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

[EagleMark]

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!

[CapriceLT1]

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.

[CapriceLT1]

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)

[EagleMark]

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.

[CapriceLT1]

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 :'(

[EagleMark]

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.

That's the procedure for that circut, you've already done the advanced part which was replace PCM, knock module or Knock sensors. I know you said you checked wiring, but do the voltages and ohms. Being you have replaced the wires, plugs and PCM, probably check ohms on knock sensors first. Even though IIRC new they could be faulty or wrong units!

Has that LT4 knock module you put in there ever worked? Does the LT4 module swap require LT4 knock sensors? Remember I said to pull it and look at pins in PCM and pull white cover off module to see sockets in module? Or just slip the origanal back in too?

EDIT: Conflicting info? LT4 is OBDII which requires differant knock sensor, but everone is using OBDI knock sensor with LT4 module. So the differance must be in PCM.

But! Tests for knock sensor ohms is differant from OBDI to II... and part numbers differant?

OBD-I (1993-1995) knock sensor GM PART # 10456126 ACDelco #213-96OBD-II (1996-1997) knock sensor GM PART # 10456287 ACDelco #213-325

so conflicting to me as test is:

Key OFF. Connector off at the knock sensor. Measure the resistance between the KS terminal and ground. Resistance should be between 3300-4500 ohms (OBD-I) or 93k-107k ohms (OBD-II). If it is not, the sensor is faulty or the sensor is not making good contact with the block. Try another resistance reading from the sensor terminal to the outside metal of the sensor body

In reading this it may be a ground issue with sensor to block as well.

[CapriceLT1]

LT4 module swap DOES NOT require LT4 knock sensor. The pins are the same. what did you mean in the first quote? how do i test the sensor for 2.5 if both are connected?

"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."


I am going to have my dad help me with the electrical tomorrow since its not my best area in the automotive field, add some grounds, test the circuits and wiring etc