28 pages of posts later and no solution. My 2010 3.8 has the spark knock issue. I installed a new engine and it still has the issue with a completely different professionally built engine. I have replaced all the sensors including the O2 sensors. I have installed the Demon coil cables and double platinum plugs. I have used all sorts of fuel additives including a cat cleaner. Have also cleaned the throttle body. Also tuned with a hypertech programmer at 87 and 91 fuels. I am currently messing with a Diablo tuner. I have also had the dealer reflash the PCM. I am at wits end. Maybe there is no solution for this. My last option is a custom tune that will adjust timing. Any suggestions?

 

I do my own tuning with HP Tuners software, and it took around 3 degrees less spark advance at certain points in the tables to get rid of the audible pinging with 87 octane. The engine does (and should) still experience ~3 degrees KR (knock retard), which is proper to have the best power/economy with a reasonable range of compensation for different fuels, temperatures, and engine loads.

A key point is that logging some KR (from spark knock) is completely normal and expected -- one might hear just a bit as the spark is quickly retarded in response to spark knock. It's only problematic when the engine has so much spark knock that it can't retard it enough that it becomes continuous and/or loud.

Since higher coolant temps promote spark knock, I also set the fan to come on earlier, but with a tighter deadband -- Essentially the temperature variation on the high side is less. There's a few more tricks as well. If you want to go the HP Tuner route I can give you some help, but here's a few other thoughts:

The base timing is set by the relative position of some protrusions on the flywheel and a sensor in the bell housing. I don't know the manufacturing inaccuracies, but there has to be some variation with some engines being a bit more advanced and thus more likely to have this issue. Compression also varies a bit, and higher compression is more prone to spark knock.

If the EGR valve ports are restricted, this will result in spark knock especially in the mid power range. An example would be cruising at 45 on a level road, then adding a little throttle results in audible spark knock.

Try some 92 octane fuel. Shell is my favorite, probably does as much to clean the injectors, valves, etc. than additives in a bottle and you get more octane too. If that doesn't make a noticeable improvement, it's not really spark knock that is being heard.

The knock sensor may not be working. If you can hear it, and it's real spark knock, a log should show KR detected -- with immediate reduction in spark advance.

 

My 3.8 would constantly ping pretty much from new. If I used higher octane gas it basically went away. (My 2004 4.0 did the same thing). I had the spark plug wires and plugs replaced at 90K (I know far too long) and all the pinging went away and I could use 87 again.

 

Factory manual suggests plugs and wires are good for 102k miles. I don't subscribe to that theory because plugs are cheap and pulling them early ensures I won't deal with a seized plug.