b16 knock sensor infinite resistance
b16 engine, knock sensor seems to have infinite resistance. this
normal? (just bought the knock sensor used on ebay; i know about ebay sellers, but there is no reason to think the seller is screwing me, he has long good history, and i haven't seen a lot of complaints anywhere about a high proportion of knock sensors going bad) if it is infinite resistance, how does the ecu (obd1) know whether you have one hooked up, but you're not knocking? cause it gives you an error code if you don't have it. being solid state, i'm dubious that it's a superhigh impedance that my meter can't detect, but maybe, FETs and all.... (for those with burning curiosity [tegger you listening?], presumably it's in limphome mode when it gives me the no knock sensor error code: but vtec still switches over, runs great at middle rpms, stumbles a lot from idle if you floor it from idle, but if you stick with part throttle until the revs are up a bit it does perfectly fine; might or might not stumble once or twice when floored at highish rpm (below vtec level), not sure but that seems to be dependent on temp more than anything, maybe it plays it safe at full throttle if it sees the engine is warm but doesn't have to if it sees it's cold? or maybe it's thinking about something else entirely and the temp is a coincidence. at any rate, limphome mode is certainly more drivable and more complicated than it's been described to me as being. certainly, everybody always says limphome has no vtec, but you can't mistake it with a b16, it's operative exactly when you expect it. maybe there are more than one limphome modes, depending on the particular failure? and please don't tell me my engine is going to knock itself to pieces, i'm running on premium and i'm pretty sure the thing isn't set up to default to aviation gas type tuning without the knock sensor to constantly detune it to run on mere premium. oh, and it's bone stock, no blower or anything of course) |
Re: b16 knock sensor infinite resistance
z wrote:
> b16 engine, knock sensor seems to have infinite resistance. this > normal? (just bought the knock sensor used on ebay; i know about ebay > sellers, but there is no reason to think the seller is screwing me, he > has long good history, and i haven't seen a lot of complaints anywhere > about a high proportion of knock sensors going bad) > > if it is infinite resistance, how does the ecu (obd1) know whether > you have one hooked up, but you're not knocking? cause it gives you an > error code if you don't have it. being solid state, i'm dubious that > it's a superhigh impedance that my meter can't detect, but maybe, FETs > and all.... FWIW the knock sensor on my Subaru Impreza is supposed to be between 400k and 700k Ohms. What resistance range does your service manual say is OK for the knock sensor? If it's outside that range it needs to be replaced. I can imagine that some knock sensors might be capacitively coupled and would appear to be an open circuit measured with a DC ohmmeter. It all comes down to what the troubleshooting chart in your manual says. If you don't have a manual and you're trying to troubleshoot by replacing parts, buying a used part isn't a good strategy (of course diagnosing by part replacement is more costly and less effective than the correct method). |
Re: b16 knock sensor infinite resistance
Mark Olson <olsonm@tiny.invalid> wrote:
>z wrote: >> b16 engine, knock sensor seems to have infinite resistance. this >> normal? (just bought the knock sensor used on ebay; i know about ebay >> sellers, but there is no reason to think the seller is screwing me, he >> has long good history, and i haven't seen a lot of complaints anywhere >> about a high proportion of knock sensors going bad) >> >> if it is infinite resistance, how does the ecu (obd1) know whether >> you have one hooked up, but you're not knocking? cause it gives you an >> error code if you don't have it. being solid state, i'm dubious that >> it's a superhigh impedance that my meter can't detect, but maybe, FETs >> and all.... > >FWIW the knock sensor on my Subaru Impreza is supposed to be between 400k >and 700k Ohms. What resistance range does your service manual say is OK >for the knock sensor? If it's outside that range it needs to be replaced. > >I can imagine that some knock sensors might be capacitively coupled and >would appear to be an open circuit measured with a DC ohmmeter. It all >comes down to what the troubleshooting chart in your manual says. If you >don't have a manual and you're trying to troubleshoot by replacing parts, >buying a used part isn't a good strategy (of course diagnosing by part >replacement is more costly and less effective than the correct method). I believe that they are just a piezo element. Shake them at the right frequency, and a very high voltage (but hardly any current) comes out. There's no actual electronic stuff in the sensor aside from the element. You could probably connect one to a high-Z microphone input and tap on it to see if it was working. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
Re: b16 knock sensor infinite resistance
kludge@panix.com (Scott Dorsey) wrote in
news:g8fagj$cgv$1@panix2.panix.com: > Mark Olson <olsonm@tiny.invalid> wrote: >>z wrote: >>> b16 engine, knock sensor seems to have infinite resistance. this >>> normal? (just bought the knock sensor used on ebay; i know about >>> ebay sellers, but there is no reason to think the seller is screwing >>> me, he has long good history, and i haven't seen a lot of complaints >>> anywhere about a high proportion of knock sensors going bad) >>> >>> if it is infinite resistance, how does the ecu (obd1) know whether >>> you have one hooked up, but you're not knocking? cause it gives you >>> an error code if you don't have it. being solid state, i'm dubious >>> that it's a superhigh impedance that my meter can't detect, but >>> maybe, FETs and all.... >> >>FWIW the knock sensor on my Subaru Impreza is supposed to be between >>400k and 700k Ohms. What resistance range does your service manual >>say is OK for the knock sensor? If it's outside that range it needs >>to be replaced. >> >>I can imagine that some knock sensors might be capacitively coupled >>and would appear to be an open circuit measured with a DC ohmmeter. >>It all comes down to what the troubleshooting chart in your manual >>says. If you don't have a manual and you're trying to troubleshoot by >>replacing parts, buying a used part isn't a good strategy (of course >>diagnosing by part replacement is more costly and less effective than >>the correct method). > > I believe that they are just a piezo element. Shake them at the right > frequency, and a very high voltage (but hardly any current) comes out. > There's no actual electronic stuff in the sensor aside from the > element. > > You could probably connect one to a high-Z microphone input and tap on > it to see if it was working. > --scott my Haynes manual says that the knock sensor must be checked with an AC voltmeter on the most sensitive range. Neg probe to the sensor body and pos probe to the sensor terminal. tap on the sensor with a hammer or similar device and observe voltage fluctuations on the meter. a piezo sensor would be capacitive. -- Jim Yanik jyanik at kua.net |
Re: b16 knock sensor infinite resistance
Scott Dorsey wrote:
> I believe that they are just a piezo element. Shake them at the right > frequency, and a very high voltage (but hardly any current) comes out. > There's no actual electronic stuff in the sensor aside from the element. > > You could probably connect one to a high-Z microphone input and tap on it > to see if it was working. Sure, I tested mine by measuring the resistance, then by putting my voltmeter on the sensor (on AC millivolts) and tapping with a screwdriver near the sensor and sure enough there was a signal coming out. Even though it was putting out a signal and the resistance checked out I replaced it with a new one, figuring the fault might be an intermittent open that only happens when it's hot. So far a couple of weeks and a couple thousand miles later no codes have popped up. |
Re: b16 knock sensor infinite resistance
Mark Olson wrote:
> Scott Dorsey wrote: > >> I believe that they are just a piezo element. Shake them at the right >> frequency, and a very high voltage (but hardly any current) comes out. >> There's no actual electronic stuff in the sensor aside from the element. >> >> You could probably connect one to a high-Z microphone input and tap on it >> to see if it was working. > > Sure, I tested mine by measuring the resistance, then by putting > my voltmeter on the sensor (on AC millivolts) and tapping with a > screwdriver near the sensor and sure enough there was a signal > coming out. Even though it was putting out a signal and the > resistance checked out I replaced it with a new one, figuring the > fault might be an intermittent open that only happens when it's hot. > So far a couple of weeks and a couple thousand miles later no codes > have popped up. Hi, It is Piezo transducer precision tuned to specific freuency. Just replace it with new one if it gives trouble. |
Re: b16 knock sensor infinite resistance
Tony Hwang wrote:
> Mark Olson wrote: >> Scott Dorsey wrote: >> >>> I believe that they are just a piezo element. Shake them at the right >>> frequency, and a very high voltage (but hardly any current) comes out. >>> There's no actual electronic stuff in the sensor aside from the element. >>> >>> You could probably connect one to a high-Z microphone input and tap >>> on it >>> to see if it was working. >> >> Sure, I tested mine by measuring the resistance, then by putting >> my voltmeter on the sensor (on AC millivolts) and tapping with a >> screwdriver near the sensor and sure enough there was a signal >> coming out. Even though it was putting out a signal and the >> resistance checked out I replaced it with a new one, figuring the >> fault might be an intermittent open that only happens when it's hot. >> So far a couple of weeks and a couple thousand miles later no codes >> have popped up. > Hi, > It is Piezo transducer precision tuned to specific freuency. Just > replace it with new one if it gives trouble. indeed. |
Re: b16 knock sensor infinite resistance
On 8/19/08 2:25 PM, in article
4f2daefa-8013-4db5-a9a7-ec87150c4cf1...oglegroups.com, "z" <gzuckier@snail-mail.net> wrote: > b16 engine, knock sensor seems to have infinite resistance. this > normal? (just bought the knock sensor used on ebay; i know about ebay > sellers, but there is no reason to think the seller is screwing me, he > has long good history, and i haven't seen a lot of complaints anywhere > about a high proportion of knock sensors going bad) > > if it is infinite resistance, how does the ecu (obd1) know whether > you have one hooked up, but you're not knocking? cause it gives you an > error code if you don't have it. being solid state, i'm dubious that > it's a superhigh impedance that my meter can't detect, but maybe, FETs > and all.... > > (for those with burning curiosity [tegger you listening?], presumably > it's in limphome mode when it gives me the no knock sensor error code: > but vtec still switches over, runs great at middle rpms, stumbles a > lot from idle if you floor it from idle, but if you stick with part > throttle until the revs are up a bit it does perfectly fine; might or > might not stumble once or twice when floored at highish rpm (below > vtec level), not sure but that seems to be dependent on temp more than > anything, maybe it plays it safe at full throttle if it sees the > engine is warm but doesn't have to if it sees it's cold? or maybe it's > thinking about something else entirely and the temp is a coincidence. > at any rate, limphome mode is certainly more drivable and more > complicated than it's been described to me as being. certainly, > everybody always says limphome has no vtec, but you can't mistake it > with a b16, it's operative exactly when you expect it. maybe there are > more than one limphome modes, depending on the particular failure? and > please don't tell me my engine is going to knock itself to pieces, i'm > running on premium and i'm pretty sure the thing isn't set up to > default to aviation gas type tuning without the knock sensor to > constantly detune it to run on mere premium. oh, and it's bone stock, > no blower or anything of course) Admittedly my knock sensor experience is with Nissans rather than Hondas, but it really sounds to me like you're barking at the wrong tree. I've not heard of a knock sensor that can put a car into limp home mode. In a Nissan, it doesn't even light the check engine light when it malfunctions. Usually a knock sensor code comes up in conjunction with other codes when it "hears" other things related to the real problem clanking around in there. Your description sounds more like a transmission problem. |
Re: b16 knock sensor infinite resistance
E Meyer <epmeyer50@msn.com> wrote in
news:C4D19785.33397%epmeyer50@msn.com: > On 8/19/08 2:25 PM, in article > 4f2daefa-8013-4db5-a9a7-ec87150c4cf1...oglegroups.com, "z" ><gzuckier@snail-mail.net> wrote: > >> b16 engine, knock sensor seems to have infinite resistance. this >> normal? (just bought the knock sensor used on ebay; i know about >> ebay sellers, but there is no reason to think the seller is screwing >> me, he has long good history, and i haven't seen a lot of complaints >> anywhere about a high proportion of knock sensors going bad) >> >> if it is infinite resistance, how does the ecu (obd1) know whether >> you have one hooked up, but you're not knocking? cause it gives you >> an error code if you don't have it. being solid state, i'm dubious >> that it's a superhigh impedance that my meter can't detect, but >> maybe, FETs and all.... >> >> (for those with burning curiosity [tegger you listening?], presumably >> it's in limphome mode when it gives me the no knock sensor error >> code: but vtec still switches over, runs great at middle rpms, >> stumbles a lot from idle if you floor it from idle, but if you stick >> with part throttle until the revs are up a bit it does perfectly >> fine; might or might not stumble once or twice when floored at >> highish rpm (below vtec level), not sure but that seems to be >> dependent on temp more than anything, maybe it plays it safe at full >> throttle if it sees the engine is warm but doesn't have to if it sees >> it's cold? or maybe it's thinking about something else entirely and >> the temp is a coincidence. at any rate, limphome mode is certainly >> more drivable and more complicated than it's been described to me as >> being. certainly, everybody always says limphome has no vtec, but you >> can't mistake it with a b16, it's operative exactly when you expect >> it. maybe there are more than one limphome modes, depending on the >> particular failure? and please don't tell me my engine is going to >> knock itself to pieces, i'm running on premium and i'm pretty sure >> the thing isn't set up to default to aviation gas type tuning without >> the knock sensor to constantly detune it to run on mere premium. oh, >> and it's bone stock, no blower or anything of course) > > Admittedly my knock sensor experience is with Nissans rather than > Hondas, but it really sounds to me like you're barking at the wrong > tree. I've not heard of a knock sensor that can put a car into limp > home mode. In a Nissan, it doesn't even light the check engine light > when it malfunctions. > > Usually a knock sensor code comes up in conjunction with other codes > when it "hears" other things related to the real problem clanking > around in there. Your description sounds more like a transmission > problem. > > a knock sensor just changes(retards) the ignition timing to stop knock. http://wiki.answers.com/Q/What_does_a_knock_sensor_do -- Jim Yanik jyanik at kua.net |
Re: b16 knock sensor infinite resistance
Jim Yanik wrote:
> E Meyer <epmeyer50@msn.com> wrote in > news:C4D19785.33397%epmeyer50@msn.com: > >> On 8/19/08 2:25 PM, in article >> 4f2daefa-8013-4db5-a9a7-ec87150c4cf1...oglegroups.com, "z" >> <gzuckier@snail-mail.net> wrote: >> >>> b16 engine, knock sensor seems to have infinite resistance. this >>> normal? (just bought the knock sensor used on ebay; i know about >>> ebay sellers, but there is no reason to think the seller is screwing >>> me, he has long good history, and i haven't seen a lot of complaints >>> anywhere about a high proportion of knock sensors going bad) >>> >>> if it is infinite resistance, how does the ecu (obd1) know whether >>> you have one hooked up, but you're not knocking? cause it gives you >>> an error code if you don't have it. being solid state, i'm dubious >>> that it's a superhigh impedance that my meter can't detect, but >>> maybe, FETs and all.... >>> >>> (for those with burning curiosity [tegger you listening?], presumably >>> it's in limphome mode when it gives me the no knock sensor error >>> code: but vtec still switches over, runs great at middle rpms, >>> stumbles a lot from idle if you floor it from idle, but if you stick >>> with part throttle until the revs are up a bit it does perfectly >>> fine; might or might not stumble once or twice when floored at >>> highish rpm (below vtec level), not sure but that seems to be >>> dependent on temp more than anything, maybe it plays it safe at full >>> throttle if it sees the engine is warm but doesn't have to if it sees >>> it's cold? or maybe it's thinking about something else entirely and >>> the temp is a coincidence. at any rate, limphome mode is certainly >>> more drivable and more complicated than it's been described to me as >>> being. certainly, everybody always says limphome has no vtec, but you >>> can't mistake it with a b16, it's operative exactly when you expect >>> it. maybe there are more than one limphome modes, depending on the >>> particular failure? and please don't tell me my engine is going to >>> knock itself to pieces, i'm running on premium and i'm pretty sure >>> the thing isn't set up to default to aviation gas type tuning without >>> the knock sensor to constantly detune it to run on mere premium. oh, >>> and it's bone stock, no blower or anything of course) >> Admittedly my knock sensor experience is with Nissans rather than >> Hondas, but it really sounds to me like you're barking at the wrong >> tree. I've not heard of a knock sensor that can put a car into limp >> home mode. In a Nissan, it doesn't even light the check engine light >> when it malfunctions. >> >> Usually a knock sensor code comes up in conjunction with other codes >> when it "hears" other things related to the real problem clanking >> around in there. Your description sounds more like a transmission >> problem. >> >> > > a knock sensor just changes(retards) the ignition timing to stop knock. > http://wiki.answers.com/Q/What_does_a_knock_sensor_do > to be pedantic, the sensor doesn't do that - it provides info to the computer which can then be used in ignition timing calculations. with no sensor input, the ignition is at a default [comparatively retarded] setting, but with sensor input, ignition can be advanced to optimum. |
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