knock sensor issues

eckoxl

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So I've been having issues with my knock sensor for about the past year. I keep getting Low Circuit P0327. I've tried everything to fix it, multiple new sensors, rewired from sensor to the pcm, even put in a new pcm and no luck. Just for reference, my sensor is a single wire and grounds through the block. Last thing I have to try its running a tap through where it screws in. Anyone have any insight on what I could do? This is completly messing up my tune.
 

1quick

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have you verified that its seeing the power it should with an ohm meter?
 

eckoxl

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yeah i have. im going to run a tap where it screws in to clean the threads to see if that does anything. im also going to run a direct ground to the engine block; i bought my block powder coated so i think that might be part of the issue (?). and i noticed when i was logging a scan, the log would always max out at 6.73, like that was the highest kr it would see so i think its a grounding issue.
 

Aron

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When you installed the new sensors, did you torque them to spec? If you over-tighten a knock sensor it can become oversensitive. I had that problem on my car. New knock sensor, and I just put it in and tightened it up. Tons of false knock/knock retard. Found out it has to be torqued, another new sensor and properly torqued and problem solved.
 

eckoxl

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that could be a problem, ive always just tightened it snug since i was never able to find the torque spec for it. its not listed in any of the manuals i have. ill search for it, get a new sensor and torque to spec and see how that works.
 

Aron

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It's a pretty low spec, I think for the LT1 it's only like 12ftlb. If the sensor doesn't already come with it, make sure to put on thread sealer
 

eckoxl

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alright cool. just wondering, would over tightening it cause it to throw a p0327?
 

Aron

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That I don't know. My car is OBDI, so I'm not extremely familiar with OBDII shit
 

Turbocharged400sbc

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the tighter it is the more sensitive to KR, also using teflon tape vs teflon paste the tape reduces sensitivity
acording to my motor/alldata it is saying your KR sensor/coolant drain plug is supposed to be at 14 ft lbs

i know on the 3800's the L36/26 kr sensor is tighter than the L67/32 sensor spec iirc its 26 and 19 ft lbs respectivly...id have to look it up again

go ahead and clean it out with a 1/4 npt tap since the block being coated might have got into the threads...if you need you can borrow my tap and pickup this box of spare parts fer ya :s00ls:
 

6literEat'r

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i have been having this issue with my 99 trans am, and cannot figure this thing out at all, and am pretty damn sick of it pulling 4 degrees of timing all the time :(

anyways, ive read that a couple guys put new spark plugs in trying to adress this same issue and the sprak plugs resolved it..im gonna give that a shot myself! :shrug:
 

rocket5979

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i have been having this issue with my 99 trans am, and cannot figure this thing out at all, and am pretty damn sick of it pulling 4 degrees of timing all the time :(

anyways, ive read that a couple guys put new spark plugs in trying to adress this same issue and the sprak plugs resolved it..im gonna give that a shot myself! :shrug:
Are you sure that it is real KR and not false knock? There are many situations that will happen after modding a vehicle that will cause the knock sensors to trip prematurely. Noisier valvtrain, noisy supercharger, turbos introducing new harmonics into the engine, etc. If you tune your own car then try dropping 4* spark out at WOT (or the areas where you are encountering KR) and see if the KR goes away. If it does then chances are that it is real knock that was happening. If it stays the same or very close then perhaps you will need to play with the knock sensor calibration settings, burst knock tables, etc in the tune so that the false KR can be eliminated but without just totally turning off the system altogether. This may be stuff you already know but just throwing it out there in case you haven't.
 

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