Subaru Impreza 2009 turns over but doesn't start

Maintenance/Repairs
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1

My wife’s 2009 Subaru Impreza had been flawless for the last 40,000 miles - now it is difficult to start when the temperature drops and just lately, the engine will turn over but will not start at all.

Ou local garage replaced the original battery a year ago, and that seems to have been when the trouble started - it has since been replaced twice, each time seemed to be a temporary fix. The last fix lasted only a couple days.

It has been gone over with a fine toothed comb by two trusted local mechanics, and since the plugs, cables and coils were replaced it is worse than ever. It had to be towed the last time, and lasted two days before it had to be towed towed again - this time to a garage specializing in Subarus after the 1st mechanic gave up. It turned over easily but would only start with a higher voltage jump start or freshly topped off battery. They checked all the sensors and everything else they could think of and swapped out battery and coils. It seemed only to start with higher voltage. They could not make it start reliably, gave up and told us to take it to a Subaru dealership.

We took it to a Subaru dealership where they had it for two weeks. It started fine for them every time, and they could not replicate the problem, even when they ran the battery down.

We got it back 4 days ago and it started and ran fine until today. The temperature dropped to near zero last night, and again, this morning the engine turned over rapdly, with no sign of ignition, at all.

It has been a great car and totally reliable for 40,000 miles, but we are about to give up on it.

2

Does this mean the battery cables were replaced?

The only thing that I can think of is that the battery posts may be corroded, but I think you said that the battery was new and it did the same.
Then I would wonder if the alternator is over charging and frying the new batteries.

Yosemite

3

Cranks ok but only pops and runs if the battery voltage is on the high side? I think you may have a grounding problem somewhere. The engine, engine head, and battery negative all have to be soundly connected to the chassis. This occurs at various places around the engine compartment. Especially check the ground connection b/t the cylinder head and the chassis, as if that was missing it could cause the fuel injectors to fail intermittently. The engine must be connected pretty solid to the battery negative somehow already b/c otherwise it wouldn’t crank.

4

It could be the crankshaft sensor. Try replacing it.