Just been out for a run and got a peak knock reading of 43, normally I only see about 7. I also have a knock link but didn't get to see it at the time.

What would 43 equate to on the knock link? and how much knock is acceptable from a JDM WRX with full decat?

 

I tend to sometimes notice a high knock on a warm day...though normally averages under 10...

Up to 17 can be considered road noise, i have seen higher numbers caused sometimes by gear change and these i ignore.

Anything above 17, i would consider as det.

Does your knock show up consistently or is it at random?

 

Depends entirely on the engine. My engine with forged pistons that are a little rattlly would be det free with a knock reading of around 45. However for a car with quiet pistons I would be wary of anything in the 20s.

Be aware that you may get a single spike in the knock as you change gear or lift off sudden when at high boost. This is a common problem on foctory ECU too, if it's only once and a while I wouldn't worry about it too much.

If you have a 97/98 car then you may get higher knock figures due to piston noise, although some will be better than others. The only real way to check one way or the other will be to listen with det cans.

Paul

 

I reset the peak hold on the commander and got 33 the next time, its a jdm MY97 which has some piston noise/slap - so hopefully its that. I guess it could be a combination of a bad batch of fuel and air temp. I might try a few mls of Nf tomorrow.

 

Maybe irrelevant, but I was getting near 72 knock, though I eventually found this to happen under Certain load and RPM…took out a degree out of the engine advance at that location and all was ok…

Paul: Cars driving ok now...

 

Put the commander in graph mode and just monitor knock, if the engine is generally noisy then the level will increase nice and steady with increased rpm. If you boot it and it rises slowly but has a big spike to 33 or 43 or what ever you were getting then i'd be a bit wary. The graph mode is very useful rather than just looking at peak values.

Also useful is the inj/ign settings, knock a few degrees off the map using this and go out and boot it, if there are no spikes then you need to look at the map more closely.

Tony.

 

Good news!

When you see peaks of over 50 that's definitely detonation, as as Sam mentions he took a degree of timing out, based on the datalogs of where the PowerFC was hitting the map on full boost (datalog from mapping session with me).

 

Andy puts the CEL on at anything over 40 even when apexi recommends 60. When he mapped my engine he heard no det even when a gearchange or lift saw up to 60 on the knock on the powerfc.

Just like Pavlo says it all depends on the car and that is why mappers map your car with det cans so they can make sure peak readings like these are not true det that would no doubt in time kill your engine.

Stuart