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Thread: Tuning out Knock Sensors to get rid of code 43 in my 95 LT1

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  1. #1
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    Tuning out Knock Sensors to get rid of code 43 in my 95 LT1

    I have had a code 43 in my 1995 Caprice 9C1 (LT1) and have put in new sensors, sensor connectors and bypassed the harnessed and wired the KS to the computer, bought a new ECM. I started putting ground straps everywhere and it STILL wont turn off. Its been going on for months now and I cant think of anything else except add more straps. Everythings torqued to spec and wires are right. Is it possible for me to use tunerpro RT and disable the KS so my light will be off? Sure i risk detonation but I have been for the past 6 months at least becuase nothing i have done has worked. Getting 9 mpg in something that can get up to 20 if i behave like i did before is not good for the wallet and with it not working anyway it cant be good for the car

    leadfoot from impalassforum.com said this:

    "My race 409 was blowing them all the time. Code 43 pulls 5 degrees of timing, mine would run at the track, just fine, plus my tune has KR disabled at WOT, anyway.

    Too much effort to chase issues, I just had my tuner disable code 43 in the PCM. I've never had detonation issues, but I do run an additive, just for safety's sake.

    Might not work for you, but I don't get the CEL any more."




    what do you guys think and how can i do it if i can do it? Iv thrown a new ECM, Knock sensor, wires, connectors, knock modules (stock and LT4) and it wont go away. To tune it out or not to tune it out?
    Last edited by CapriceLT1; 06-08-2012 at 09:14 PM.

  2. #2
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    Have you cleared codes either by scan tool, TP or removing power from PCM? I don't remember where you were and don't want to confuse you with someone else...

    Sure, look under flags for "Knock Sensor Diagnostic, Error 43 " and uncheck. This will disable the code 43 CEL light only and not the knock system.

    If you go further to disable Knock System Retard for timing I would look at data logs first to see how much and where knock is and how much spark is being retarded!

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  3. #3
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    Your not, I am the same person on impalassforum lol. Just trying to get as mush info as possible since I haven't gotten anywhere in the past few months. I have cleared the codes with my friends MAC tools scanner at his shop, disconnected the battery for a few hours while working on the car and it still comes back no matter what. The only thing that I have come up with is to keep adding grounds. But thats it. Next post will have a 45 min log (long i know but i watched most of it since im still learning and curious) and it with NEW ecm, wires, KS connector, old/new KS and wiring. I have new KS to install and I am just going to defect the ones I have now. Maybe I got bad sensors? I changed one and got nothing, code still there.

  4. #4
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    I dont think it was 45 minutes but this is with the new ECM (computer) and moving the ground that is comes off the negative battery terminal (the ninja star ground)
    Attached Files Attached Files

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    Looking at data does not show any ground issue, but you do have issues! That code 43c active seems to be messing up everything! Looks like a limp home situation as your closed loop, right and left O2 ready but BLM is not enabled so it's 128 BLM always, open loop. Also spark retard is pulling spark whenever you accelerate although there are no (once) knock counts. Both fans always on and never TCC lockup. So big issues!

    To check knock wires there should be 5 volts on wire key on wire disconnected from knock sensor and about 2.5 volts connected, each side. The code sets if the voltage is outside the range of 1.5-3.5V.

    To check knock sensors use an ohm meter and pretty sure they should be 4900 ohms to ground.

    This is what data log is showing, same code has three MALF flags 43a, 43c and 43d... so turning off CEL is not going to help anything except the CEL off when it's really telling you something is really wrong and making the car run really bad.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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    It is running really bad. 02 sensors are new. I know turning the CEL off wont fix the problems lol. So fix the knock sensors and everything else should be ok? But thats what iv been trying to do. Not many people have stepped up. I will check all the connections and give you the readings tomorrow and we can go from there i guess. I just want her to be back to normal again :'(
    Last edited by CapriceLT1; 06-09-2012 at 05:57 AM.

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