Knock sensor replacement
#3
Access the KS from the driver’s side of the intake.
Use however many, appropriately sized, socket extensions that you find necessary, in combo with the appropriately sized socket swivel, to get your socket onto the KS bolt.
Patience and persistence are a virtue but it truly works … I’ve done it a number of times over the 25 years I’ve owned, driven, serviced and repaired my 4th Gen.
Use however many, appropriately sized, socket extensions that you find necessary, in combo with the appropriately sized socket swivel, to get your socket onto the KS bolt.
Patience and persistence are a virtue but it truly works … I’ve done it a number of times over the 25 years I’ve owned, driven, serviced and repaired my 4th Gen.
#4
Having someone with very small hands is the best option and using multiple extensions and a swivel/u-joint. It can be done without having to remove the intake plenum. Its only a single bolt that needs to be removed, good luck.
#7
That 300zx meme got me... so true.
Regarding removal of the knock sensor, especially if it's original, you may find that it's quite seized, and you may or may not have success with the universal joint method. With this method there's also a non-trivial risk of bolt head rounding if you're putting a lot of force on it and the socket slips (translate, plenum removal in your future). At a MINIMUM you should liberally soak the bolt and bottom of knock sensor (where it meets the block) with PB Blaster and let it sit for a while BEFORE attempting removal. For me, the SAFEST and most effective method for breaking this thing loose if it's really stuck has always been the 12mm box end and pry-bar method. Here's an oldie but a goodie, showing the technique:
Once you break it loose, any variety of 12mm long-reach articulated ratchet wrenches or extension/swivel head will make quick work of removing the bolt the rest of the way.
A wrench like this is worth its weight in gold for such a task as this, and also for re-installing.
Also, a flat head Jewler's screw driver or small pick will make easy work of the metal retaining clip at the sensor. It'll be obvious why, when you look at the connector.
I'll also comment that I recently picked up a minty-fresh, freak-of-nature '97 i30 with only 100K miles. I truly do not understand how this thing exists, as there's not a single dent in the body, and the leather looks, smells, and feels new. Truly an anomaly, but I digress. Everything in the engine bay was original, and so it had the to-be-expected hard and leaking valve cover gaskets, but beyond that, the ONLY issue that existed was a persistent P0325 code (which does NOT trip a check engine light BTW!). All other sensors (02 and otherwise, were functioning normally). I say persistent because I could reset the error codes using an OBDII reader and the P0325 would immediately return.
Don't bother with any other "cheap" sensors, just go to RockAuto and pay $38 bucks (plus shipping) for the NTK (part no. ID0139), also on Amazon for about the same $. This was literally the factory part with the little Nissan symbol "tactfully" ground off so as not to be sold by a dealer. Anyway, upon removing the old and measuring with an ohmmeter, I was initially confused since it would show good with 550KOhms, but then subsequent measurements would show high impedance (not completely open circuit). Eventually with some good connections between the meter and sensor, I could put an ever-so-small twisting force on the sensor and watch the Ohms switch from normal to BAD. In other words, there was an intermittent failure. The car's P0325 code, when not occurring with any other code, should be trusted, even if a meter happens to show a good reading.
I'll also just point out (having never seen it mentioned before) that even though the knock sensor has TWO metal contacts inside the connector receptacle, only ONE of those contacts is used. The wire harness is literally a single wire to that connector. The RETURN path for the circuit is through the metal base of the sensor, as it makes contact with the block. Consequently, make sure that this interface is CLEAN and that there is no debris getting between the sensor and the block when you re-install.
Lastly, and most importantly, the car now has what I would call "normal" power and MUCH better throttle response. A full tank of around-town driving with the BAD sensor yielded 20.5 MPG. A full tank (premium 93 in both cases) with the new sensor, and identical driving patterns, yielded 23.5. If the car "thinks" that the knock sensor is not in the circuit, it will resort to "safe mode" driving with overly retarded timing to prevent pre-ignition (pinging) damage. Sure, it'll drive without the sensor, but it's nowhere near as nice as with the sensor functioning. I can't tell you how many times I've seen a post on this forum saying something to the effect of "don't bother replacing it; it doesn't do anything, etc." Granted, this car was the ideal test case with everything else in tip-top shape EXCEPT for the knock sensor, so there may be some situations out there where this same improvement may not apply. However, as a general rule, replacing a bad knock sensor should result in a noticeable performance improvement.
Replace, run 93 octane, and enjoy!
Cheers
Regarding removal of the knock sensor, especially if it's original, you may find that it's quite seized, and you may or may not have success with the universal joint method. With this method there's also a non-trivial risk of bolt head rounding if you're putting a lot of force on it and the socket slips (translate, plenum removal in your future). At a MINIMUM you should liberally soak the bolt and bottom of knock sensor (where it meets the block) with PB Blaster and let it sit for a while BEFORE attempting removal. For me, the SAFEST and most effective method for breaking this thing loose if it's really stuck has always been the 12mm box end and pry-bar method. Here's an oldie but a goodie, showing the technique:
A wrench like this is worth its weight in gold for such a task as this, and also for re-installing.
Also, a flat head Jewler's screw driver or small pick will make easy work of the metal retaining clip at the sensor. It'll be obvious why, when you look at the connector.
I'll also comment that I recently picked up a minty-fresh, freak-of-nature '97 i30 with only 100K miles. I truly do not understand how this thing exists, as there's not a single dent in the body, and the leather looks, smells, and feels new. Truly an anomaly, but I digress. Everything in the engine bay was original, and so it had the to-be-expected hard and leaking valve cover gaskets, but beyond that, the ONLY issue that existed was a persistent P0325 code (which does NOT trip a check engine light BTW!). All other sensors (02 and otherwise, were functioning normally). I say persistent because I could reset the error codes using an OBDII reader and the P0325 would immediately return.
Don't bother with any other "cheap" sensors, just go to RockAuto and pay $38 bucks (plus shipping) for the NTK (part no. ID0139), also on Amazon for about the same $. This was literally the factory part with the little Nissan symbol "tactfully" ground off so as not to be sold by a dealer. Anyway, upon removing the old and measuring with an ohmmeter, I was initially confused since it would show good with 550KOhms, but then subsequent measurements would show high impedance (not completely open circuit). Eventually with some good connections between the meter and sensor, I could put an ever-so-small twisting force on the sensor and watch the Ohms switch from normal to BAD. In other words, there was an intermittent failure. The car's P0325 code, when not occurring with any other code, should be trusted, even if a meter happens to show a good reading.
I'll also just point out (having never seen it mentioned before) that even though the knock sensor has TWO metal contacts inside the connector receptacle, only ONE of those contacts is used. The wire harness is literally a single wire to that connector. The RETURN path for the circuit is through the metal base of the sensor, as it makes contact with the block. Consequently, make sure that this interface is CLEAN and that there is no debris getting between the sensor and the block when you re-install.
Lastly, and most importantly, the car now has what I would call "normal" power and MUCH better throttle response. A full tank of around-town driving with the BAD sensor yielded 20.5 MPG. A full tank (premium 93 in both cases) with the new sensor, and identical driving patterns, yielded 23.5. If the car "thinks" that the knock sensor is not in the circuit, it will resort to "safe mode" driving with overly retarded timing to prevent pre-ignition (pinging) damage. Sure, it'll drive without the sensor, but it's nowhere near as nice as with the sensor functioning. I can't tell you how many times I've seen a post on this forum saying something to the effect of "don't bother replacing it; it doesn't do anything, etc." Granted, this car was the ideal test case with everything else in tip-top shape EXCEPT for the knock sensor, so there may be some situations out there where this same improvement may not apply. However, as a general rule, replacing a bad knock sensor should result in a noticeable performance improvement.
Replace, run 93 octane, and enjoy!
Cheers
Last edited by pethelman; 02-13-2024 at 07:36 PM.
#9
If not, get some 1/4 swivel sockets, 24 inch 1/4 extension, and 1/4 ratchet. Your first time you'll need patience, a flashlight, and some imagination.
Disclaimer, the first time will likely take you over an hour lol
#10
15 minute job.. I used to do these left and right super cheap for other org members in Chicago back in 2008-2012s lol. If you're in Chicago, I might even have some bulk knock sensors left over and able to swap it out.
If not, get some 1/4 swivel sockets, 24 inch 1/4 extension, and 1/4 ratchet. Your first time you'll need patience, a flashlight, and some imagination.
Disclaimer, the first time will likely take you over an hour lol
If not, get some 1/4 swivel sockets, 24 inch 1/4 extension, and 1/4 ratchet. Your first time you'll need patience, a flashlight, and some imagination.
Disclaimer, the first time will likely take you over an hour lol
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