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No need to wire knock sensor?

Discussion in 'ECU's, Electronics, and Tuning' started by caddytwix, Oct 9, 2005.

  1. caddytwix

    caddytwix Junior Member

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    Just wondering if anyone ran into this before:

    Have the JDM p30 and got everything running, new that vtec would NOT engage because knock sensor not wired it up (doing test run).
    Well to my suprise, vtec DID engage without the knock sensor wired. Weird huh? guess on some of them the knock sensor is disabled.
    (i know because i heard the cam changeover, and have the LED attached to the vtec solenoid)
     
  2. eg6sir

    eg6sir Supa Mod Moderator VIP

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    its probably grounded off the ecu somewhere other than the block itself, because you dont need to wire it...you'll just have a CEL..it only has to be grounded
     
  3. caddytwix

    caddytwix Junior Member

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    CEL is off and no codes. Although after driving for a while i sometimes get a code 20 for the ELD and my idle fluctuates, but i believe that is a seperate issue?
     
  4. tylonalsnifnfool

    tylonalsnifnfool Senior Member

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    I ran my car without the knock sensor wired for 2 days with no ill affects. VTEC kicked and I had no codes. I ended up plugging it in just for peace of mind though.
     
  5. reikoshea

    reikoshea HS Troll...And Mod Moderator VIP

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    My timing retards on my H22 w/ P13 when i get a KS. Vtec will still engage, but you dont get much benifit when your timing is set to zero (instead of 16)
     
  6. dohcvtec_accord

    dohcvtec_accord WRX Sellout

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    VTEC will work without the knock sensor hooked up. As reikoshea said, though, the ECU will retard your timing if it's looking for a knock sensor and can't find one - it will act like it's finding knock all the time. However, it doesn't affect your timing by 16 degrees, though. That's huge! [​IMG] Probably a couple of degrees.

    Is the JDM P30 supposed to look for a knock sensor? Maybe it's already been hacked to not look for one?
     
  7. reikoshea

    reikoshea HS Troll...And Mod Moderator VIP

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    I swear...i drove it around the block and came back...it was at 0...random ass shit.
     
  8. dohcvtec_accord

    dohcvtec_accord WRX Sellout

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    Sounds like you forgot to tighten some of the distributer bolts back down. [​IMG]
     
  9. eg6sir

    eg6sir Supa Mod Moderator VIP

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    not to treadjack or anything..but i wired up my knocksensor and i am still getting the code...but the way i did it..i just spliced it into the wiring harness right behind the motor....so my next question is ....could the knock sensor be bad..i am gonna run a wire straight to the ecu and see if i still get my code, if i do the sensor is most likely bad, right?
     
  10. dohcvtec_accord

    dohcvtec_accord WRX Sellout

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    What car is it? It's possible that the wiring harness isn't pre-wired for a knock sensor. Like you said, try running a wire straight to the ECU. That's what I did, with no problems afterward.
     
  11. eg6sir

    eg6sir Supa Mod Moderator VIP

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    its a 94 hatch w/ sir2 .. usdm p30 ecu....there is a wire in the d3 pin for the knock sensor, im just going to cut the wire up underneith the dash and run the wire from the KS plug to the wire under dash...sound about right?
     
  12. teglovinvtec

    teglovinvtec Junior Member

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    i have a da with a b18c1 swap i didnt have knock sensor for awhile and yea vtec still kicked in good but my gas milege was poor bc of the retard timing so i would add one when ever u do a vtec swap.
    note: if u cant get a knock sensor plug use a green temp connector and only use one wire since its a one wire sensor. i had to do it this way bc i didnt have a connector. bottom line it works just make sure u use the right wire on connecter since sensor is one prong not 2
     
  13. TeamUrbanChaos

    TeamUrbanChaos Certified H22 Super-tech

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    is there really a need for a knock sensor anyway?? i mean, as long as your car is timed right and you dont use cheap gas, theres really no need for the knock sensor?? and i dont think it does anything for performance correct??......i dont have a KS on my H22 and my ECU dosent look for one anyway (p28) but it just seems to be so much more of a hastle having it hooked up then not having it hooked up at all. even the slightest ping will cause the KS to kick on and the whole car will go into an open loop mode and whats even worse is, lets say the cause of the KS to come on is becuase theres water in the gas. its not gonna reset itself unless the tank is empty or the car stops pinging from the diluted gas. sucks if you got a full tank too!!!!
     
  14. dohcvtec_accord

    dohcvtec_accord WRX Sellout

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    What??

    So, you wouldn't want a knock sensor protecting your engine if you had water in the gas tank? Also, a detected knock will cause the engine to retard timing (and possibly dump a little more fuel), but it will eventually go back to a "normal" timing/fuel map.

    Come to think of it, will watered gas even cause knock?

    Anyway, I know that I like the added protection of a knock sensor, as do other people. If it's functioning properly, I'll take one any day.
     
  15. reikoshea

    reikoshea HS Troll...And Mod Moderator VIP

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    I wish mine wasnt so bad. i took off the head a couple weeks ago and my cylinders are perfect. i get a ks EVERY TIME I DRIVE and i cant even drive the thing the way i want to. just sayin...in my case its caused more harm than good.
     
  16. caddytwix

    caddytwix Junior Member

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    K after driving for 3 days, I finaly got a Knock Sensor code.

    So you're saying that if it looks for a knock sensor and doesn't find one, then it will retard the timing? That sucks.

    Well I have a P28 chipped, but i need to order new chips because i burned them at the wrong voltage (oops!)

    Well, just another 1 of 100 different little things i gotta do to my car...
     
  17. reikoshea

    reikoshea HS Troll...And Mod Moderator VIP

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    P28 doesnt look for a knock sesor does it? id really hope not if it was chipped too.
     
  18. caddytwix

    caddytwix Junior Member

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    Sorry, i meant I have a chipped p28 but im not using it, im using my jdm p30
     
  19. TeamUrbanChaos

    TeamUrbanChaos Certified H22 Super-tech

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    thats exactly what i mean...everyone i kno has all had bad experiences using the knock sensor. the slightest problem form off timing to moisture in the gas causes this think to engage. it sucks
     
  20. dohcvtec_accord

    dohcvtec_accord WRX Sellout

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    FWIW, I never had problems with my knock sensor. It was the one that came on the engine, and I hard-wired it to the ECU.
     
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