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Old 01-17-2011, 11:24 AM   #1 (permalink)
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Default 98 knock sensor issues

i have a 98 that has a knock sensor cel code and have changed it just recently. i was wondering if there was any way at all to check to make sure it isnt the actual sensor and is the wiring that is the flaw because like i said i just changed it cleared the computer and it still is coding. the thing is when i changed it i had accidently ripped off the male end of the harness connector right off the engine harness and hard wired it with no plug.....is there any way to just overirde the knock sensor im sure there isnt but it is just a question....
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Old 01-17-2011, 07:10 PM   #2 (permalink)
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First, do not override the knock sensor - you might regret it some day.

Second, the only thing ECU checks is the impedance (resistance) of the sensor, so if that checks out (with a simple multimeter; should be ~500-600KOm, iirc), then it's the wiring. Get a wiring diagram and start testing/fixing.

P.S. Lack of knock sensor code does not necessarily means that the sensor is working well, as per (2) above. Also, rather easy to crack the sensor if overtightened.

P.P.S. Many knock sensor issues (timing retardation, hesitation) are caused by bad engine bay and other sensors' grounding. This will not bring up the
"knock sensor fault" code though.
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Old 01-18-2011, 06:43 AM   #3 (permalink)
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thanks for the info....you answered my question 150% .....my next question seeing i got it answered for me was what was the impedance for the sensor? lol but you got that for me already. thanks, I'll have to check the impendance of the sensor. if it checks out is it possible there is a knock? which would totallypiss me off lol...especially after a timing belt, waterpump, brakes, and all the money i have into it already....

as for the p.p.s. i wanted to know if there was an aftermarkt grounding kit for these cars or should i just go through and clean up all the ring terminals and ground points on the frame and motor of the car? they all "seem" to look ok but i do know looks are always decieving...

Last edited by 98foresterct; 01-18-2011 at 06:50 AM. Reason: one more question
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Old 01-20-2011, 06:52 PM   #4 (permalink)
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1. I'll have to check the impendance of the sensor. if it checks out is it possible there is a knock?


2. i wanted to know if there was an aftermarkt grounding kit for these cars or should i just go through and clean up all the ring terminals and ground points on the frame and motor of the car?
1. Possibly (in either case of sensor being bad or the wiring - if ECU does not see the sensor, it cannot use it; I dunno whether it then goes into "safe mode" with retarded timing; it might not). But do not worry too much just yet - if the engine is otherwise good and clean, and the gas is good and clean (at least 87 octane preferable; while you're dealing with this issue, might as well use premium gas to be safe), then you should be ok. And bad knock (detonation; it does not sound like "knocking" until something is broken big time) can usually be heard (it is usually too late by then though).

2. Yes. Search/google it. Paranoid made it at some point, may be others, too. And yes, rebuilding grounding points is also an option, and it's a lot cheaper if you have few hours to spare (I am sure I posted detailed instructions a few times already).
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Old 01-25-2011, 03:28 PM   #5 (permalink)
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1. Possibly (in either case of sensor being bad or the wiring - if ECU does not see the sensor, it cannot use it; I dunno whether it then goes into "safe mode" with retarded timing; it might not). But do not worry too much just yet - if the engine is otherwise good and clean, and the gas is good and clean (at least 87 octane preferable; while you're dealing with this issue, might as well use premium gas to be safe), then you should be ok. And bad knock (detonation; it does not sound like "knocking" until something is broken big time) can usually be heard (it is usually too late by then though).

2. Yes. Search/google it. Paranoid made it at some point, may be others, too. And yes, rebuilding grounding points is also an option, and it's a lot cheaper if you have few hours to spare (I am sure I posted detailed instructions a few times already).
awesome!!! thanks so much for your help.. i am not currently driving it as of right now so i will have to run the gas out of it and try some high octane and see what happens then i will go through and re wire if needed. but thanks again for the help you have helped me the most on here so far and i am really thankful for it.
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Old 02-08-2011, 11:56 AM   #6 (permalink)
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ok.....so I have been pretty lazy lately ....lol.... i have not tried anything on it yet but i did do some more research. Which brings me to the question what if the connections are all good and everything is perfect, but the degree of the actual sensor wire is wrong? will that cause it to code? i saw on scoobymods.com... the actual instructions for installation on the sensor and it says either 45 degrees or 60 degrees from the back of the motor is the angle it should be. Is it possible its throwing the wrong resistance because of bad location? im not sure if you are a member there as i am not so i cannot reply to it, but which angle should i be using? or does it truly matter?
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Old 02-08-2011, 12:21 PM   #7 (permalink)
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45 degrees or 60 degrees from the back of the motor is the angle it should be. Is it possible its throwing the wrong resistance because of bad location?
Repositioning the sensor to the above angles shouldn't be much of a hassle. Give it a try and see if that answers your question. What really matters is the amount of torque applied to the sensor bolt upon installation. I believe the range is 16 to 18 ft-lbs. What torque setting did you use? Also, It's not a bad idea to make sure the surface area beneath the sensor is free of debris and grime.
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Old 02-08-2011, 01:15 PM   #8 (permalink)
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Repositioning the sensor to the above angles shouldn't be much of a hassle. Give it a try and see if that answers your question. What really matters is the amount of torque applied to the sensor bolt upon installation. I believe the range is 16 to 18 ft-lbs. What torque setting did you use? Also, It's not a bad idea to make sure the surface area beneath the sensor is free of debris and grime.
hahaha yeah i thought about the over tightening thing but im pretty sure I torqued it to spec....its just been wayyy to cold for me to crawl around in the snow bank its in and mess with it. lol im going to try the new gas, (10 gals of 93) that engine restore stuff in a can (4cyl formula) (used it on my honda and it stopped it from smoking as they ALL do lol), injector cleaner from lucas, and try to clean ground points and re-do the wiring and set it to the angles above after i do a visual inspection on the sensor itself to see for cracks this weekend when i have the time to shovel it out of the snow bank its in. thats where i am going to start and see where i get with it as it is supposed to be really cold this weekend. if i dont figure it out this weekend ill make sure to post and let you guys know where i am at and if it is still coding. but thanks for the help I hope i figure this out soon i want to drive it in the snow :)
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