Hondata

My car knocks in the area of 2500 - 4k rpm quite a bit under boost. I've even tried pulling 5 degrees of timing in that range (verified in a datalog) and it just keeps knocking. I think it's real knock as it only happens at 'full boost', which with my pulley is around 5-7psi down there, and it doesn't happen at light boost or part throttle. At first I thought I really had some nasty gas, but I've got a new tank since then. It doesn't knock where there's methanol spraying (4500+ above 5psi). I'm about to go get a cheap ear piece and listen to the knock sensor. I've checked the plugs and I don't see any signs of damage to the grounding strap, electrode, or insulator.

Hondata: Do you have any suggestions / ideas what else this could be. I'm tempted to just move vtec to 3k and see if it just seriously disagrees with that much boost on the low cam for some reason.

Really frustrating.

Almost any audio amplifier connected to the knock sensor input will tell you. I used to use a set of cheap PC speakers, with some J connectors soldered onto the input cord, a power outlet adapter, and some headphones. Now we use a professional knock sensor amplifier with dual inputs and band pass filters etc, but it does the same job.

Real knock is distinctive - it sounds like a strong 'tick' noise over all the other noise (valvetrain, alternator, injectors). Usually you get a burst of 2-10 knocks over about a second or so.

Usually once you get bad knock at low rpm you'll end up at 5-10 degrees total timing to get rid of the knock, so you may need more retard. Also remember that winter fuel is horrible for detonation resistance - the RON rating is not very indicative of knock resistance; MON is much better, but octane rating does not measure the actual detonation resistance of the fuel very well. Use C16 and you'll see what I mean.

Hondata wrote:Almost any audio amplifier connected to the knock sensor input will tell you. I used to use a set of cheap PC speakers, with some J connectors soldered onto the input cord, a power outlet adapter, and some headphones. Now we use a professional knock sensor amplifier with dual inputs and band pass filters etc, but it does the same job.

Real knock is distinctive - it sounds like a strong 'tick' noise over all the other noise (valvetrain, alternator, injectors). Usually you get a burst of 2-10 knocks over about a second or so.

Usually once you get bad knock at low rpm you'll end up at 5-10 degrees total timing to get rid of the knock, so you may need more retard. Also remember that winter fuel is horrible for detonation resistance - the RON rating is not very indicative of knock resistance; MON is much better, but octane rating does not measure the actual detonation resistance of the fuel very well. Use C16 and you'll see what I mean.

If I retard much more, I'm going to be in the negatives for ignition values under boots -- is that acceptable in your opinion?

Once you get below about 10 degrees timing the EGTs rise. Below 5 degrees would be ok for tip in. First find out if it is real knock.

Hondata wrote:Once you get below about 10 degrees timing the EGTs rise. Below 5 degrees would be ok for tip in. First find out if it is real knock.

Damn -- I'm already around 2-4 degrees in some places. The base map even has negatives in certain places.