I changed out my knock sensor last night. I reset the ECU and went for a drive. The car is SO much smoother now. Before whenever i was accelerating moderately the engine would seem a little rough. Now it just purrs and pulls so much harder. My low end power is back and the high end has much more pull. The difference is huge! I am very happy. Anyone with the 0304 engine code needs to change out their sensor. Hello better gas mileage. Maybe now I can break the 14's.

 

Thanks for the input, I have the same code, my power is awful now and I have jerky acceleration when I am light on the trottle. When JMAXIMA and I used to race it was dead even but now he pulls on me especially in 3rd. I probably need a fuel filter and TBI cleaning as well, I just don't have the cash for any of that now!

 

the check engine light would come on if the knock sensor needed to be replaced correct???

 

NO, the Knock Sensor is the only sensor in the car that will not trip the light...

 

so how do i find out if it needs to be replaced??

 

when my knock sensor went out .... my light went on. I had no other errors on my system .... the cheapest price I found was at the partsbin.com for ~$115 or so..................

 

Run your ECU..if code 0403, I believe, is displaid then you need to replace it...Does your car feel sluggish ??

 

yeah it does feel sluggish...how do i run the ECU???

 

http://forums.maxima.org/showthread.php?threadid=104931

 

A bit OT I know, but the above is incorrect. My SES/CEL didn't light
up even though I had a bad neutral/reverse sensor. I ran the ECU
scan manually, per the Hayne's manual, and got the neutral/reverse
code. I changed it and voila, my idle returned to normal and I no
longer had the RPMs rising every time I came to a stop.

Anyhow, the short of it is that several sensors won't cause a light
upon failure, but they will register in the ECU.

 

The knock sensor code is 0304.

 

do you need to reset your ecu when u replace the knock sensor?

 

You need to reset it anytime you (hopefully) fix the problem. This will probably be a good indicator for me wheather or not the knock sensor code(0304) is actually a "ghost code". I plan on seriously tuning the car up, fuel filter, TBI cleaning, and plugs before I change the knock sensor. My car has 55k and I plan on doing all of these things before I change the knock sensor. One of my theories is that I have a misfire due to an injector that is clogged or not giving a good spray pattern. I have no idea what kind of gas was put in before I bought it(28k, every gas has detergents but some not as many as others) but the injector theory is a longshot. Another theory, of course is the plugs, even though I have gone to the track alot a doubt this is the problem i.e. heavy acceleration(even though I am too lazy to inspect them for deposits etc.). So finnaly this leads to either a nasty TB, fuel filter, or of course the knock sensor. As far as I am concerned it is a combination of everything, to a greator or lessor degree, and trust me everyone....I will include a write up if needed for each time I change or fix one of these parts...just let me know.

P.S. I need to get out of debt first which will happen in two months at the VERY latest. I know alot of you guys have read about my problems in the past...I promise I will find exactly what is wrong with the ride....and btw I have a speed sensor code as well; any input would be nice. If not I will buy a Haynes manual.

 

I've had cold engine idle surge problems
for last summer and this one also.
Cleaning Throttle Body was a help, but
Knock Sensor code appeared after
cleaning TB this summer. I like the theory
that it's a combination of factors that
cause hesitant accel at 1500-2500 RPM
on a cold start and sometimes (5-10% of
cold starts) surge at idle. My question
is how easy is it to replace the knock
sensor and where would be a good place to
get one? How much do shops like Pep Boys
(or dealer) charge for doing the job?
Thanks

 

You can do this replacement yourself.
http://forums.maxima.org/showthread....t=knock+sensor

 

I'll let you in on a little secret. I have been trying for a while to win a knock sensor for my 4th gen on ebay for $75 or less, but had been unsuccessful. Completely by mistake, I bid on a KS for a 5th gen Maxima, which I won for $25.

When the KS arrived, I measured the resistance, which came out to ~550 kohms, same as for the 4th gen. The only apparent difference was the connection to the harness. So I modified the harness to fit the 5th gen KS and installed it.

It works perfectly - low end power is back, smooth acceleration, etc.

I've noticed that the 5th gen KS seem to go for much lower prices on ebay than the 4th gen KS, probably because of reduced demand. So you might want to give it a try.

 

I went to a local place where u can buy used parts from them and the guy didn't even know what it was, he asked me how much the knock sensor was new and I'm like "like 80 bucks" he said "I'll give it to you for 40", hehe, so I'm picking it up today

question, if the 550kohms resitance with the engine running not? can you check this resistence while the sensor is out of the car?

thanks for the info, hopefully my knock sensor problem goes away

 

Check the resistance with the engine off. Yes, you can check the resistance with the KS out of the car.

Be aware that knock sensors can display intermittent failure behavior. The first time I checked my KS resistance, it showed an open circuit. So I pulled the KS out, checked it again and what the ****, it's showing 550 kohms. So I put the KS back in after sanding the contact surfaces of the KS and the engine, thinking that maybe it was a contact resistance buildup between the KS and the engine. But my car never really seemed to be running as good as it should, and I checked resistance again and it showed up open circuit.

So I made up a faux-knock sensor with a couple of resistors from Radio Shack to give me 550 kohms and plugged that into the harness instead of the KS. That way the engine would think it had a normally operating KS. Voila! An immediate increase in performance. That pretty much determined that either the KS or the KS harness was the problem. I checked out the harness thoroughly and it showed no problem. Eventually I got a new KS, and the problem is solved and the car is running as it should now. Yet, after I pulled out the old one, it checked out OK once again! Weird.

 

any recomendation for checking a used (faulty) KS if it shows a 550kohms? hopefully this works, I called them up and they said that they have my part, if not I'll make them replace it, otherwise me calling my credit card and cancelling the charge and they'll be screwed

 

allright, so I got this knock sensor, and I'm trying to get the resistance on the sucker and it's only showing like 20 kohms, vs. the old one (it was cracked by the way) was showing like 13 kohms

i checked the codes and it gave me nothing, (it did give me 0505 which is "No Failure Recorded/Detected")

so I don't know what to think now, the resistance is wrong but the ecu doesn't throw out a code, I went for a drive around the block the car feels like it has more power in 2nd gear now, where before it felt like a dog.

 

As long as you aren't getting 0304 and the car feels like it has good low end power and smooth acceleration, I wouldn't worry about the resistance reading. But how were you measuring the resistance? You should have one lead at the pin going into the KS (there are two pins, but only one is used) and the other lead on a good grounding location or on the metal base of the KS. And you should be using a good digital multimeter, too.

 

yeah, that's what I did, one on the ks wire and one on the negative side of the battery I'm going to check my friends max resistence, maybe I'm just doing it wrong

 

What kind of resistors did you use and is this a safe idea? I need a KS but I can't afford to buy one right now, my cash flow is severly low, which really sucks! I should be able to afford one in a few weeks though, hopefully.

 

Just curious, what octane of fuel have you gues been using? Nothing but 93 octane in my 95 max with 192,000 miles, and no problems with KS.

 

how much