Car will start when it is warm, but refuses to crank when cold

Identical cold start issue on my Astra IE 1996 F series after the engine got rebored - after months the new oil pump was found to be faulty & clogged-up & replaced by the spares supplier - the car then ran perfectly after this. I was told the blockage created a backpressure & the computer was stopped it starting.

16 years later - 10 yrs after the last service covering just 8600km (last 2 yrs car hardly started) has identical cold issues again. It can be driven around & wont take long cold start in our warm coastal winters. The good mechanic seems to be giving up trying to fix my old car but refuses to believe its a low oil pressure issue saying that just makes the oil warning symbol light up & doesn't affect a car starting. I want to check if the engine warning light works on starting showing the low oil pressure sensor is working. But his now busy searching for a Astra specific temperature sensor.

Before you start it cold, prime the fuel pump twice or three times. Lets make sure you have adequate pressure.

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check the cold start sensor and injector wires .take off and clean them.

There are several things that few people know about starting cars in cold weather. 1. Check your battery to make sure it is not rusted, leaking, and has a charge 2. Jump start your battery with another car, even if you believe the battery is good, this often times will still start your car. 3. If your engine is cold, and you have an older car, ensure to get your fuel lines to the engine flushed or have fuel injection service performed 4. The engine tends to warp the same way wood does during the extreme cold, do not be afraid to continue trying to warm up the engine by constant cranks with it is cold out. Your not going to hurt the car, the worse that could happen is too much fuel will enter the carborator and cause flooding in the system to occur. Wait 20 minutes if this happens and start to crank again 5. Bad spark plugs are a major reason why many cars take a very long time to start 6. Please have your spark plugs removed and exchanged for new ones. Over time, spark plugs become fowled and prevent the car from starting even thou you hear cranking!!!

I have a '97 Saturn SL and had the same problem. If the car was cold when I started it, it started up no problem. If I had just come back from driving it and turned the car off, let it sit for about 5 min, and tried to start it again, the starter would turn but the motor refused to turn over. I ended up replacing the O2 sensor and the engine temperature sensor. I haven't had a problem since then. O2 sensor can be kinda pricey though. Good luck!

dos your car crank, if it does check fuel pressure
if does have fuel pressure check spark most likely your coil or ignition module but if doesnt crank check to see if you get signal to your remote starter with a test light

Check cam/crank position sensors

change the crank censer.

Sounds like the EGR valve is bad.