filled up with 89 octane for the first time a couple weeks ago. have always used 93 before. today my CEL came on. pulled 3 codes: P0325 (two instances) and P0135. guess my KS and 02 are kaput. anyone know which 02 sensor that is??

 

I doubt that the 89 octane gas had anything to do with the codes. Chalk it up to a coincidence.

 

Yeah filling up your tank with lower octane wont just fry things in your car. Its just a coincidence.

 

It was NOT the 89

http://forums.maxima.org/showthread.php?t=460099
http://forums.maxima.org/showthread.php?t=472450
http://forums.maxima.org/showthread.php?t=474038

 

maybe not fry the O2, but a sudden onset of abnormal pinging from using low octane gas might stress an otherwise dormant KS to the breaking point. seems a little too coincidental to me.

 

More than likely they were already starting to go. And 89 isnt even that low.. I have always used 93 octane too but I highly doubt that if I filled up with 89 octane that my 02 sensor would just die.

 

You haven't a clue on how these systems work.

Change the o2 sensor.

 

why the insult? and you should be careful who you call clueless. I'm an MSEE and design electronics for a living and have tested piezoelectronic transducers in the lab and have seen them fail from a sudden increase in amplitude at their resonant frequency. since you are an expert, I shouldn't have to explain why this is relevant to my theory on bad gas causing a KS failure. of course it is just a theory.

What I do not know is how/why the KS code relates to the O2 code, or why simply replacing the O2 sensor will fix any "ghost" KS condition. on that point you are correct, I do not have a clue. but the threads you referenced didn't answer these questions either. most of the posts were riddled with confusion.

 

Well, the KS code doesnt set off the CEL light anyways. Im thinkin that maybe the sudden octane change to an already weak or lazy O2 sensor set off the light; and you just happened to notice the code for the KS, waiting there to be discovered, while you were investigating the CEL, which was really on for the O2.

 

that could be. I thought I read that a KS does sometimes throw a CEL? I did check for codes a few months ago when I bought my OBDII reader and there were none, but I suppose the KS code could've showed up soon after.

 

your computer is programmed to run 87 octane. 89 diddnt do that.

 

The KS usually always comes as a ghost code with O2 codes.
Chances are the KS is fine, as NexMAX suggested, change the O2.

 

I have been putting 87 in my beater max for almost two years now... nothing fried, melted, exploded, imploded, spontaneously combusted, spontaneously froze, vaporized, condensed or otherwise had an unexpected change of state, volume, shape or size. I'm guessing it's not the 89 that did it.

 

my CEL came on about 3 months back and i pulled those codes too, just clear the ECU and see if the CEL comes back on.

 

uhhh... I don't think its possible to burn out ur KS with gasoline, unless u poured it directly on it and lit it on fire urself...

 

To answer your question, the PO135 code is oxygen sensor upstream heater fault (right bank).. Which i believe is the sensor closes to the radiator, had the same problem with that one at 150k..

 

umm yea....is not the 89..........an ur knock sensor is never dormant...the ecu will advance timing until it detects knock thru the knock sensor then back it off....ur knock sensor is constantly active....just becuase u work in the electronics world does not mean u know the functionality of a NISSAN KNOCK SENSOR....cause i know a few mechanical engieers that have no clue how to fix a car...

 

I never meant it as an insult.

I get perturbed when people on here think that the KS will be annihilated due to being 'worked' too hard when using lower or higher octane fuel. That's an annoying pet peeve of mine. I use 87 on my A32 and it's still fine....No imploding.

When the KS is out of spec, the ECU interprets the information and retards timing, so the car runs poorly and has unimpressive MPG.

It's good to know you've done that type of thing in your lab and have furthered your education. The KS/o2 code is notorious for being a false KS code.

Reading the FSM and getting familiar with Nissans A32 electronics is probably a good place to start. Since you already have the formal educational background, you should be that much ahead of the normal non-electronics person.

 

i would like to add that i was also not insulting u....NmexMax is right...people all the time post about how they needed to go qith 87 and it fried their KS...when it simply isnt true...

 

From page EC-24 in the FSM...

at the very least, the ABNORMAL use of 89 (when only 93 has been used in the past) could expose an already defective (and dormant) KS that would otherwise register normal voltage readings - it does not have to be shorted or open to be defective - such is the nature of piezoelectronic devices.

this might explain all the people who post that a random fill of 87 fried their KS. although I still suspect high amplitude transients can break these things.

and if you run 87 all the time, you would've known long ago if your KS was good or bad, so this scenario wouldn't apply to you.

Also, I have since cleared the codes. the KS code is back, but not the O2 code, so in my case they are not related.

 

I use 87-91 and occasionally 100.... Never fried itself.

 

FYI. I showed three codes recently. 1 KS, 2 for the same O2 sensor. While conventional wisdom suggest replacing the O2 sensors first, then seeing if the KS code returns, I found success with the opposite.

That is, because it was clearer to me which KS needed to be replaced (there is only one KS, and 4 02 sensors on my California spec 99 Max), I went ahead and replaced the KS first and reset the codes. Voila, none of the codes have reappeared and I am leaving my O2s alone for the time being.

 

but in ur orignal post u make it sound like it does nothing until it hears a ping or knock....but there is a constant power supply to it so it is always ON....its just a microphone anyway.....but whatevr ur an electrical engineer so what do i know.....

 

there's enough pissing and moaning going on, i dont want to chime in.

if it makes you feel better, change your ks, change all your o2 sensors and ONLY use 93 from know on, in fact, if you go to sunoko, they offer 94, use that. i mean, thats what nissan would tell you after they bent you over for all them..............
after all they built the car, they should know :BS:

 

but that is the point - in fact it does nothing until it senses vibration that falls within its bandwidth (it is tuned to pick up on engine pinging). even though it is drawing a small DC current in steady state (~4uA, which is called biasing current), it just sits there and does nothing until it is called into duty (kind of like a stereo amp when there is no input signal). When it does hear a ping the piezo device generates a voltage waveform (now it is "active"), and there is likely a diode or transistor inside that rectifies it and uses it to change the pin voltage at the ECM. That change is what triggers action, not the constant draw of biasing current.

But it is not called into duty by the ECM constantly trying to advance the timing as far as possible and then backing off - that is a common misconception on this board. it is a fail safe measure that springs into action only when it needs to. such as when low octane gas is used.

Since these things can fail in a number of ways (open, short, or just out of spec voltage if/when they hear a knock) there is no gurantee the ECM will even know there's a problem until the thing does something screwy in response to engine pinging. If it has been sitting for years unused, and you never use low octane gas, you may never know if it is good or bad (unless it is shorted or open).

my assumption is that if the ECM detects a KS failure it reverts to some "safe mode" where it can safely run on 87 octane, and you would have to reset the ECU to get your power back. I didn't see mention of this in the FSM, though.

unfortunately, the FSM does not provide detailed technical scematics of the internal KS circuitry or the ECM sensing circuitry or I could give you an even more indepth analysis of this thing.

 

I would say :random coincidence. Let me throw something on the table. Lots of talk about octane, knock sensor etc. My 98 uses 92 octane and pings at 3400 rpm, peak power band. No codes, cel or anything. I get fantastic MPG and good performance. Should I randomly start replacing o2 sensors, knock sensor, coil packs and injectors or do I wait until my cel comes on and I break down in the middle of BFE? If you have encountered this, please speak up.

 

i hear what understand what ur saying.......but i interpret that as if the knock sensor fails or detects a constant pig or knock it will go into "safe" mode
and have timing retardrd constantly.....ur irght the FSM doesnt give a ton of info on the system itself....but again u may understand better than me or whatecver my my compreshension of the the whole knock sensor maybe be differnt than urs...like i said....i think the ECm will advance timing to a certain point lets say 17 degrees for instance....the ECU will keep it there until it dtect a ping that back it off to 16 or 15....so its constantly hearing thinks and adjusting timing accordingly.......thats the way i look at it.....u can run 87 all u want but the ecu will retard accordingly...and once u go back to 93 it will advance accoridingly....but when the KS fails completely there is a safe mode and thats where we all get the power loss from....ur right its hard to really know how it actually works...but lets be real there are if a KS fried cause u switched octane people would br replacing KS all the time....i have switched from 94 to 93 to 87 to 91 to 110 and never has a KS issue in either of my 4th gens.....but it all check O2s first they give KS ghost code

 

What year is your Maxima, sky jumper, and how many miles are on it?

I take it that a knock sensor is good for about 100K? Are you approaching that mileage?

Once again, I call bs on the 89 octane gas having anything to do with your problems. There are numerous .orgers who reduced octane to save money as a result of high gasoline prices during the past year or so and this is the first post I have read blaming lower octane on anything other than, perhaps, less power at the butt dyno.

 

in all my searching, I haven't seem to come to a clear answer... I went to AutoZone a few weeks ago and came up with a p0133 & p0153 codes, and as of now the car has been knocking.. with all of this reading, in anyone's best opinion, would you think my issue is a KS or O2 or both....

as of this moment I'm not sure if I have a Cal or Non-Cal car, but I'm in PA, so I'm only guessing at Non-California... so if it is most likely the O2, is it worth changing all three sensors at one time just in case? or should I do the two O2 sensors the AutoZone reports and swap in a new KS too?

 

If you just get P0133 and P0153, why would you even think about a KS? Unless it threw P0325, I wouldn't worry about it.

 

Sky Jumper; I have thought about what you stated and re-read a few chapters of my college theory books.

No matter the the amount of time the transient response takes to occur, it should still not burn the KS, because its resistance is constant and was designed to resonate with a certain frequency band in mind. Unless its resistance has been affected by an unknown source.

The only source that can change the resistance of the KS that i can come up with is temperature, but even assuming that all conditions are perfect and you poured 89 on the hottest day of the year, that resistance would have to be changed by a lot in order for the transient wave of current to blow the KS.

In fact, The current supplied by the KS circuit would be limited to the value that it takes to blow the KS, since its resonat frequency is the same as knock frequency, nissan obviously would have calculated the maximum current the KS is able to handle and would back off in order for this would not happen.

Maybe i am looking at this the wrong way but it is after all a simple circuit. Please tell me what you think...

Oh and getting angry at Sky jumper for proposing a theory is quite ignorant.

 

well, because its been knocking/tapping... or will the o2 replacement fix that as well?

 

Old thread, but I've used 87 for over 8 years, and my KS is fine.

 

How in the hell would replacing an O2 sensor fix a knock issue?

Also, the knock sensor can't do a damn thing for a physical knock, like a rod bearing.

 

wow back from the dead this thread.

I suppose a better title for this thread would've been "temperature extremes and lack of use made my KS's piezo element weak, and then its first bout of knock in 7 years broke it". but that just seems too wordy.

andrei -- the failure mode is mechanical, not electrical -- this is to say the cause of the failure is mechanical stress on the piezo element (vibration, etc), and the effect is voltage out of spec (which the ECM picks up as a KS failure). piezo devices are fragile and break easily (hence nissan's warning not to drop the knock sensor). it is a bit ironic that the very mechanical stress the KS is designed to detect (engine knock) can very well destroy it - but the KS is tuned (e.g. the piezo element will physically vibrate) at the frequency of engine knock, so this shouldn't be too surprising given how fragile the things are.

think of it this way - if you overdrive a flimsy (fragile) loudspeaker the cone will physically tear (if the voicecoil doesn't melt first) - the failure is mechanical. or if you store a loudspeaker outside in the sun unused for 10 years the paper cone and rubber surround will turn brittle, and the instant you hook it up to an amp it will tear. I've had this happen to me.

likewise, if your dormant KS is exposed to long periods of temperature extremes the piezo element can turn "brittle" for lack of a better term, and the moment it is finally exposed to mechanical stress within its bandwidth (e.g. you one day decide to run 87 or 89) it might break. in the lab we conducted ALT (accelerated life testing) on piezoelectric RF filters for cell phones and discovered that temperature cycling between extreme hot & cold would sometimes cause these things to break sporadically - i.e. we could not predict it. now just think of the temperature extremes the KS is exposed to.

Since I originally started this thread I have done far more testing of the KS functionality than I'd like to admit, and I can tell you if you always run >91 then the thing just sits there like a bump on a log doing nothing (and hearing nothing). and you will never know if the thing is about to break unless/until you run low octane gas or otherwise induce engine knock some other way. just to reiterate -- the default 4th gen timing map is programmed NOT to cause knock so long as premium fuel is used. KS is only there as a fail safe.

 

Ok that makes complete sense, thanks, that was a great explanation.

I replaced my KS this summer and began the unthinkable for me -- started using 91 shell v power. great mpg increase (23-24 consistently mostly in the city) so i guess the extra money i spend is worth it in the long run.

 

you're a real douchebag aren't you? I asked a question because I obviously dont know the answer.... not all of us have nothing better to do than to sit on the net and read about cars all day, some of us actually have to work for a living...

that being said.... I'm all ears for POSITIVE feedback/information

 

It's common sense, an O2 sensor has nothing at all to do with knocking...nor can replacing it fix a knock.

 

its only common sense if you are familiar with all the workings of a vehicle.. I'm not a mechanic nor do I have all day to read the entire internet to answer a question I might have, and much less do I have time to read sarcastic unwarranted remarks!

 

But you have time to reply to them?