my car threw the 0304 code.....i'm just asking if these following things are symptoms of a bad knock sensor: struggles to start sometimes(but always starts), bad gas mileage(only about 220-230miles out of a tank, i used to get 300+),hesitates to move at low rpms, but once i get over about 2000 the car takes off. is this all from the knock sensor or something else is wrong? also where is there a place to get these sensors cheap

 

Sounds to me like a typical KS failure. http://www.nissanparts.cc/ provides KS for around 120 plus shipping.

 

there is a very low key site out there that i got mine for 100 shipping included... keep it quiet... its www.ebay.com

 

Are there any other codes in addition to 0304? You should fix those first before changing the KS. As far as gas mileage, a bad KS reduces mileage by about 10%. I just changed mine and get 25 MPG compared to 23 before the change (50/50 City/Hwy). This is just my experience. Your milage seems to be very low, do you always fill up the gas tank? How many gallons go in?

 

i checked the codes when i was doing my intake, b/c i forgot to reattach the air temp sensor and my engine light came on, so i got that code and the knock sensor also. so right now its the only other code. i always fill the tank up with at least 89 but usually 91 octane. usually about 15 or 16 gallons go in. i just put that fuel injector cleaner in my car last week too, and it helped the mileage a liitle bit. i got about 215 miles before the cleaner, last time i got like 230. this time im on pace to be about the same, maybe 240.

 

IMHO when you have a bad ks you loose a lot, Gas mileage, and power! The power issue really sucks hard. its like a 20-45 hp deficate. Man My car has all these problems, I think Nissan should Issue a Recall on 99 Maximas casue they always get a Bad KS issue

 

i got my KS for 100 bucks installed.i work at nissan.

 

i swear you lose like 15-20hp (butt dyno) just from a bad KS alone...

mine went bad and i had TERRIBLE LAG!!!

finally I changed it and i got instant trottle response! it was awesome!!!

then my car felt VERY slugish again...

turns out i hadn't screwed the KS down properly...

I was actually able to instantly tell the difference. and I was even able to tell when i lost it.... I was driving down the road when my cel light turned on... I was like what now??? and my throttle response sucked and i felt my car slow down a bit...
It was odd. I wasn't sure what was going on at the time!

 

i also have bad gas economy and my car seems 2 be slow around 3k, but as soon as im over 3 k, it takes off. I get like 120 to a half tank, maybe more. It really sucks. I used to get around 180 or so. I have no codes, and no ghost codes as well. Plugs have been changed 10K ago, and TB cleaned as well along with the Fuel filter. Could it be the KS?

 

I have the same problem as superfishstick. One thing that I noticed when cleaning my intake was that right beside where one of the four bolts go in, the plastic was cracked all the way though....I glued it back together and it seems to be holding fine....I am not even sure if this would create a problem because it was cracked above where the gasket seals the MAF. I am not throwing any codes nor a ghost code...I was wondering the samething....is the the KS? Oh yeah, I have cleaned the TB, replaced the fuel filter, and my air filter is clean....

 

You lose about 20% of power and your gas mileage is cut by 30%+. A KS will not trip your CEL so multiplexor you have other problems as well. As a matter of fact I completely disconnected my KS from the harness and drove around, absolutely no difference in performance and the CEL didn't go off. If your not sure if the KS is messed up just disconnect it...

 

just did the same thing this saturday...haven't cleared it yet...will do tonight...i'm having a feeling that my ks might be bad too...but i'll disconnect it to check it out....but then again it might be in my head because it seems like a lot of people are talking about the ks lately.

 

How did you change the KS ? Did you have to take the i/p manifold off like the manuals detail ? I hope that I never have to do that. Too much for me, and looks very expensive to outsource it.

 

there is also another way, u need a ohm meter and u check the resistance. I should do it, as soon as i get an ohm meter....

 

very true but....there have been cases where the reading is ok but the ks is still bad.....i just saw someone say that about theirs in another thread a couple days ago.....so be careful with that because even though you'll get a good reading your ks might still be bad.

 

just went to see if i can disconnect my KS and see if there is a differece. The car was still too hot, especialy near the lower intake manifold, and my hands are tooo big to fit in there and disconnect it.... i'll give it a try later on.

 

DOESN'T ANYONE READ WHAT I WROTE???

Fishstick the harness is not under the manifold, just follow the line to a connector on the left of the TB, it's small and black..\

I have an ohm meter fishstick. The ***** cost like a $100, I'll borrow it to you if you want. I just checked my KS and it was 470k ohms, that makes me think that it's just not tightly screwed in. Unfortunately my garage was robbed(by my neighbor but I have no proof) so all my tools are gone and I can't tighten it...

 

The ks wire has clips at both ends, so you can unclip it where it attaches to the main harness around the throttle body area. Just follow the wire up from the ks and you'll see. Also, you can sub a 560k ohm resistor between the main lead of the harness and ground. The spec for a good ks is 500-620k ohm, so 560k puts you right in the middle.

 

There was a very good thread on how to replace the KS without removing the intake manifold a couple of months ago. Should take 30 - 45 minutes. I used a similar instruction and was able to replace mine. It took some time but was fairly straightforward.

 

thanks... i thought i had to check the KS its self. That would be kind of tough. I'd like to borrow the ohm meter one day, right now, i'm just too busy. Thanks for the offer man. Really appreciate it.

 

http://www.motorvate.ca/mvp.php/507

thats the site where it shows you how to replace the knock sensor without removing the air filter. however there is a real small space so u'll need really small hands.

 

Is this true? I have heard everywhere from ranges of 15-45hp loss in this thread alone. Most a say about 20hp. 20% of 190 (stock HP) would be almost 40hp. I bought my car about three mounths ago and recently found out that the ks is shot (prob scince I bought it cause the last owned used $h!tty gas.)

Hey, this is more than any other $100 mod!!!
I got to go do it!!!

P.S. When your as poor as me, things like starters and KS's count as mods (till I save up some money).

 

so what is the best thing to do? check for codes, use ohmmeter, or just disconnect it?

 

can u drive around without the knock sensor connected? what happens to the car if you do this

 

you mean disconnected? If it's bad then it will drive the same, if it's good then the performance will drop...

 

from what i understand,you didnt feel a performance difference when the KS is hooked up and unhooked?if you had a bad KS already then regardless of being hooked and unhooked,you wouldnt feel a difference.its like taking off thats something bad already. $0.02 worth

 

I should have also noted that i am having an EVAP problem and a rear o2 sensor problem... hehehe

But both do not affect performance...

the incredible lag and lack of power pointed me to the knock sensor...

I would take off and have super lag!! could even spin out much!

now from a rolling start i can gun it and lose traction in first gear till redline!!

 

personally I would either remove it and ohmmeter it.... or try from the harness...

hell you could always just get lazy and disconnect it...
then go for a drive, and really drive the car hard... Personally... and this is personally! I found that the ecu adapts really fast when your hard on the car!

It would only take like 25 miles before my cel light would turn on again. whereas other times when i'm soft on my car, it would take like a week before i got the cel....

 

You will loose considerable power below 3000 RPM, but my mileage went from 25MPG to 27MPG (80% highway miles) when I replaced the bad KS. Nothing close to 30% loss based on my personal experience although I am sure it is possible if you do a lot of aggressive stop and go driving.

 

I'm getting a 0702 code (Three Way Catalyst (right bank))
AND the 0304 KS code.

What the hell is Three Way Catalyst (right bank)?? I'm hoping that whatever it is, it's triping the KS code.

 

There were so many posts regarding the KS...Is not hard to do,if you ve got small hands...It took me maybe 15 min to change the KS. The gas mileage would decrease quite a bit. Also, remember that many emission problems decrease the gas mileage. I have a recent o2 sensor heater code, and decided to check it because my mileage went down a bit.

 

What's the point of this reply? I said I disconnected it to see if there was a difference. There wasn't meaning the KS is broken...