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Guest Message by DevFuse

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1997 legacy bogging down and knock sensor going off

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7 replies to this topic

#1 katie1982



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Posted 25 September 2013 - 12:56 AM

Hey, just hoping to get a little insight on my new-to-me car. Knock sensor started going off a few tanks ago, so I have added fuel injector cleaner (one btl.) then I've been using octane boosters in succeeding tanks. Now it is bogging down on occasion when at lower speeds and lower rpm. 

I am thinking fuel injector problem, but also, there is loud whistling whine that is noticeable when I accelerate hard (as in passing another car) or accelerate uphill. Also, the knock sensor and the bogging only seem to happen after I have driven the car above 60 mph for a while (longer than 20 min).

I am not much of a mechanic, but my friend is. I'd like some thoughts on where to point him. As of this post, the only code is the knock sensor. 

#2 heartless


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Posted 25 September 2013 - 06:46 AM

if you have a code for the knock sensor - start by replacing the knock sensor. These are relatively cheap and easily replaced, and are a common "problem".

New knock sensor - make sure it is installed in the same position the old one is in, clear the code, and drive for a bit to see if the bogging goes away - betting it does.


also, knowing year, model & mileage of the car might be helpful in diagnosing other issues.

#3 idosubaru


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Posted 25 September 2013 - 07:00 AM

what heartless just said,. replace the knock sensor, very common wear item.  they're on ebay for like $10.



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Posted 25 September 2013 - 08:24 AM

pay close attention to the connector when ordering off ebay.  There are two different plugs I've seen used on 97's.  One of which will cost you around $12 shipped the other $9 shipped.  I've ordered both in the last two months.

#5 ivans imports

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Posted 25 September 2013 - 09:45 AM

front o2 senser not responding properly runing lean

#6 katie1982



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Posted 25 September 2013 - 09:26 PM

Thanks guys, glad to hear no one thinks its dying. It is a 97 legacy with about 222,219 miles, driven in AK. Clearly has been beaten up, but has a good heart. Thanks for the inputs!

#7 heartless


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Posted 25 September 2013 - 09:35 PM

no, your car isnt dying, :)


I have a 1990 with a little over 236, 000 and still going pretty strong. just had a deer try to take it out this evening :o  - it only managed to dent the front fender, and break the passenger side mirror off - otherwise she is fine.


get that knock sensor taken care of, and see how things go - if it still has issues after a week or two on the new knock sensor, report back and we will try to help you sort it out.

#8 Fairtax4me



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Posted 25 September 2013 - 10:22 PM

Not quite sure what you mean by "going off". Is the Check Engine Light on?

If its pinging that's a sure sign the knock sensor is NOT working, since the knock sensors job is to detect pinging so the ECU knows to dial back the ignition timing to prevent it. You may not always get a code for a bad knock sensor, but it can cause the car to ping and lose power if it goes bad.

Other things that will cause pinging are an excessively lean fuel mixture, (can be caused by a vacuum leak, dirty or bad MAF sensor, bad O2 sensor,etc) or the engine is overheating.

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