96 SE Knock Sensor - Nissan Forum

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post #1 of 22 Old Aug 25th, 2005, 11:07 AM Thread Starter
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96 SE Knock Sensor

Can anyone give me an idea why the knock sensor would continue to go out on a 96 SE Pathfinder? I replaced it once then the next day same problem and the code thrown was for the knock sensor originally and then again.
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post #2 of 22 Old Aug 25th, 2005, 12:04 PM
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Just a guess, but maybe the replacement part was defective.
BTW, is the code indicating the sensor is bad or that the sensor detected knocking?

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post #3 of 22 Old Aug 25th, 2005, 12:28 PM
b67
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Quote:
Originally Posted by squeezinSE
Can anyone give me an idea why the knock sensor would continue to go out on a 96 SE Pathfinder? I replaced it once then the next day same problem and the code thrown was for the knock sensor originally and then again.
ignore the knock sensor if your CEL is off unless you feel/hear knocking

Do you do alot of short distance city driving?
post #4 of 22 Old Aug 25th, 2005, 03:49 PM
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It may be related to the evap canister / vent control valve (forgot the exact name if thats not it) Could be carbon buildup on throttle body as well - others have experienced this though I have nver cleaned my TBI in the life of my 99
post #5 of 22 Old Aug 29th, 2005, 01:15 PM
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Knock Sensor

220k miles and my path knock snesor is great but it pings like a bag of tin cans for no reason other than i run cheap gas in it....
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post #6 of 22 Old Aug 29th, 2005, 02:24 PM
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Quote:
Originally Posted by architectdave
220k miles and my path knock snesor is great but it pings like a bag of tin cans for no reason other than i run cheap gas in it....
is it the 3.5? As I recall thats the one that needs high octane
post #7 of 22 Old Aug 29th, 2005, 04:45 PM
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Quote:
Originally Posted by b67
is it the 3.5? As I recall thats the one that needs high octane

It does stop with high octane but its the 3.3. I just turn off the over drive or get a few gallons of high octane when it does it. When i tow my boat i use a tank of high octane but thats twice a year once to the lake in may and once home on sept.

its annoying but the knock sensor is suppose to prevent that. its done it since it was new. Also what gives on the gas milage? My folks 97 Tahoe with a 350 gets better gas milage and its nicer to drive.....shakes my faith in nissan a bit
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post #8 of 22 Old Aug 29th, 2005, 06:47 PM
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Quote:
Originally Posted by architectdave
It does stop with high octane but its the 3.3. I just turn off the over drive or get a few gallons of high octane when it does it. When i tow my boat i use a tank of high octane but thats twice a year once to the lake in may and once home on sept.

its annoying but the knock sensor is suppose to prevent that. its done it since it was new. Also what gives on the gas milage? My folks 97 Tahoe with a 350 gets better gas milage and its nicer to drive.....shakes my faith in nissan a bit
Well, an engine that is knocking is not running efficiently. What mileage are you getting? Have you checked your timing?
Also, isn't the function of the knock sensor to detect knocking, not prevent it?

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post #9 of 22 Old Aug 30th, 2005, 07:19 AM
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Yes the knock sensor detects detonation but it then tells the ECU its happening so the ECU can adjust the fuel mixture, shift or retard the timing....

I get 19 or so miles on the highway with tires a little harder than they should be and a K&N filter MInd you thats driving 75-80. My Fiance's 2002 Deville with a 300+ hp Northstar v8 gets 22 My folks Tahoe gets 24-26..... that make much sense to you?

I drive my honda accord most days for the 32 i get

Last edited by architectdave; Aug 30th, 2005 at 07:23 AM.
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post #10 of 22 Old Aug 30th, 2005, 08:15 AM
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Quote:
Originally Posted by architectdave
Yes the knock sensor detects detonation but it then tells the ECU its happening so the ECU can adjust the fuel mixture, shift or retard the timing....

I get 19 or so miles on the highway with tires a little harder than they should be and a K&N filter MInd you thats driving 75-80. My Fiance's 2002 Deville with a 300+ hp Northstar v8 gets 22 My folks Tahoe gets 24-26..... that make much sense to you?

I drive my honda accord most days for the 32 i get
So the ECU must first detect the knock then attempt to de-tune the engine. It would be better if the engine didn't knock in the first place.
Are your measures in miles or kilometers? 19 MPG isn't bad at all if you are pushing 75-80 MPH. Other factors that could explain your findings include vehicle weight and driving habits. For example, I know I could get better mileage if my acceleration was slower and if I shifted at 3K-3.5K instead of 5K.

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post #11 of 22 Old Aug 30th, 2005, 08:30 AM
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Quote:
Originally Posted by Animal
So the ECU must first detect the knock then attempt to de-tune the engine. It would be better if the engine didn't knock in the first place.
Are your measures in miles or kilometers? 19 MPG isn't bad at all if you are pushing 75-80 MPH. Other factors that could explain your findings include vehicle weight and driving habits. For example, I know I could get better mileage if my acceleration was slower and if I shifted at 3K-3.5K instead of 5K.

Animal Im not sure if your asking me or if your question is rhetorical. From my minimal understanding and from owning many cars old and new, Back in the day before ECU's we used to advance our timing to get the most power from our cars and you would ride a fine line between cars than ran well all the time or detonated once in a while due to to mutch advance combined with bad gas or a hot day or carbon buildup in the combustion chamber. So when the Fuel Injection and the ECU came out in full force its my understanding that the engine adjusts its own advance injection pulse fuel/air mixture etc and to do that effectivly it needs to know if the engine is working properly with things live the knock sensor and o2 sensor and in older cars the mass air flow sensor etc... so to say the engine is detuning itself is relative to weather its tuning itself properly for every second its running.

As for my truck as time has gone on it has been more susseptable to pinging and im sure thats due to wear and tear as well as carbon build up etc. So it would be better if it didnt knock in the first place but with todays engines if it knocks then theoreticly its not doing something right. Maybe without 93 octane the limits of the system to adjust itself are breached and it cant do its job properly........

19 miles per gallon for a 3.3l anything seems bad to me - it always has and driving over 100 miles a day i have done the tests where i drive slower and accelerated slower etc. It fluctuates a little but not much. I love my path don't get me wrong but ive always wished it got better milage and for the record if i could have afforded twice the payment i would have gotten the Tahoe

Poor planning on your part does not constitute an emergency on my part........
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post #12 of 22 Old Aug 30th, 2005, 12:43 PM
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Quote:
Originally Posted by architectdave
Yes the knock sensor detects detonation but it then tells the ECU its happening so the ECU can adjust the fuel mixture, shift or retard the timing....

I get 19 or so miles on the highway with tires a little harder than they should be and a K&N filter MInd you thats driving 75-80. My Fiance's 2002 Deville with a 300+ hp Northstar v8 gets 22 My folks Tahoe gets 24-26..... that make much sense to you?

I drive my honda accord most days for the 32 i get
no way a tahoe will get near that mpg at 75-80mph. For the amount of fuel the 3.3 uses the power output suck compared to most other trucks - e.g. my 99 Blazer burned almost the same but much more powerful - and the 4.3 is such an old engine
post #13 of 22 Old Aug 30th, 2005, 01:37 PM
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Quote:
Originally Posted by b67
no way a tahoe will get near that mpg at 75-80mph. For the amount of fuel the 3.3 uses the power output suck compared to most other trucks - e.g. my 99 Blazer burned almost the same but much more powerful - and the 4.3 is such an old engine

i beg to differ, i drove the tahoe for three weeks while my path was getting repaired after i customized the passengers side on a guardrail. the Tahoe got between 22-24 same 100 mile commute same driving habits and i tracked the milege.

my path couldnt get 22 mpg if it was coasting downhill in neutral with a tail wind, other than the milage i love love love my truck for the money and reliability. the tahoe isnt nearly as reliable..... and the northstar v8 is amazing nissan should put a jap version of that motor in a pathfinder. the northstar is in my gf's deville and that gets better milege too....

Poor planning on your part does not constitute an emergency on my part........

Last edited by architectdave; Aug 30th, 2005 at 01:41 PM.
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post #14 of 22 Old Aug 30th, 2005, 01:52 PM
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Quote:
Originally Posted by architectdave
Animal Im not sure if your asking me or if your question is rhetorical. ...
I'm still adjusting to computer driven FI systems too, so my questions are "possible considerations."
My understanding (which may not be 100% correct) is that there are optimal settings and conditions engines are designed to run at. The ECU will make adjustments to these mainly for emissions, not for performance. And, if I am not mistaken, older systems continually attempt to return to the specified settings and make adjustments dynamically as the vehicle is running. I'd enjoy looking over the program diagram for these ECUs (if one exists).
19 MPG isn't bad for a 3.3l pushing that much weight, particularly if you don't drive like a granny (no offensive meant toward any senior citizen) which I doubt you do. I would be a bit concerned with a constant or consistent knock. This can lead to damage to the engine. If you suspect carbon is building up, you could try using one of the products that cleans out the carbon. A friend of mine is a marine mechanic and recommends Carbon Blaster. They use it in all kinds of engines, most are automobile engines with marine parts attached. There are also fuel stabilizers that, in addition to other benefits such as cleaning, reduce knocking.

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post #15 of 22 Old Aug 30th, 2005, 02:02 PM Thread Starter
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So, replaced the knock sensor the first time which included removing the entire intake manifold and getting replacement gaskets and such. The harness for the knock sensor needed to be replaced as well as seems someone jerryrigged or muffed it up as one time or another.

Got it all back together fired up and everything seemed good.

Next day, CEL again. Misfire in cylinder 2. Thought maybe it was in dire need of a tune up and haven't done it since I bought the thing a couple of months ago so did the cap, rotor, plugs and wires. Ran a little better but still had the misfire. Tested pulse to injectors and everything was good. So ended up pulling the intake back off, getting new gaskets, flushing all the injectors. Turns out cylinder 2 injector was fubared so that go replaced.

Now it runs like new which is nice.

And no I didn't do all this work myself except for the basic tune up.

Just bought this thing for 6000, starter went 2 days later and it needed new tires, now all this and I've got more money into it then I wanted but now it's cool I guess.

sorry for the long post.
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