch the revs for the first half-minute
A healthy car lifts idle to 1100-1500 straight away and lowers it smoothly as it warms. If the lift never happens or the revs sag towards stalling, look at air supply and the crank sensor.
Look for misfires that appear only when cold
Plugs and coils often fail only on a cold engine: condensation, different resistance. Misfires that vanish after five minutes of warm-up are not a «random fault» — they are a hint about where to look.
Save the cold-start log
You cannot repeat such a morning on demand: tomorrow may be warmer. A recorded cold-start run is worth more than a retelling from memory, and you can hand it to a mechanic as it is.