[mhackney]

Ok, well, I am having trouble finding the knock sensor. Spent an hour searching here, YouTube and even with the factory manual (the line drawings are horrible) I can't be 100% certain I've located it. Here are photos of where I think it and the connector is. Does this look correct?

2010 Forester
Top photo is looking over driver side fender. The blue circle is what I think is the knock sensor connector, the red rectangle is just to provide a frame of reference. My hand is over the EGR valve that I replaced last week.

Is that the connector?

 

[mhackney]

While I was in there looking for the connector I scrutinized all the vacuum hoses and did a brake cleaner leak test (including around the brake booster). Nothing out of the ordinary was found.

 

[bman400]

Unless they moved it in your 2010, it's located on the block on the drivers side of the throttle body and it looks something like this:

 

[mhackney]

Here is what the official Subaru service manual shows. I'll go out with a mirror and see if I can find it for sure.

 

[mhackney]

Ok, I verified that the photo I posted above is the connector. I can trace the wire down to the sensor that looks like your photo. But try as I might I can't get the connector separated even with a small screw driver inserted. There just is no room to get enough fingers in. I will need to do some disassembly and better lighting later to give it another try.

 

[bman400]

You'll probably need a pick instead of a screw driver for that connector.

 

[mhackney]

I have a pick (I was using a tiny flat blade driver, maybe 2mm across). It isn't clear where the latch is since I can't really move it around enough to see. I'll keep looking.

 

[mhackney]

Ok, wow, I finally got it disconnected. I found a similar connector to practice on. The main issue is that there is no room down in there to get a grip on both ends. I finally grabbed the socket end with a big pair of pliers with a little pad I super glued to a jaw to depress the connector lever. That worked but I still got pretty scraped up!

But, taking it for a drive, the stall still occurred. I noticed the cruise light on the dashboard was also on with the CEL.

Anyway, that test is complete. Hopefully the others will go more easily! What's next?!

 

[bman400]

Well that eliminates the knock sensor. Temperature sensor of some sort would be my next guess. Not sure as it's weird why it works fine when cold but once it warms up it goes south.

 

[mhackney]

Is it possible that this is being caused by the transmission in some way? The fact that neutral and park also idle correctly but drive and reverse do not is perplexing to me. Is it possible to increase the idle speed a bit? I bet even 50 RPM increase would solve this.

 

[mhackney]

I have checked the transmission fluid and is both filled and in good shape (it was changed not too long ago when the head gasket and timing belt were done).

 

[bman400]

IDLE speed is not changeable, there is no "idle screw" on these vehicles.

 

[mhackney]

But, even with the transmission in drive, after the RPMs drop, if the engine doesn't stall, it immediately comes back up to normal. Just really odd behavior.

I’ve also googled this symptom without specifying a make/model and nothing came up.

 

[bman400]

I believe your vehicle has the external AT fluid filter, is it still the factory filter? If it has been changed, was it changed with the Subaru OEM filter and not some after market filter? Non-Subaru OEM Filter are known to cause hydraulic pressure strangeness inside the transmission.

 

[mhackney]

I don't know the answers to any of those questions but I will track it down and find out! thanks!

 

[bman400]

If you're standing there on the driver's side. And looking down into the engine bay towards the transmission/transmission pan, you may see the external ATF filter, it's a can pointing sideways. If you don't have the can, then you don't have the external filter. Take a picture.

 

[bman400]

Post # 17: ('09-'13) - 2009 - Automatic fluid change?

 

[mhackney]

It doesn’t look like it has it. Impossible to get a good photo with all the hoses!

 

[bman400]

Different angle, from under the driver's side door would give a better view.

 

[mhackney]

I didn't see your second post with the link to the thread and photo. It is too dark now but I'll double check in the morning. However, the service manual does not list or show a filter in its service schedule.