all i can say is HOLY ****!!! i knew my max wasnt pushing as much hp as it should have been (ever since i've had my sc) and i couldnt figure out what it was. anyway, ever since i've had it, when i run diag on my ecu, it give me a k.s. code. so i've finally decided to replace it. after i finished last night, i went for a ride. i was cruising at about 10mph in 1st gear, and stomped the pedal to the floor. i spun all the way through 1st gear, then spun half way through 2nd!!! i dont understand how the k.s. being bad could rob that much power from me, but i guess thats why i'm not a nissan tech gotta get back to the track!!!

 

how you changed it out. i think i have the same problem, cause my car is really down on power.

 

How much is a knock sensor anyway? Do you just get it from the dealer?

SuDZ

 

its fairly easy if you have small hands. the ks is right under the manifold, you have to have a flash light to see it. get a 12mm socket and wiggle your hand in there and take off the bolt. the ks will come right out. unhook it from the harness, hook the new one up, and bolt it back in. it took me about 15 minutes and only 1 scratch

 

i think their about 200 bucks from nissan, but i got mine for 75 from someone on the board

 

Other than the small hands part it seems pretty easy. Does the ECU through a check engine light if your in need of one or do you just have to check the ECU to get the code?

SuDZ

 

The ecu will give you a CEL and when you pull the code it will tell you. The KS is actually pretty delicate diagnostic part. I have read in the forums that, and it's also a part that some people say needs replacing after a while. It can get tripped by simple things like bad gas (causing pinging) and even CAI installs by the fact that sometimes trips the O2 sensors and the KS sensor together.

 

most of the time the ks wont trigger the CEL. mine never came on, but when i ran diag on the ecu, it would through the code out.

 

Right, what I was trying to say was that sometimes when the O2 sensor is tripped it will also give you the code for the KS.

 

I think it's time to replace mine, its the 3rd week in a row that it;s thrown the k.s code at me, where exaclty is it under the intake manifold?

 

It's right under the intake manifold. It looks like a little metal top. If you look from the battery side of the car, straight across the fender well under the manifold and little to left, that's it. (How'd yall like those directions). BTW I too have a pebble beige 95.

 

its pretty much the only thing up under there that is bolted down and has a harness running to it. get a flash light and shine it under the right side of the i.m., and it is dead center of the manifold.

 

This should help. It real easy to take out if your hands are small. But if they are not like mine. You need and extention to get in to there.


Posted by bill99gxe on 08-02-2001 04:21 PM
DTC 0304
Diagnostic Trouble Code 0304 points to a problem with the Knock Sensor. The KS
is attached to the cylinder block. It senses engine knocking using a
piezoelectric element. A knocking vibration from the cylinder block is senses as
vibrational pressure. This pressure is converted into a voltage signal and sent
to the Engine Control Module (The computer).

This malfunction is detected when an excessively high or low voltage from the KS
is entered to the ECM. Possible causes include...
- the harness or connector (The KS circuit is open or shorted).
- the KS

The KS may be checked with an ohmmeter.

1) Raise the hood. View the engine from the driver's fender. Look into
the deep valley between the cylinder banks and below the intake manifold.
Identify the KS as a black item fastened to the block by a single vertical
bolt. A wire harness wrapped in black leads toward you, out of the valley.
That is the KS sub-harness.

2) Follow the KS sub-harness to it's nearest connector. This is connector F121.
It is located near the upper right-hand corner of the valve cover of the forward
cylinder bank, as viewed from the front of the car.

3) Disconnect F121. You have to do a "press the latch and wiggle and
pull" to disconnect it. F121 has only two pins; if you see more than two
pins, you have the wrong connector. Use a digital ohmmeter capable of
measuring more than 10 Megohms. You want to measure the pins of F121, not
the sockets of the matching connector. Measure the resistance between a
good ground (such as the battery negative terminal) and pin #2 of connector
F121. On my car this is the highest of the two pins, the one closest to
the front of the car. The factory spec is 500 - 620 Kohms.

The manual says you have to remove the intake manifold to replace the KS.
However, I think that a person with good dexterity and a 10mm ratcheting box
wrench could replace the KS without disturbing the manifold.

 

well i guess its about time i stop ignoring that k.s. code i also got a vehicle sensor code which i think is the reason my speedometer stickes from time to time.anyone one from here replace v.s.s on their own?

 

I just replaced my KS also and noticed a huge power increase . I have a 3rd gen SE so I had to take the entire intake manifold off to get to the sensor, but it was well worth it. It turns out that the connector at the sensor was all corroded and not making contact anymore. The old sensor still works after cleaning it up, but I put the new one in anyway. I ordered the KS through Courtesy for $135.

 

This may be a stupid question but you do the test with the engine running or not ??

 

Huh. I dont get a check engine light or anything but maybe one day I will check the ECU to see if I get a code from anything. It could be one of those things that if needed I guess I will go for. Good to keep in mind anyhow.

SuDZ

 

Okay one more question. Is there a way to visually tel if your in need of a new sensor. Like if I took it out to inspect it can you see and defects or what not that would lead you to believe you need a new one?

SuDZ

 

to tell you the truth, when i pulled my old one out, i couldnt tell the 2 apart.

 

i had the 0304 knock sensor code for a while and decided to replace my KS last week. I definitely noticed better performance(especially in the higher RMPs) and kinda solved my ****ty gas mileage problem. I ordered through a friend of mine and got it for $140 but i found a better deal at this site for $128:

http://www.nissanparts.cc/partsearch...ber=2206030p00

My old KS kinda threw me off because it gave a reading of 5MOhms then after awhile it would be the normal ~550kOhms. I think the piezo element inside wasn't behaving consistently, throwing weird voltages. So if your KS tests OK but you still have the problem, you might want to check it a couple times. I did the test on my brand new KS and it gave a reading of 550kOhms consistently every single time i tested it. Also, i was able to change the KS without removing the intake manifold too. I just used a 12mm socket w/ and long extension and a universal joint. then i stuck my "little hands" up in there and unscrewed the rest. One last suggestion, WEAR A THICK RUBBER GLOVE OR SOMETHING cause the f$#cking sharp edges in there shredded my hands up!!

 

Cool thanks guys. Maybe I will test the ECU and check the KS one day. I dont think I have any problems but like knowing that if I did I would be able to find out before anything worse seemed to happen.

SuDZ

 

this should be a sticky.

 

this should be a sticky.

 

Is there any sign that can tell you the knock sensor need to be replaced? Like the way your car is running or any abnormal sound for example? My car is running pretty good, the only questionable item is the tranny.

 

I started to notice a lag in power, and also the 1st time I ran at the track I ran a 15.4 w/ my sc. I ran a 15.6 at maxus and I KNEW something was wrong, just couldnt figure out what. I also noticed that at low rpm's in 3rd and 4th gear (while accellerating) the car would lag.. almost like it was shooting fuel in spirts, and not a smooth flow. hope this helps.

 

How long do they last? Is it somethign that needs replacing eventually or is it just some last some dont?

SuDZ

 

Yes, Thanks.

 

that's exactly what I was looking for, I have the same problem, i guess I need to spend some more money

 

Huh, If I check mine out and find out I have been losing power in it then maybe my et times will lower. Or maybe I will find out it is fine and it is just me

SuDZ

 

Some ppl on here have noticed nearly a second of their 1/4 mile times

 

Seriously? That's f'n HUUUUGE. -Anyone here vouch for that? Maybe I'll be pulling codes this weekend. . .(That's all I need - spend more $ I don't have!!!)

 

i feel ya samething here.

 

heres the real question.....can their be something wrong with your knock sensor and your ecu not pick it up? with an intake and a cat-back exhaust i manage only a 15.6 in a 5 speed......

 

Herre's the thread

https://maxima.org/forums/showthread...5&pagenumber=1

 

???

 

Not yet, still need to figure out the vacuum lines. I may just buy a PR or WSP upper tube.

U still like yours?(or lack of res. should I say)

 

That was me.

To clear things up, no, you won't get a CEL, but it will show up as the 0304 on the diagnostic. You can test the part, but a bad sensor may still test within spec. Its a solid piece of plastic with a bit of metal running through it, so you can't visibly inspect it and tell if it is bad. Yes, you can replace it yourself. It is located directly underneath the center of the upper intake manifold, is held on with ONE 12 mm bolt and if you have small hands, can be taken of without moving the intake manifold. The part is about 140 from the dealer. As for the drop of 1/4 mile times, it took 1.1 seconds off of mine when I replaced it, so it HAD to be retarding timing. THIS DOES NOT MEAN THAT CHANGING IT WILL MAKE A CAR RUNNING 14s INTO A CAR RUNNING 13s. If the KS in your car is fine, it will not lower your time.

 

i must have to replace mine i have definatly noticed a loss in power.

 

Is it something I have to replace eventually or if its good then dont bother with it??? Thank you

 

i wouldnt mess with it unless its bad.