Astra does not start in the morning

My Astra 1.8 double overhead cam engine has trouble starting in the mornings and after it starts it lacks power. The crankshaft position sensor (CKP) and crankshaft
position sensor (CMP) were tested and are fine. The compression is 55 psi, there is spark, and compression is 120 psi in all four cylinders. The temperature sensor is also fine, but the oxygen sensor's resistance isn't heating up.

Good evening. I have a question about the Astra you're having problems with. Is it an ECOTEC engine with a VVT system? Also, what's the mileage on your vehicle? What type of oil are you using? What's the spark plug code? If you could provide the VIN (Vehicle Identification Number) of the vehicle, I'd appreciate it if you could check what options are available for that particular unit and perhaps I can help you with this.

That's right, friend, it's an ECOTEC engine with 145,000 km. It uses multigrade oil. The VIN is WOCTG223XY5294581. I don't have the spark plug number on hand, but the issue is that when it's cold, the pulse is low, and adding starting fluid to the throttle body makes it start roughly, but it runs fine once it warms up. My question is, could the oxygen sensor be related to this problem, since the heater core isn't working? The sensor is titanium. Thanks...

While I'm not a specialist in the make and model, based on the symptoms and what you've described, I suggest you perform a complete compression test (dry, wet, and air compression) to determine if there's a mechanical problem with the engine. Also, check the fuel atomization.
Remember that the lambda sensor affects the quality of the combustion mixture, but during the operating temperature phase, the sensor signal isn't crucial for calculating the amount of fuel. Check the temperature signal reaching the ECM.
I hope this helps.

Good evening. Regarding your question, I recommend performing component testing (rings and valves). I should mention that a compression tester isn't 100% reliable. I would recommend using a cylinder leak-down detector, as it's much more reliable than a compression tester. Also, in my opinion, it's an engine valve problem, either because they're carbonized, which is a common issue. Furthermore, if it's a VVT system and the engine valves are fine, I recommend checking the condition of the VVT ​​unit, as it's responsible for valve overlap and it could be damaged by using an unsuitable oil. Generally, semi-synthetic oil is recommended because it has actuators on the camshafts.
The ECM ignores the oxygen sensor signal during cold engine operation because it's not critical if the sensor is faulty. Additionally, if the glow plug is bad, the ECM could enter protection mode if it detects a fault.
I recommend using a Tech 2 to perform VVT component testing and cylinder leak testing. Also, if you have a very thick oil (20w 50), I would recommend changing it since it is not the right one for that unit and could affect cold starts.