Retard Timing For Knock - Specific Question

Hi there guys,

Hopefully someone can help me understand this. I am just going through the course now. In regard to retarding ignition timing when knock is detected (assuming it is confirmed with knock detection equipment) would I go to the data log at the exact point knock occured, and adjust that specific highlighted cell by -2? Or do I select the highlighted cell and the lighter highlighted cells around it for a total of 4 cells? Or do I select the entire row? I am a little confused on that part.

Thanks for the help!

This is hard to give a specific answer without knowing what software you are using but here's a generic answer:

If you were slowly advancing ignition timing and just came into knock, then take 2 degree out of all load cells at that specific RPM where knock occurred at and above the load where knock occurred. I.E. if knock occurs at 4,000 RPM at 10 PSI boost then take 2 degrees of timing out of every load cell at and above 10PSI in the 4,000RPM column. If your RPM breakpoints are at 3,500 and 4,000 but the knock occurs at 3,750RPM then I would retard timing in both the 3,500 RPM and 4,000 RPM cells because the actual ignition timing that caused the knock was interpolated between those two RPM breakpoint.

If it is a new car that came onto the dyno with an unknown tune and knock is discovered then I would be much more aggressive retarding timing (taking out 5 or more degrees) and slowly advance timing until knock is encountered again.

Does that make sense?

Thanks @DynoDoug!

To give a little more information, I am tuning my 2008 Honda Civic SI with Hondata Flashpro. I paid a guy to etune it and the car drove like crap. Had another person off a forum etune it and the car runs great! At the start of this venture a couple months ago, I did not know anything at all about tuning or even the basics of how an engine operates. I datalog every single time I drive my car and review the logs and have been getting knock in a specific spot. Driving on the highway at around 60-62 mph in 6th gear with cruise control on and rpm is around 2800RPM. The engine will knock which I am only going off of the cars knock sensor and I have it set to flash the check engine light when it detects knock. When I see that while driving, I downshift to 5th but then the car is cruising at 62mph in 5th around 3800-4000rpm.

I was curious how the car would run if I put the stock calibration back on the car and so I did. Datalogged a normal 20 mile drive and with the stock calibration it had over 10 knock counts.

Since the calibration I got from a user on a forum would only knock 1-3 times max and sometimes not at all on drives, I wanted to start making small adjustments to get it knock free so I can enjoy my car and just drive without worrying about seeing that CEL flash lol!

Maybe you can never be 100% knock free? I am not sure and still trying to learn everything so appreciate any help and explanations!

What load is the engine under when you get the knocking? It's unusual to get knock when your cruising on the highway unless you're driving up a hill.

The car can and should be 100% knock free. Just to make sure it's actually knock and not just false positives though, run a higher octane fuel or add some octane booster to your current fuel. I get the impression the car isn't knocking very often which makes me believe the ignition timing is right on the edge of being safe vs knocking. If you're still get knocking with higher octane fuel then I would suspect false positives. My trust in OEM knock sensors is very low. If you no longer getting the knock then go back to the same octane fuel you were using previously and take some timing out at the knock point.

Some cars do run very aggressive timing from the factory to get maximum efficiency and then rely on the knock trim to retard the timing and keep the engine running right on the knock threshold. I'm not familiar with Hondas to know if this is the case for your car.