HELP - Knock Sensor Location / Replacement

[deadlydave]

I took my 95 legacy 2.2 to advance autoparts yesterday to get the 'check engine light' diagnosed. It said I have a malfunctioning knock sensor. The part costs about 50 bucks, no problem. Whereabouts in/on the engine is this sensor, and how difficult is it to replace?

[Huffer]

Should be on the leftside (passenger side) toward the back of the block.

[AussieDan]

I'll give you a hand with it, it's on the top of the block just under and to the driver's side of the throttle body.

[Plays_with_Toys]

hayne's manual says that it is located under the intake manifold on the left rear of the engine. It says to take the intake manifold off and remove the sensor. When the sensor is removed, coolant will flow out, so you have to drain the coolant as well, and place a catch under the sensor for anything else that flows out. New sensor will have sealant on it, thread into the block to roughly 14ft lbs.

[2.5GT]

stupid question, but what exactly does a knock sensor do?

[legacy92ej22t]

hayne's manual says that it is located under the intake manifold on the left rear of the engine. It says to take the intake manifold off and remove the sensor. When the sensor is removed, coolant will flow out, so you have to drain the coolant as well, and place a catch under the sensor for anything else that flows out. New sensor will have sealant on it, thread into the block to roughly 14ft lbs.

Sorry but that is sooo wrong. There isn't any coolant involved with the knock sensor at all. It's more like a magnet that is screwed onto the block to detect...well, knock. Hehehe. I know you were just quoting a manual but if that's what it says then it's severly inaccurate.

I call the area that the KS is in "the pit of dispair" but on an EJ22E it's probably not half as bad as on an EJ22T. It's under the intake manifold and kinda the throttle linkage, on the driverside, towards the back half of the block. It's over #4. You don't need to take the intake manifold off but you'll need a good socket extension to get to it. It can be a bitch. Make sure you clean the area where the sensor screws to the block before putting the new sensor in too. You want a good connection.

[legacy92ej22t]

stupid question, but what exactly does a knock sensor do?

Think of it like engine sonar. It detects engine knock and sends a signal to the ECU which then usually retards your timing (not good for performance) to compensate. Knock is bad.

[legacy92ej22t]

OK, here's a pic that may or may not be of any help. I got tired of looking through all my pics and settled on this one.....for now at least.

Anyways. Do you see the ruuber line that comes up on the right side by the bell housing at the back? Well about half way on that line, down below it, you can see a silver circle with a hole in it in the block. That's where the KS goes. You can also follow the line in the casting that comes down off the starter/bellhousing bolt hole and it ends right at the KS location.

It's a hard pic to referrence because of all the missing parts but it will at least give you an idea I guess.

http://thawa.net/gallery2/d/875-1/PICT0839.JPG

[Huffer]

Weird. On my NZ car, the knock sensor was driverside (RHD), so I figured it would still be on the same side here. Guess they switched it.

[deadlydave]

thanks a lot guys. I noticed little if any difference in egnine operation...but i can watch my fuel needle move on short trips. :-( I'll post again in a week or two when I attempt the fix.

[BAC5.2]

The easiest way to replace the sensor? Unbolt the throttle body.

Really simple, 4 bolts and just pull it back. It'd be good to replace the gasket, but not required.

I remember when I installed my WRX intercooler, we had the throttle body off, and it was so easy to reach!

[legacy92ej22t]

The pit of dispair will make you pay if you take the easy way out! BEWARE, OF THE PIT OF DISPAIR!

Phil's always trying to do things the easy way. :roll:

:P

[deadlydave]

Hey everyone thanks for your help.

After dishing out the $63 for the sensor, and almost breaking my right hand and searing off my finger tips....It is installed. I decided to take the easy way out that aussiedan described to me. I didn't remove the throttlebody, since i had an extra long socket extender--I just took the bolt out. I disconnected the battery for a couple minutes, then restarted the car. The check engine light was still on--but after a while of driving...about a hundred miles of my trip to Philadelphia...it turned off. Car runs great.

And aussiedan's legacy sounds incredible.