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knock sensor thing is pissing me off

Discussion in 'ECU's, Electronics, and Tuning' started by tab, Jul 2, 2004.

  1. tab

    tab Super Moderator

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    Just like the title says. My swap has been a 100% success story, make that 99% success story. <_<

    My knock sensor has plagued me from the beginning. I've double checked the wiring, and soldered every connection. I still had an intermittent KS code. So tonight, I pulled the sensor, grounded it to the block(very securely at both ends), and plugged the sensor back in. I then carefully suspended the sensor with wire ties, as I was prompted to do by others.

    I didn't go 5 miles and the CEL popped on. :( I don't even need to check what it is.

    I'm pissed. :angry: What's my next step? Do I need to use a special shielded wire, or buy a new sensor?

    Pissedoffsol, you said pull the fucker. How much is Hondata, and a P28?

    As always, feel free to comment. :roll:
     
  2. randerson165

    randerson165 Senior Member

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    I'm having the same code come up, but it is related to my timing being off.
     
  3. tab

    tab Super Moderator

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    My timing is ok. :(
     
  4. ohmstable

    ohmstable Senior Member

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    If you're talking about a H22 then I feel your pain. I had done a H22 swap into a 93 hatch and the knock sensor gave me pure problems with the P13. I tried everything, replaced it, rewired it, new ecu, shielded the wire, oscilloscoped the output to see it was okay.. nothing fixed the knock sensor code. So I just got a P28 and chipped it to run the H22 fuel/ign maps and it runs great. You don't even need to wire up the knock or IAB or anything.. If I was you I'd go with the P28.
     
  5. pills_PMD

    pills_PMD Super Moderator

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    are you using a shielded wire at all? that may be the problem
     
  6. radnulb

    radnulb Senior Member

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    run wire from knock pin to ground. Done.
     
  7. tab

    tab Super Moderator

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    So, I run a wire from the pin on the ECU for the knock sensor to ground, that's it?

    That would be fucking sweet. :)
     
  8. tab

    tab Super Moderator

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    What kind of shielding would you suggest?
     
  9. dohcvtec_accord

    dohcvtec_accord WRX Sellout

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    Maybe a silly question, but are you sure you're running it to the correct location on the D-plug?
     
  10. tab

    tab Super Moderator

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    I've triple checked it. I completely re-ran the wire and replaced the pin once, at which point I soldered each connection along the line, and used a real ECU pin. The situation improved at that point, but the problem still existed. A code about every two weeks.

    Without changing any wiring, but removing the sensor from the block, caused me to toss a code crossing town(~<2 miles). I used a good connector and a nut to pinch it on the KS itself for a ground wire. On the other side, I used the same style connector, and grounded to the block. Very sound connections and clean grounding points. I think my wiring is correct, but if I need to use a higher quality shielding wire, I will. It can't cost that much. But since I've never seen a stock wire for my car's KS, I don't know what to buy, or if it's even the problem.

    All I know is that CEL sucks balls. It causes a huge retard on the timing, which can be felt throughout the powerband. It's like dropping 20 horses with a snap of the fingers. No other code does that. At any rate, I don't have any other codes at all.

    I might try Radnulb's tip, if he confirms that's all I need to do.
     
  11. tab

    tab Super Moderator

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    I tried grounding the knock sensor pin. It didn't help at all. I throw a code as soon as my car reaches full temperature.
     
  12. ohmstable

    ohmstable Senior Member

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    hehe.. I had tried that too.. didn't do jack sheeet for me either. You have been cursed by the knock sensor gods.

    BTW if you really wanted you could run the H22 with a unchipped P28 and it'll run the engine.. not well but it'll run, probably better than the P13 with knock CEL
     
  13. tab

    tab Super Moderator

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    I'll wire it back up, and remount it to the block, that get's me a nice jog before throwing a CEL. In the mean time, I'll look for a P28 to remap like we discussed. I'm still open to suggestions if anyone else has a bright idea.

    What kind of shielded wire does everyone else run?
     
  14. xj0hnx

    xj0hnx I wanna be sedated VIP

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    Problem solved, fuck trying to make it work, get a chipped P28, then take a hammer to your KS.
     
  15. buzz1167

    buzz1167 Member

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    I haven't been with ya from the beginning so I don't know what you're running, would you mind givin me a clue in? Ecu and the exact code?

    Buzz1167
    Jon N
     
  16. tab

    tab Super Moderator

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    JDM P13 automatic ECU

    code 23, knock sensor
     
  17. buzz1167

    buzz1167 Member

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    Have you tried just wiring up 2 volts to the lead? I'm not for sure, but I think the knock sensor want's something between 1.4 and 3.5v, if you ground it its gonna freak (whitch it did I hear), of course 12v won't do either. If you have a switched 12v power supply you could always get a few 5-10k resistors from radio shack and make a simple voltage divider. I bet that would work better than any other ghetto rig.
    If you want to try it, there's no reason it shouldn't work; Unless the ECU has some complicated programming determined to screw you over becuase the voltage doesn't change. But if thats how it is, then what, your out 1$? Probably cheaper than most other idea's. Anyway if you wanna try it, and you have an 'open' 12v switched these are the ratios you need.

    12volts---20k resistor---(1.56Volts here)---3k resistor---ground

    If you cant find a 20k or a 3k resistor at radio shack, make sure the ratio is the same, you can go bigger on the 3k, up to about 4k or so, but I definatly wouldn't go lower and not much higher than 4k. Any knowlageable person at radio shack with a calculator could give you tons of combinations to do this with, but I woulnd't count on them being very smart...

    The forumla for the voltage in the middle is...
    Voltage given * Resistor2 / (Resistor1+Resistor2)

    So you have
    12 * 3 / (23)
    or 1.565 volts. You can use any resistors that give you an acceptable value, but I suggest you keep it close to 1.6v and make sure they aren't small resistors (keep them in Kilo-Ohms) otherwise it will burn out the small resistors becuase too much current will flow. With the 20k and 3k your going to be flowing about 500uA, thats *really* small and you wouldn't even have to worry about it being switched if you didn't want to.

    All you have to do after you hook this up is to connect that knock sensor wire to the part I said was 1.56volts, right inbetween the two resistors. I'd get a multimeter and check it real quick though. If it's not an open circuit then the ratios wont be right, but if you buy a pack of each resistor type (3 or 4 resistors), you can definatly make it right somehow.

    Lol if you don't want to 'splurge' on the resistors I could spend the 34c to send you an envelope full, their like 1$ for 100 online.

    Edit: I'm not Exactly sure on the voltage, if you want it wouldn't be that hard to put the knock sensor back to stock (y'know the 1 Cel every once and a while state?) and stick a voltmeter on it while you drive, it should give you enough info to let you figure out what it should be before the ECU throws a code.

    HTH
    Buzz1167
    Jon N
     
  18. ohmstable

    ohmstable Senior Member

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    I doubt that'll work. The knock sensor is looking for a complex sinewave which changes in amplitude and frequency dependent on engine vibrations. Obviously it analyses this incoming signal trying to identify a knock condition in the engine then retard the timing enough to see this knock condition dissapear in the incoming signal. I don't think you can fool it with a 1.5v DC signal or anything like that.

    But hey, I've been wrong once before :)
     
  19. buzz1167

    buzz1167 Member

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    2v's not gonna work, but grouding it...
    I hate peizo electric devices... Piezoshit, oh well, anyone got a dc to ac converter that they can build for <10$? :D I don't know how smart honda made their ecu, maybe it'll work, maybe it won't. But you've already tried all the other solutions, before you go swapping ecu's, might as well try. Anyway, resistors have interferance like nobody's buisness, thats why they can't use simple resistor circuits in radio amp's, they gotta go crazy with moffset's all over the place. It might have enough of a dirty signal to fake it out, hooking it right to the alternator would help too...

    HTH
    Buzz1167
    Jon N
     
  20. tab

    tab Super Moderator

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    I went to my local junk yard, the closest one anyway.

    I lucked out!!!! There were two 92-95 civics in the yard. One 93 Hatchie, a stick. One 93 four door EX, automatic. I was bummed when I saw the ECU was gone. But to make sure, I asked my buddy at the counter if he "shelfed" the ECU. He pointed me to the back, where I found my new P28 Automatic ECU.

    Let the fun begin. :)

    Oh yeah, here's the kicker. I was only checking there since the ECU's on Ebay were going pretty high. I bought this ECU for $40 cash. :p
     
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