[dham94]

Hi guys,

I am new here and somewhat new to working on Subarus.

I have a 2004 Subaru Forester XT MT with 94k miles on it.

I was driving home from work one day and the car began to lurch and stall really bad. Eventually the CEL came on and blinking Cruise Control light. I limped it home and began to diagnose the problem.

I pulled the codes and found P0301 (miss fire in cylinder 1) and P0340 (Camshaft Position Sensor).

I just had the spark plugs replaced by the dealer in the last year or so, so I have kind of ruled that out as the cause of the issue and codes.

I swapped the ignition coils on cylinder 1 and 3 and the issues and CEL came back on. So I can assume the coil packs are good.

I pulled the spark plug to see if there were any carbon deposits or arcing happening. There was nothing.

I replaced the fuel filter and air filter because that needed to be done anyways. The issues and CEL still remain!!

I am kind of lost in what to do next. I obviously do not want to just keep replacing parts. Do you think the bad cam sensor is causing the misfire code in cylinder 1? Or is it the other way around? Does anyone have any experience with this issue? Also; Where is the cam sensor on the passenger side of the engine block?

Thanks for all of the help!

 

[kharmicresonance]

Your camshaft position sensors are on the back of the head just behind the fuel injector. Not easy to get at. So, looking at the engine, while standing in front of the car, cyl1 is closest to your left hand and cyl3 is right behind that. If you then move to that side of the car and really twist yourself around you might be able to see where the fuel injectors are - because they are hidden under the coolant reservoir and steel bracket/guard.

However, if a camshaft sensor goes out, you will usually get misfire codes for both cylinders in that bank.

also, if the engine suddenly started lurching while you were driving, it is more likely something besides a simple misfire, those are typically barely noticible. I have even seen an ej25 with two cylinders not running at all and the owner was saying it was "fine" and made "great power". It is more likiley that you have a mechanical issue, whether that is just timing belt slipped or something worse.

At 94k you are almost due for timing components to be replaced, valves to be adjusted, and compression and leak down tests anyway.

It is actually pretty easy to do the tests. They will tell if you have damaged valves. Then you can make a decision on whether to invest in the rest of the maintenance, or have to rebuild.