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  1. 6 points
    This is the most pointless exercise ever, and i love it. I couldn't have even dreamed of anyone trying to measure knock with a jaycar multimeter. Also love your 20/20 hindsight knowledge. Everything anyone posts you 'already knew'. Good luck figuring it out!
  2. 5 points
    For f**k's sake Slap. You cannot measure frequency with voltages. You just cannot. It is time for you to let the big boys carry on and go play with your pathetic ideas quietly by yourself. Almost all of those ideas have no place in the real world anymore, as we have no need to bandaid shitty solutions to problems that can be fixed by proper selection and adjustment of the correct equipment.
  3. 4 points
  4. 4 points
    No, it cannot. From your posts it comes across like you have a LOT to learn, I'll try and give a bit of a concise enough ramble which if I get where you are at right and you are willing to take something on board it may help you think about things a bit differently and maybe learn something. So, think of knock sensors not as something measuring knock... but measuring the vibrations being transferred through whatever it is attached to. The sensor is effectively communicating the movement of those vibrations to the best of it's ability, it isn't giving a voltage representing the rate of the movements (aka frequency), but the strength and direction of those movements. If you had a sensor which was outputting a 1KHz square wave signal with a 1volt amplitude, and another sensor which was outputting a 1KHz square wave signal with a 2volt amplitude and tried to analyse that signal with a voltmeter you would not read the same voltage from those two sensors which are signalling the exact same frequency. Bearing that in mind, this pretty much explains why there is no set voltage where you are experiencing "knock". There are a few things which can influence what the signal from a knock sensor looks like - for starters: * Is it a resonant (more sensitive to a given frequency range) or a flat response sensor? * Where is the sensor located? * What is the resonant frequency of the engine being used? * What rpm is the engine operating at? * How noisy is the engine itself? You need signal processing of some sort if you hope to intelligently identify knock. You can probably do it with analog components but given the level of naivety you are indicating I could be forgiven for assuming you aren't going to be building custom circuits with effective utilisation of band pass filters etc to suit your given setup. There is a lot more data that comes from a knock sensor than just a threshold voltage which means knock, which means you really have to work to make reliable sense of it if you want automated detection of "stuff"- but you also can use them for a lot more too. This may give a bit of an indication of the kind of thing you can expect to see from a knock sensor, and what you can use the data for. In this case I was trying to identify the cause of a misfire on an car which pulling the plugs on to check was a non-trivial job, so I used windowing (split the signal from the knock sensor based off which cylinder was in it's combustion cycle so I align the noise with the busiest cylinder) and some signal filtering to even out the noise versus engine speed. Using that it became pretty clear which cylinder stopped firing when the car hit full boost.... check out the red line in the top graph. That's basically using less noise than "normal" to identify the lack of combustion, as opposed to using excessive noise to identify uncontrolled combustion. Analog tuning, what? PS, all of this is just trying to teach something with no rational thought process to react to a specific bunch of parameters you have set. It can't be guaranteed to always detect knock, and it can't be guaranteed that when it reacts that it is really knocking. It's just responding in prescribed way to a signal which meets some rules you've provided.
  5. 3 points
    Seriously dude you should stop giving advice
  6. 2 points
    You are thinking about it wrong. NA engine cylinder inhales 1x swept volume per intake event. Ignoring volumetric efficiency of course. Put turbo onto engine, running 1 bar of boost. Let's ignore the effect of increased exhaust manifold pressure for the moment. That turbo'd cylinder still inhales 1x swept volume per inlet event, but now that gas is at double the density. Twice as much mass of air gets into the cylinder. And the ECU has to chuck in twice as much fuel to go with it. You now have twice the energy (from fuel) released during the combustion event and hence twice the power. It is THAT simple. (Except that it is not, because of the various confounding factors, such as EMP, differences in cam duration & timing, static comp ratio, charge temperature, that all add up to drop us below a simple doubling of power. But we still go up towards double the power, just because we're chucking in double the amount of fuel). All the compression ratio does on top of that is make it possible to burn the stuff the way we want it to and get the mechanical force out of onto the crank. If you have a turbo giving 1 bar of boost, and you have an intercooler that brings it down to near ambient (so we don't have to consider too much extra heat coming along for the ride) then you can compress the charge at nearly the same compression ratio as you would in an NA version of the engine, because the temperature rise associated with the compression event depends on the ratio of P2/P1, not simply the final pressure. In practice, we still need to keep the turbo'd engine's CR lower than we might on an NA version, by maybe a whole ratio point, because it's not just the temperature rise that can lead to detonation. There's a lot of blah blah involved in that, and it is EXCRUCIATINGLY well documented in millions of words on the subject already, so I'm not even going to try. But what is important is that your simple arithmetic leading you to this psi value or that psi value is not the correct way to approach it.
  7. 2 points
  8. 2 points
    Slap, the problem is what you have said doesn't make sense. How are you getting these knock voltage readings? The ecu doesn't adjust some kind of voltage to tune its own knock sensitivity. If you want some technical reading check out the nistune forum. That is where to find out how the skyline ecu works
  9. 2 points
    If you don't like what I post to you, please report my posts to the moderators.
  10. 1 point
    Yet, you said, out loud to the hearing of all in this forum, that the idle speed is adjusted with the screw on the idle valve. That was after you had been told multiple times that the ECU was in control of it. Yup, and it will remain so whilst the voltage is being measured and reported by someone in whom we have no trust in their technical capability. I can tell you right now that I would not expect to measure a DC voltage on either terminal of the knock sensor. Perhaps all your buggerising around has broken something in your ECU. That would be a logical expectation on our behalf. This is news to us. In your previous post, did you not express no knowledge of how filters work? Wat? No. As posted above by Ben, THE ECU DOES NOT POWER THE KNOCK SENSOR. As I posted earlier, the knock sensor is a microphone and GENERATES the voltages that turn up on its terminals by the piezoelectric effect. You really should read what we post and then go look up that which you do not understand. No. No. No. No. There is no way that I can tell you how far arse-backwards you have that scheme. No, a signal can be carried with almost no current at all. If you use an input circuit on your receiver (the ECU in this case) that has massive impedance (let's say some megaohms) then all that happens is that the voltage applied to the input terminals is directly measurable at that point with almost no current flowing. This is the principle of measuring voltage. In this case however, I don't know the input impedance of the ECU's knock sensor terminals, so I will make no representation of what it is. I would, however, expect it to be very high. No. You are talking the difference between passive and active microphones. All that active powered microphones have is basically a method of increasing the signal level at the microphone itself. Almost all microphones are passive and they need to be plugged into an amplifier to turn their tiny signals into sufficiently high level to drive a speaker. Conventionally that is a chain of a mic pre-amp followed by a power amp, simply because the various different sorts of microphones generate different sized signals compared to line level audio signals and need different pre-amp treatment. Despite all that.....it is immaterial here. The ECU is not trying to play the knock noises into the cabin for you to hear. It is quite capable of listening for knock noises at the microphone signal level. There may well be a small pre-amp stage in the ECU to make the signal larger, but I wouldn't expect it. THERE IS NO POWER TO THE KNOCK SENSOR. No. No. No. As posted by Ben, again, the knock sensor is not a 5V sensor that simply changes its resistance with whatever it is measuring. It is not. Therefore your continued pushing of that line that your 2.4V means something shows that you have not understood what you have been told over and over again. Have a looooooooong look at the graphic posted by RICE again. Note the midpoint of the waveform is at ZERO volts. Zero. There should be no DC bias on the knock sensor. What have you done to your car? No. You are just bashing out meaningless terms now. No. They are not in code. They will be in hardware. No, I did not contradict myself. The ECU DOES NOT ADD TIMING TO THE BASE 15° to get you the mythical 30° that you claim your engine idles at. That is the point I have made, more than once, about your incorrect claim. The other things I have said about the ECU using timing to attempt to control idle speed AS A MATTER OF LAST RESORT are all true. I will not reiterate all that typing. You are doing my head in as it is. No. No. No. Take an early one, like an RB20. The wax pellet valve is a separate device, lodged under the inlet manifold. It is the AUXILIARY AIR VALVE and it is responsible for opening up a big air leak to give a cold start high idle. The idle control valve is on the back end of the plenum and is controlled by the ECU. Take a later one, like a NEO. The wax pellet valve is integrated into the IACV and does the same job as it does on the RB20. Open when cold, closed when warm. This is why the NEO has a coolant feed to the IACV on the back end of the plenum. It feeds cold or warm (or hot) water to the wax pellet to allow it to sense the engine temperature directly. The stepper motor controlled valve is still under the control of the ECU for normal idle control. I am pretty sure that Nissan will have abandoned such old fashioned shit by now and not be using wax pellet valves at all. They will do everything with the IACV, like every other manufacturer does. We can't comment on what you may have done to your car. That's because you have butchered the system. I believe the word you are looking for in all your usages so far is "respectfully". Not respectively, which has a completely different meaning. /thread, please mods.
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