Hey Scotty. Hope your christmas is going well. My 2009 subaru forester has 276k miles on it and it has developed some issues. It now idles very low to the point where it almost stalls. Something is whistling very loudly while accelerating.
low idle and whistling sounds like it could be a vacuum leak. Would also explain that Cat code.
It's possible your engine is wearing out. If it still has the original head gaskets they are likely to fail in the near future, if they have not started leaking already.
https://www.carcomplaints.com/Subaru/Forester/2009/
However I would expect other symptoms if there were a serious internal engine problem.
You can try cleaning your throttle body and MAF sensor using the appropriate cleaners. You also might want to perform a diagnostic scan for codes and live data to look for problems.
@chucktobias I already did a scan and it has a code for catalyst efficiency. Their is an oil leak but i dont know if its coming from head gasket or valve cover.
Does the engine have a turbo charger? I'm trying to figure out what the whistling sound might be while accelerating.
If you have access to a scan tool then look at the long and short term trim levels. Positive trim numbers means the oxygen sensor is detecting a lean air-fuel mixture (too much oxygen). Negative trim numbers indicate the oxygen sensor is detecting a rich air-fuel mixture (too much fuel).
You'll want to graph oxygen sensor 1 to make sure it's functioning correctly.
Also check the mass airflow sensor (MAF) reading. A rough rule of thumb is it should read close the liters if the engine. For example a 2.5L engine should read somewhere around 2.5 grams per second.
Some turbo engines have a manifold absolute pressure (MAP) sensor instead of a MAF sensor. Which reads the atmospheric pressure inside the intake manifold.
@oskool the long term and short term fuel trim is in the negatives
@bzboyd2 Negative trim values means the engine is running rich. What are the MAF, MAP, BARO, IAT, and ECT sensor readings?
@bzboyd2 How negative are the short and long term trim values?
@oskool short is around -5 to 0 long term goes to -2 to -.8
@bzboyd2 Those fuel trim numbers are pretty close to ideal. I don't see anything in the trim numbers pointing toward what's causing the rough idle unfortunately. I'd consider running a cylinder compression test next.
I already did a scan and it has a code for catalyst efficiency. Their is an oil leak but i dont know if its coming from head gasket or valve cover.
@bzboyd2 When you did the scan did you see anything out of sorts in live data?