i finally replaced my knock sensor and the improvement in acceleration is huge. i tested my old sensor and there was no
circuit going through at all. now my car finally feels like it should since lately it has been feeling very sluggish.

it only took me about 15-20 minutes to install it, and my hands are still all in one piece. i've been looking at how people have done this and noticed that people used flex sockets and extensions. i just used a short 12mm socket and a very small 1/4" drive rachet wrench. and most importantly, use your left hand to get in there, i could not get my right hand in there for the life of me.

 

since the knock sensor had no circuit running through it, did the CEL light up?

 

Im wondering the same thing. How do you test the knock sensor anyway?

 

get a voltometer, and then stick the leds into the wiring somewhere, and then see what the reading is....i dont really know what its supposed to be in between, but if you search, you can get definate answers

edit: it is confirmed (atleast by me and some other folks), that the knock sensor ALONE doesn't trip the CEL....if say your MAF goes, that will trip it, and along with that will come the KS code.....if you fix your MAF, and reset the ECU, if you go to diagnose it, itll most likely still have the KS code

 

Good to know that the KS sensor alone will not trip the CEL. I will have to look into it and make sure its still good.

 

You know...the more I think about it, the less I understand about knock sensors based on forum members' experiences. i.e. If the knock sensor sends a "signal" upon detection of engine knock/ping - at which point, the ECU retards the timing, which also results in decreased power - doesn't it stand to reason that a non-functioning knock sensor would only result in [audible] engine knock and have no effect on timing or power? It would make sense that the ECU would respond if there were erratic signals...But why would it respond if there were NO signal?

 

When the ECU senses a problem with the KS it goes into a closed loop. This in effect is "Safe mode" for the ecu. The timing is retarded and the loss of power is noticed. In other words, it won't allow the car to advance the timing and cause any knocking with a bad KS.

 

It's a failsafe mode. If the knock sensor completely fails, the ECU is programmed to implement maximum timing retard to avoid any possible engine damage. The knock sensor is there to protect the engine. If it doesn't work, the ECU needs to kick in and protect the engine.

Fail safe mode is a very common programming practice...industrial machines, etc.

 

Finally...Closure...I feel much better about having ordered a new sensor. Thanks for the lesson folks.

 

HOW did you test it with a voltmeter? If you try to test the 2 leads going out there is gonna be an open circuit. The right way is to ground one of the multimeter leads and then connect the other to the lead that is closer to the front of the car. Then it should read in the 560K ohm range. My KS passed the resistance test and did not throw the 0304 code. However just because the KS passes the resistance test does not mean its 100% good.

 

One other thing - since a bad knock sensor itself won't trip the CEL light, you can test it through your ECU. Here's a link which shows you how to test your ECU without paying a mechanic $70 or more to pull your codes, or buying an OBD II diagnostic tester:

http://vbxmaxima.8m.com/ecu.html

In a nutshell, your ECU can transmit codes as flashes of the CEL light. This link tells you how to do it, and also how to decipher what the codes mean. If your knock sensor is bad, you should get code 03 04. Again, a bad knock sensor in itself won't trip the CEL.

 

Welcome to last week...

 

Note: It's probably a statement of the obvious to you veterans, however...The code manually retrieved from the ECU should not be confused with the ISO 9141 defined codes typically displayed on a scan tool. e.g. P0304 = "Cylinder 4 Misfire Detected". Scan tool displays of knock sensor codes range from P0325 to P0334.

 

I just found out I need a KS sensor also. So where did you buy yours?...how much?

 

how much is a new knock sensor and where can i get one?

 

I'll admit - I couldn't remember where I saw it, until right after I posted it....after digging for it, I didn't want to delete it. :::banging head on desk::::

 

i bought mine at a nissan dealer for $164... but several people are selling them on this board for cheaper, i just didn't want to wait for one to come in the mail.

 

did replacing it improve power over the whole power band or just top end??

 

I just ordered one from nissanparts.org (Pinnacle Wholesale Parts Warehouse) for $126 plus s&h.

 

your nissan dealer, or www.courtesynissan.com has em for like $109 or someting along the lines of that

 

How many miles are you car before you decided to change this?

 

More like $139.80.

 

Hey there, just reading up on this whole knock sensor thing. I have a 5'Th gen 5 speed. Someone said something in regards to being able to somehow advance the timing positioning by setting the KS In a certain way. Any validation to this without useing an OBDII. My local shops will not advance my timing. Im In Westchester NY, If so, please share step by step.. Thanks.

 

the knock sensor isn't all thay hard to swap but after trying various ratchets with swivel heads and what not the only thing that worked for me was a girl with very small hands. The knock sensor doesn't need much torque (20 foot pounds) so its all about access. My huge gorilla mitts just were not working.

 

First of all, why did you bump a 7 year old thread, in the wrong section?

No, you can't 'advance the timing' by changing the position of the KS. That's just ridiculous.

You can have it advanced with a CONSULT-II or equivalent.

In the future, use the newbie thread, that's what it's there for. Do not bump 7 year old threads that aren't even relevant.

 

man i need to get off my *** and change mine.
my new knock sensor has been sitting in the glove box for nearly 2 months now........

 

 

i got the p0325 code...i have been having issues with my car stalling out...it is very randomly...mostly at lights or whenever the rpms are low...if i can accelerate before the idle starts bogging, it will even out then at the next light it will stall...takes forever to crank back up,,,what is this...could my knock sensor be causing this???i let it stall out infront of my house and it thru the code p0125...What do i do???

 

No, it's not the KS.

Well did you even look up the code you got?
Code: P0125 | Description: Engine Coolant Temperature Sensor


The ECTS can cause stalling problems. Test it, the harness, and replace/repair if necessary.

 

Thanx pmohr...i actually did look up the code but i didnt know if it would cause my car to stall ...i appreciate the closure...also, i tried to unplug my MAF to see if it would smotthenthe idle out...it actually made my car produce the same problem it gives me at stoplights...it just ends up bogging out...but when i plug it back in it dies out...