Subaru legacy GX wagon, 1999 auto 2.5L non-turbo. Had the engine rebuilt a while back, then a few weeks later the thing won't start. Here are the symptoms, hopefully someone can advise me of what the likely problem is?

Engine starts fine when warm, no problems while driving etc but cold starts are a bitch. Now it won't start at all. It was a problem that developed over a few weeks, every now and then the engine would hesitate a bit at startup, until it just gave up altogether.

The fact it drives fine and starts fine when warm makes me think it's most likely a coolant temp sensor fault? I know there are a whole lot of things that can prevent a car starting but can anyone help out with suggestions of anything I can do/investigate to get closer to diagnosing the problem?

Thanks.

 

Either Crank sensor or Coolant temp sensor as you said. My temp sensor went and got progressively worse. replaced it, ecu reset and much better. Temp sensor is the cheapest one to buy first!

OR! could be a spark/coil pack!?

 

Can you decribe the symptoms of your temp sensor failure? Does it sound similar?

For a while, when cold, my engine would start but kind of sputter, and be a bit half-assed about it for a few seconds. Never any problems after driving for a while and warming up. Would a crank sensor or spark plug fault cause the same behaviour?

Cheers.

 

a spark or cracked coil pack could cause lazy start but would also mis-fire.

I always had some starting problems since owning the car. Starting from cold would always be first time no problem. If doing a short trip - say leaving the car for a few mins to settle when warm, it would struggle by just turning over and over. Eventually it would just burst into life. In the end - it just became sooo lazy from cold, coughing and spluttering. Thats when I changed the sensor. I did the crank sensor first - although it did make a slight difference, changing the temp sensor and re-setting the ecu finally sorted it out!

Hope this helps