when i'm driving around, at part throttle i'll get various amounts of knock retard from approx 0 to 14 degrees at times. Sometimes it's so bad when i give it gas I feel the car stumble from all the retard. At WOT, the retard never goes 14 but it still hits around 6 degrees. What could be the problem here?? I'm running premium, I ordered a set of new plugs and will check the wires when I change them. I have some NGK coppers in there now that have been abused with juice for prob 30k miles... Anything else I could check, would bad plugs cause that much retard?? This started a few months ago and got progressively worse until now the car is actually stumbling from the retard it's so bad......

Thanks
Brian

 

You do have the LT4 KM right?

 

Yes I do, also running STOCK timing curves, PCM is stock configuration.

Car is also running proper air/fuel ratio verified by scanmaster.

 

Do a board search and get the resistor that is called for and install inline with your KR sender. Do this only if you think it is false knock like header noise, aftermarket valve train,ECT. LT-4 KM doesn't always cure anything but the resistor will if it is false knock.

 

After getting my car back together, I was suffering from knock also. Car felt severly underpowered. I have a LT4 sensor, but was still getting knock. Turns out my intermediary pipe was hitting my axle. I wrapped sume rubber in heat wrap and put it in between the pipe and axle--car felt 10X stronger. Drive around with your windows up / radio off and listen--that's how I caught mine. You can also try to boost up your octane to see if it is true knock.....

 

BAD IDEA!!!

First of all, put RACE GAS in the car and then monitor your knock sensor...if the knock goes away with the race gas, then the knock is real knock and you most likely have something else going on.

If the problem does NOT go away with race gas, then it is false knock. Still, that knock sensor is there for a reason..if there is a time where you need that sensor and it is desensitized, say goodbye to your motor.

Just my .02

 

i think you have it backwards

 

I think Dubby is correct. More octane corrects true knock. If octane does not correct the retard (knock) then it is a false knock and there is a reason other than low octane gas creating the retard (knock).

 

How does yours show 14 degrees? Mine only goes up to 8.0 degree's. It always stops there.

 

Actually, I do not...

 

The ScanMaster can show any value the PCM sets.... there is no limit of 8deg for knock retard in the ScanMaster. It's possible your tuner (madZ28) has put a limit of 8deg on the maximum amount of retard the PCM can apply.

Check your knock sensor. I've seen cases where crud building up in the bottom of the water jacket puts solids in the sensor and increases its sensitivity. I would also try the high octane (non-leaded) fuel, to see if knock is reduced. And obviously, listening carefully for mechanical noise might point you to a problem.

 

Would the crud build-up be externally. Come to think of it, does the Knock Sensor extend to the interior of the block? Would it help reduce the sensitivity of the KS if you were to wrap the KS with foam or something to reduce the sensitivity of it?

 

I am having the same problem. I am getting about 12° or knock retard. I added 5 gallons of 100 octane to my 1/2 tank of 92, and the knock retard is still there. At idle I am getting about 1-2, and as soon as I give it some throttle, it zero's out. I think because the motor stops shaking (big cam). But once I accelerate over 3500, it shoots all over the place. I think I am going to desensitize the knock sensor...

 

The knock sensor is a piezo microphone. It screws into what originally was to serve as the passenger side block drain hole, so the end of the microphone is exposed to the coolant. Any solids or sludge that builds up at the bottom of the engine coolant jacket can plug the knock sensor. I remember one specific case with huge retard numbers, and when they pulled the knock sensor out, it had a chunk of RTV from some previous engine work stuck in it.

You can supposedly reduce the sensitivity by wrapping the threads with Teflon tape and not tightening it to the full torque spec.