1998 Forester Knock Sensor - CAN'T LOCATE! HALP!

Redline

Redline

Member
Okay, so the OBDII scanner at Advance says my new-to-me Forester has a bad knock sensor. Advance has them in stock for $75. How much of a job are we talking about here? I'm pretty capable, but I'd prefer to plan accordingly if I'm going to rip into an engine block.

Any help is appreciated. I heard something about getting the degree rotation exactly correct on the sensor, or it wouldn't work... true?

 
it takes about 5 min and a (i believe) 24mm on an extension. it does have to be tightened just the right amount, so you'll need to find the spec on that.

 
To the left of the throttle body. Its a plug connected to what looks like a large washer. It took me 5 mins, mostly because it was a hard to reach spot and I have big hands.

 
Cool deal - will fix this afternoon.

Torque spec? Gud-n-tyte?

<doesn't own a torque wrench>
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one thing with a knock sensor install is that the sensor has to be aligned a certain way to work properly. Look carefully at the old one before you take it out so you get new one in same position.

 
That's what I was asking above, about the degree of rotation...

Assuming the old one WAS working at some point, your direction works. If the current one was just installed improperly, then I'll never get it right. Is there a scientific way to determine exactly how it's supposed to be aligned? Is it exact, or does it have a margin for slight error?

 
Is there a scientific way to determine exactly how it's supposed to be aligned?
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yes...a mysterious book called a "Service Manual" :angel12:

not just the expensive factory-manual set, it's in the Haynes n Chilton ones, too.

why are you still wrenching on your cars without one???!!!! :nono: :happy3:

 
Advance Auto lacks said manual, Mr. Nigel.

Okay, so I found a pictoral definition of the knock sensor location - and my sensor isn't there! I can't even find a pigtail connector! I see the threaded hole it's supposed to screw into, but no sensor.

Obvious: It's possible the sensor was removed at some point because of an engine swap??? But to not find a connector is just not right.

Not-so-obvious: Maybe I'm looking in the wrong location? Can anyone with a 1998 (DOHC) Forester point me in the right location? The scoobymods pic shows straight underneath the intake, below the throttle wires.

 
i'm pretty sur when your standing in front of the car if you look down below the rightside of the throttlebody it should be there a plastic ring with a bolt through the center

 
Okay - took another looks this morning. Found it. Not where it's supposed to be?? Very wierd. It seems like it was relocated. Also confirmed the wire is long enough to put back to original (read: correct) location. Unless it was moved for a purpose?

 
that's odd. my stepmom has a 99 forester and its on teh right side as shown above. is your 98 dohc? maybe they were on the other side.....

 
Yes, DOHC. I'll try using the existing location, but will change back if the CEL persists. I don't want to go relocating crap unless it's called for.

I thought your mom had a 2001?

 
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