I have been tracing down some false knock forever now, I have replaced quite a few sensors(knock sensor) and I still have it. Like while cruising at 40mph and giving it a little gas the knock retard will jump up to 13º and slowly work its way down. Also while sitting at the light I had my AC on and the knock retard would cycle from 1.9 and work its way down and then idle at 0.0 for a little bit and then go back up to 1.9. It is dependent on the AC because I turned it off and no knock retard showed up.

I know my O2 sensors are bad, they been bad for a while, and I have gotten a code for the Bank 2 being to lean, I think P0174 or something. But would faulty O2 sensors be causing knock retard and causing the car to misfire and overall run bad? I've even noticed under full throttle the car would pop through the exhaust, have knock retard and misfire.

I also got a P0300(random cylinder misfire) and a one for the MAF sensor being disconnected and TPS voltage too high and too low. But the MAF code and the TPS codes are from my messing with my holley 58mm TB(finally got it to close 100% and adjusted the TPS to .64).

 

well, running too lean means you're running hotter than normal. hot cylinders cause preignition which causes PCM to pull timing. the fact that you have EGR deleted as well would keep cylinders from cooling during cruise. i mean, the O2's are only part of the fuel metering system. if you know there are other problems with the car why wouldn't you go ahead and fix them anyways before chasing down a problem such as mysterious knock retard? doesn't make sense. having problems fixing one issue? try fixing others and your problem may "magically" disappear. especially when they are each part of related systems.

 

I have been chasing down the false knock for a few years now. Ever since I installed my scanmaster and became aware of the knock retard. I have installed new O2 sensors since then and I still had the knock retard. I took it to the dyno a couple years back and messed around with the timing to make sure it wasn't advanced too much for 91 octane and that wasn't the problem, got an awesome tune out of it though. I'm running about 37º at WOT.

Today on my way to work I gave it some gas and I could just see the fuel pouring out the exhaust pipes. It smoked better than my diesel.

 

If you only get the knock with the a/c on, perhaps it is doing a lot of rattling to cause it. It's in close proximity to the sensor.

 

I was saying it would pull timing at idle with the AC on. It pulls timing randomly while drive with or without the AC on.

Today I pulled the codes and I got a P0300 random misfire and a P0174(I think) bank 2 sensor 1 low voltage, which would explain the bank 2 side running lean code. I cleared the codes at work and on the drive home they popped up again.

It's driving me nuts. Hopefully it is related to the O2 sensors cause I am replacing them yet again this weekend with some AC delco's, just waiting on the extensions. Before I had some cheaper O2 sensors(forgot the brand) and homemade extensions.

I'm hoping I didn't foul my spark plugs, running too rich or too lean, cause they aren't that old and they are NGK TR55i Iridiums, so they are not cheap to replace.

 

Have you had the headers long? They can cause knock to show up and its worse if you have exhaust leaks that can be heard.

 

I've had them for 3 or 4 years now. Did the LT4 knock module and I'm pretty sure i went in and desensitized the knock tables while on the dyno. No exhaust leaks that I know of, but I had planned on checking this weekend and while I'm in there I will pull a couple plugs to see what they tell me.

 

I've also checked up around the knock sensor/starter area making sure no high voltage wires run too close to the knock sensor wires.

 

I have had timing pulled like this before.

 

Because of an exhaust leak?

I know its possible for the knock sensor to pick up an exhaust leak as knock, but I'm pretty sure I don't have any leaks. I know I didn't last time I checked and I don't know why one would show up all of a sudden like this(the headers have been through enough heat cycles by now).