Knock Sensor Vote

Collection of technical archives from the BC-BF LegacyWorks Yahoo! group.

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FormView

Knock Sensor Vote

Post by FormView »

Hi. I have a 1990 Legacy LS, non-turbo, automatic, and about 150K
miles. The computer recently said my knock sensor was bad (I looked
at it and it was cracked), so I purchased a new one.

When I replace it should I put a rubber washer on the bottom, on the
top, both places, or just install it with no rubber washer? I really
haven't noticed a problem before it cracked, but I just wanted to get
some opinions.

Thanks,
Joe
Josh Colombo

Knock Sensor Vote

Post by Josh Colombo »

If you want to add the rubber thing.....I'd probably only put it between the sensor and engine block
FormView

Knock Sensor Vote

Post by FormView »

Have you put a rubber washer on yours?
Douglas Hancock

Knock Sensor Vote

Post by Douglas Hancock »

thats were mine is. I only done it knowing that I had lost power though.
Douglas Hancock

Knock Sensor Vote

Post by Douglas Hancock »

yep. between engine and sensor. I have a turbo though. Have a noisy lifter. sensor was picking it up and putting it in saftey mode.
Josh Colombo

Knock Sensor Vote

Post by Josh Colombo »

I have a fiber drain plug washer on mine. The rubber will prob help muffle more noise, however not sure of the longevity, compared to the fiber one.

Josh
FormView

Knock Sensor Vote

Post by FormView »

My valves aren't too noisy - most of the time. I don't know how to
tell if the sensor hears the valves tapping ot the engine knocking.
FormView

Knock Sensor Vote

Post by FormView »

I'm sure I could pick up someting at the local parts place. I don't
think I would want to muffle it too much.
ciper_

Knock Sensor Vote

Post by ciper_ »

Although I agree with this modification I dont see any of you mentioning that you have replaced the knock sensor. The knock sensor design has been updated and this new design is noted by a different color plug. There is a TSB specificially about this. That bulletin explains how a wire with intermittant contact inside will cause the engine to go into full retardation.

Before trying to add a washer I suggest you make sure you have the latest version of the sensor. Both of my legacy had the older design. I ordered two sensors through subaru parts and all of my issues were solved (premium gas helped as well).
Josh Colombo

Knock Sensor Vote

Post by Josh Colombo »

I've got the updated knock sensor. I still had issues here and there. It would be horrible right after an oil change. I don't know......it still seems have issues even after the fiber washer. Could be too that my tranny is just an unbelievable piece of shit. Oh well.

Josh
Douglas Hancock

Knock Sensor Vote

Post by Douglas Hancock »

No problems at all. Found the peice of rubber in the shed, so it cost nothing. Use a bit of old radiator hose if you have one. My biggest noise from the engine was the tappets an it solved that. That would be the loudest engine noise you would get unless there was something totally wrong with your engine.

Regards Doug
Newcastle (Australia)
FormView

Knock Sensor Vote

Post by FormView »

What color is the new plug?
Josh Colombo

Knock Sensor Vote

Post by Josh Colombo »

I believe the new color is gray. The old color I think is white. Just look at the two connectors. If they are not the same color then you prob have the new one.
Z1Auto@aol.com

Knock Sensor Vote

Post by Z1Auto@aol.com »

Well, after getting an intermittent CE light (never stays on, only comes on when car is cold), I got the following today:

ECM (engine control module)
Knock sensor

Car runs fine, good gas mileage...from time to time, dependin where I get gas it seems, it is a bit sluggish in the revs under boost...other times, its fine.

Any pointers?

Adam
ciper_

Knock Sensor Vote

Post by ciper_ »

Thats what I have thought too.

Whenever the ECU detects an open or shorted curcuit on the knock sensor it will fully retard the engine. If you knock sensor has intermittant contact (part of what the revisions fixed) you will get temporary retardation (hesitation) and sometimes but no always a CE light.

Id say most random CE light flashes are problably caused by this. In shopping for a legacy the past few months I saw a couple that would flash the CE light breifly every once in a while.
Josh Colombo

Knock Sensor Vote

Post by Josh Colombo »

I would clear the codes, try the active diagnostic thing by connecting both connectors. See if anything pops up. If not. Drive the car....see what pops up later. (that info is on my site)

On a side note....knock sensor is like 30 bucks.....it's cheap. If you get both the codes again.....just replace the knock sensor. The car is complete and utter dog when the sensor is not reporting correct signal to ECU. Mine was freakin out when I was testing the electrical fix to dampin the sensor.

Josh

PS: Adam, any word on the sti top mounts, whether they're still back ordered or not? Thanks man.
Z1Auto@aol.com

Knock Sensor Vote

Post by Z1Auto@aol.com »

Josh - thanks for the heads up.

i am the car now doing the ew turbo and IC...hopefully it goes in tonight, but certainly by tomorrow night..man there is a lot of gump after 167k!! All cleans up nicely thogh. We'll redo all the vacuum lines too while we are in there.

Question - I can get the knock sensor from our parts distributor tomorrow night.....is it hard to change once everything (exhaust, etc) is back in the car?

Adam
Rod_

Knock Sensor Vote

Post by Rod_ »

I was getting the knock sensor code intermittently also. Changed the sensor for a new one..... all fixed now. Also getting better economy. The new sensors are also less sensitive than the old ones.
cheers, rod.. in oz.
Josh Colombo

Knock Sensor Vote

Post by Josh Colombo »

The sensor if it is on the same side as the EJ22 n/a engine, it is on the driver's side, so exhaust should not be an issue. However the intercooler may restrict access to it. The connector that goes down to the sensor is right below the throttle body. There is a metal piece that has two plastic connectors held in it. I think one is for the crank sensor or cam sensor....the other is for the knock sensor.

Take a look where the sensor is, and where the intercooler is goin to be....see if it is in the way or not.

Josh
FormView

Knock Sensor Vote

Post by FormView »

The new one I just installed has a white connector, and the connector
on the car is gray, so I guess I have a new one (since the colors are
different). Unfortunately, I threw away the one I removed from the
car - it had a big crack in it and gave me intermittent errors.

I'll have to see if I get better mileage...
Douglas Hancock

Knock Sensor Vote

Post by Douglas Hancock »

You can get it out without removing the IC. You can grab it with one of those claw type things that get things in tight places were you drop stuff.
ciper_

Knock Sensor Vote

Post by ciper_ »

Hey guys, finally found that a copy of the TSB online

Check it out
http://members.tripod.com/quick_svx/TSB ... 48280.html
FormView

Knock Sensor Vote

Post by FormView »

Thanks for the link. It verifies the new knock sensor.

BTW - Is there a general link that has all of the TSB's? I have a
link that has TSB titles, but not the actual contents.

Thanks.
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