Opel Meriva 1.4 gasoline engine (Z14XEL) doesn't start when cold

Here's a Opel Meriva with a Z14XEL engine. It only starts after multiple attempts if it has been sitting for a few hours. If it sits overnight, you have to crank it for about 10 minutes before it will start. The error memory is clear, the fuel pressure is good at the injectors, the throttle body has already been cleaned and recalibrated, and the thermostat sensor has also been replaced. Any ideas?

Check if a speed signal is detected during startup.