New to the site, please help, knock sensor problem!

[CMohan]

Hi everyone, I am new to the site and am very fortunate to have found such a great source of information. I have come across a problem and I am praying for some help.

 

Recently, I have had a problem with my 1996 Legacy 2.5. The check engine light came on. I had it scanned and it was telling me it was the knock sensor. As I had recently placed regular gas in my car rather than the recommended premium, I thought no problem, I'll just put in some octane booster/fuel inj. cleaner and I should be all set. This was no good.

 

I then used some top-engine cleaner to try and fix the problem, also to no avail. I then use some MMO, drove about a 100 miles and changed my oil...the light stayed on. I also, since this happened, changed out the spark plugs as well as the fuel filter and nothing is helping.

 

Today, I went to a salvage yard and found a knock sensor from a 95 legacy which was in relatively good condition. I took out the old, tried to replace it and ran into a few problems, mainly, he screw which holds the sensor will not tighten completely...it just keeps spinning around....also I noticed some sort of spring like contraption on the tread to the screw....I tightened it the best I could but needless to say, the stupid check engine light is still on. I'm gonna go to home depot and get a new screw to see if this will help. In the meantime, I have disonnected the knock sensor to see if my car's performance would improve, and no luck.

 

Since the light has been on my car has been sluggish on acceleration, often times hesitating a great deal...it's driving me crazy. Any advice on this matter would be greatly appreciated. I don't know if the timing is off, but I replaced the timing belt a year ago with the timing adjusted correctly, so I hope this is not the problem. Please help...Thanks.

[northguy]

Did you reset the computer? Instructions for this can be found on Legacy777's website. Go to the member's section, find his name, click on it and go to his website. You'll find a goldmine of info on late model Subarus. Good luck.

[CMohan]

Thank you for the reply. I went to the website, but unfortunately, the reset procedures are for 90-94 legacy's. Mines a 1996 so I need a scan tool...Does anyone know if disconnecting the battery will work? If it does, do I need to keep it disconnected for a long time? Any help will be much appreciated.

[SuBrat84]

That "Spring thingy" that came out on your screw was the inner thread of what ever you were trying to screw into.. you stripped it.. probably need a tap .. unless it's something you use a machine screw for.. then u just need a bigger machine screw..

 

As far as the hesitation goes.. have you tried replacing your spark plug wires? My #3 wire was bad and it was causing me a ton of hesitation and CEL was on. New wires helped a lot. Good luck..

[CMohan]

Luckily, I think I can just get another machine screw and work it in like that. I haven't replaced the spark plug wires, which is something I plan to do in the very near future. Hopefully that will solve all the problems.

 

One more question, does anyone know if the CEL should stay on if the knock sensor has been disconnected? And will disconnecting the battery work? Thanks for everyone's help, it is much appreciated.

 

 

That "Spring thingy" that came out on your screw was the inner thread of what ever you were trying to screw into.. you stripped it.. probably need a tap .. unless it's something you use a machine screw for.. then u just need a bigger machine screw..

 

As far as the hesitation goes.. have you tried replacing your spark plug wires? My #3 wire was bad and it was causing me a ton of hesitation and CEL was on. New wires helped a lot. Good luck..

[brus brother]

And will disconnecting the battery work?

 

Can't hurt, except for your clock and radio presets. Disconnect the negative terminal and wait about 20 minutes. Also, not sure how this might affect your alarm settings but batteries get changed so this shouldn't be the end of the world... that's next week. G'luck.

[CMohan]

Thanks for everyone's help....I love this site

And will disconnecting the battery work?

 

Can't hurt, except for your clock and radio presets. Disconnect the negative terminal and wait about 20 minutes. Also, not sure how this might affect your alarm settings but batteries get changed so this shouldn't be the end of the world... that's next week. G'luck.

[wcn00]

Thanks for everyone's help....I love this site

 

The "springy" thing that came out with the knock sensor retainer was probably a little device that you can use to "replace" the threads when you strip them. The last guy to touch it probably did the stripping.

 

Have you replaced your plugs? It's a bad job and must be done from the underside, but made a big difference for me.

wcn

[outback_97]

http://www.geocities.com/hobiegary/hesitation.htm

 

Anyone else here see this site before?

 

I was reminded of it in reference to the knock sensor... the page was last updated in '02 and I have no idea if this guy is making these anymore. Any possibility that this would help?

 

Steve

[magnoman]

Hi, I have a 98 outback that recently started to hesitate and surge on accel and will just

start pinging up hills on the highway. I have changed , wires, fuel filter, ing coil, spark plugs, used cylinder cleaner, injector cleaner. checked PCV & EGR valve and all Vac lines!

Could this be the knock sensor and where would that be?

 

 

 

 

Hi everyone, I am new to the site and am very fortunate to have found such a great source of information. I have come across a problem and I am praying for some help.

 

Recently, I have had a problem with my 1996 Legacy 2.5. The check engine light came on. I had it scanned and it was telling me it was the knock sensor. As I had recently placed regular gas in my car rather than the recommended premium, I thought no problem, I'll just put in some octane booster/fuel inj. cleaner and I should be all set. This was no good.

 

I then used some top-engine cleaner to try and fix the problem, also to no avail. I then use some MMO, drove about a 100 miles and changed my oil...the light stayed on. I also, since this happened, changed out the spark plugs as well as the fuel filter and nothing is helping.

 

Today, I went to a salvage yard and found a knock sensor from a 95 legacy which was in relatively good condition. I took out the old, tried to replace it and ran into a few problems, mainly, he screw which holds the sensor will not tighten completely...it just keeps spinning around....also I noticed some sort of spring like contraption on the tread to the screw....I tightened it the best I could but needless to say, the stupid check engine light is still on. I'm gonna go to home depot and get a new screw to see if this will help. In the meantime, I have disonnected the knock sensor to see if my car's performance would improve, and no luck.

 

Since the light has been on my car has been sluggish on acceleration, often times hesitating a great deal...it's driving me crazy. Any advice on this matter would be greatly appreciated. I don't know if the timing is off, but I replaced the timing belt a year ago with the timing adjusted correctly, so I hope this is not the problem. Please help...Thanks.

[hklaine]

Knock Sensor Location

 

[Gnuman]

Hi, I have a 98 outback that recently started to hesitate and surge on accel and will just

start pinging up hills on the highway. I have changed , wires, fuel filter, ing coil, spark plugs, used cylinder cleaner, injector cleaner. checked PCV & EGR valve and all Vac lines!

Could this be the knock sensor and where would that be?

under and behind the intake manifold, just to the right (if looking from the front of the car) of the Throttle Body. It is a black doughnut looking thing with a bolt in the middle of it. Look for cracks in the casing, and scan for codes relating to it (you will need a scan tool to do this, but should probably get one anyway if you are going to do much work on your Subie anyway)