Sup People



I was just wondering what is a safe number on the PFC knock sensor, I hit a high number of 157 with .90 boost. The car did run strong and I had no problems. The reason for me getting on it hard was an S2k on my right side , but not for long. That was fun https://www.nopistons.com/forums/pub...#>/BURNOUT.gif



Alex

I think the knock numbers on the PFC are kinda arbitrary, as some people always see higher numbers, and some people never see higher numbers. I think the biggest point to remember is that the knock sensor is a worthless turd. By the time it sees enough knock to decide to retard timing, the engine is already gone.

the knock sensor is a fancy microphone, so it might also be picking up something loose under the hood



mike

Correct me if I'm wrong but I thought the ignition retard "safety" goes with the stock ECU when using something else. The PFC does not have it, or does it?

The safest thing you can do is get it tuned safely.

Or you can go fancy and get a j&s knock retard system(although i dont know if theyre any good or not).

Then again, what the hell do I know https://www.nopistons.com/forums/pub...#>/biggrin.png Oh yeah, if you had detonation, you wouldnt be asking about the safe #....instead you'd be asking how long for the rebuild/when do i get my car back https://www.nopistons.com/forums/pub...DIR#>/wink.png

All of you have good points, I guess I won't dwell on it and just worry if I hear a loud boom.



Thanks,

Alex

The knock sensor is essentially a big microphone. The PFC has the knock/timing retard feature turned off so the number is completely arbitrary. If you drive around watch your knock. If it averages 100 knock BELOW 0 psi, then that's normal. If you hit 115 doing a run, then your safe. If you hit 150 knock then your knocking....about 50 over your normal knock means detonation.



Contrary to popular belief, you can knock and still have a running engine. It does not take 1 knock to do it. It CAN take 1 knock, but I doubt it. While tuning my FD, It took me a few trial 1,2,3 gear runs to get the fuel mixture just right. While I was doing that, I was seeing knock as high as 100(my average is 17). I tuned it down and now it's back to ~20 knock.



According to the PFC manual, it says that anything over 50 is considered knock.

Its useless. The sensor can be picking up any kind of noise and the engine not really be detonating. I see it tends to register higher in my car on decceleration. I don't really pay attention to it and rely on tuning to keep me safe.

That's why you use DATALOGIT! They've got the min/max/average knock feature to see where or if it was even knock. I look at the maximum knock for that particular block, then check the minimum, then go to average. If the average and the maximum are closer to each other, then I turn the fuel or and/or retard the timing 1 degree. https://www.nopistons.com/forums/pub...IR#>/boink.gif

Knock retard can be useful, but you should use wide band o2 & dual egt's (one per rotor on a 2 rotor) for tuning. The knock sensor(s) will pickup all sorts of crap, road noise can even do it.... the thing is though, knock retard won't break things, it just makes less power due to retarded timing. Lack of knock retard can break things where having it may have saved your ass. So your computer thinks the engine is knocking when you go over that nasty ass street road, you lost some horsepower due to the retarded timing.... oh well, I doubt you were trying to go fast anyways... at least in the event of real knock it just might do some good.



*shrug*