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Knock sensor 101 and replacement


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  • 1 month later...
That doesn't have a knock censor. Unless you meant Legacy??

 

Then what is this $80 part that come up when i search for a 1990 Subaru Loyale Knock Sensor? part #KS89

My CEL comes and off at what seems to be random times, my mechanice said it maybe my knock sensor.. I need to get my washington state emissions test,however, from what i understand it will be an automatic fail if the CEL is on.. (this is my first test in the state of Washington, NY does a safety check)

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Then what is this $80 part that come up when i search for a 1990 Subaru Loyale Knock Sensor? part #KS89

My CEL comes and off at what seems to be random times, my mechanice said it maybe my knock sensor.. I need to get my washington state emissions test,however, from what i understand it will be an automatic fail if the CEL is on.. (this is my first test in the state of Washington, NY does a safety check)

 

1990 Turbos only.

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A 1990 model is OBD1, you can hook the test connectors under the dash together and it will flash the codes that are set. I think there are specific instructions in the USRM, or you can probably find them by searching.

 

?? Not on a loyale. It isn't OBD anything. It's like the rest of the SPFI cars, the RED LED on the computer itself flashes the codes.

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I fixed my CEL with electrical tape, although I suppose that wouldn't work in a state that wants it to be off... You could rig it up to turn on when the engine is off, then turn off when the engine runs... That's probably what I'd do...

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  • 5 months later...

(bump)

 

One more point to the statistics:

 

'99 OBW running a '95 EJ22 out of an Impreza with no codes related to the knock sensor, but running like crap. SERIOUSLY underpowered at low RPMS (bad enough you may consider turning off the A/C if you need to join the interstate). After 2500 RPM the car has somewhat decent acceleration.

 

The knock sensor looked fine but after removing it I found it had a crack on it's side (see picture). It may be a placebo effect, but it *looks* like I may have gained a few HP after replacing the knock sensor with a Beck Arnley unit

post-38670-136027657482_thumb.jpg

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also, I know from experience that if the knock sensor goes bad to where it doesn't read knock but carries the right resistance, that the computer will advance the timing, hunting for it's limit with fuel given and ping like hell. My 90 did that until I replaced it. I lost a few horse and gained some fuel mileage.

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  • 1 month later...

I was getting the infamous P0325 Knock Sensor code on my 95 2.2 (correction) Legacy Wagon with 199K miles on it. Thanks to FairTax's :banana:post, I decided to tackle this fix.

 

I removed the old sensor, cleaned up the surfaces, then re-installed. Got the code again immediately. (I had disconnected the battery for 10 minutes, in order to clear old codes.)

 

The old sensor had no cracks. I measured its resistance and got 550 ohms. Wiggling around the wire and connector, I found no loss of continuity. In my hands, it didn't seem to be a bad sensor. When installing it, I had even used a torque wrench to tighten it to the lower end of the torque range.

Still, I was getting the code.

 

So, I bought a new Knock Sensor online for $13, shipped. (A good price, by the way. NAPA wanted about $50, and Subaru wanted even more.) I measured the new sensor's resistance and got the same reading as the old sensor. I installed the new one, cleared the codes, then went for a long drive. No CEL!

 

The car still seems underpowered, though. On freeway on-ramps, it must be floored to get up to speed in time, and it's best to turn off the AC. I was hoping the new knock sensor would give some power back, but no luck.

 

This car is operating near sea-level -the car is so underpowered that it would be dangerous at higher elevations.

 

I should have mentioned this, too: It's an automatic. Also, we have to run the 10% alchohol blend fuel here, so there's less energy/gallon than real gasoline, but that's all we've had here for years. I run "regular" octane in the Subie.

Edited by 95LEGOBW
typo, incorrect engine - it's a stock 2.2
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The car still seems underpowered, though. On freeway on-ramps, it must be floored to get up to speed in time, and it's best to turn off the AC. I was hoping the new knock sensor would give some power back, but no luck.

I'm glad my write-up helped you find your way in the wild and wonderful world of auto repair!

 

I'd suggest starting a new thread describing your cars troubles in detail. We also need to positively identify the year, and the engine in the car, since the 2.5 wasn't even available until 96. At least not on the U.S. market.

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. . . . . We also need to positively identify the year, and the engine in the car, since the 2.5 wasn't even available until 96. At least not on the U.S. market.

 

My mistake, it was correct in the title, but not in the text. It's the stock, original 2.2. Must have had displacment envy and typed 2.5 by mistake.

Edited by 95LEGOBW
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. . . . The car still seems underpowered, though. On freeway on-ramps, it must be floored to get up to speed in time, and it's best to turn off the AC. I was hoping the new knock sensor would give some power back, but no luck. . . . .

 

Source of slowness found: The car had thick rubber OEM floormats. The driver's side mat had slid forward under the gas pedal, restricting the pedal's movement.

 

Fixed mat, and attached it to the seat posts to prevent further problems. Now, the gas pedal goes full travel, and the automatic transmission can be made to downshift when needed. Acceleration restored! It's still a slow car, but it's no longer unsafely slow.

 

Just wanted to close this loop. Thanks for all the help, folks.

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