knock spikeing
 

I recently installed a powerFC in my FD. Everything has been great other than wierd knock readings I've been recieving.

I've heard from multiple people that the knock readings on the PowerFC are flaky, and the numbers shown really don't amount to much. But I would think my numbers should be similar to other FD's

For the most part my readings are similar. rarely raising above the 40's

But I'm getting knock spikes when I hit approx 2500-3000RPM. They happen most often when I push the clutch in with slight acceleration before breaking to slow down. This happens most in 1st or 2nd (example: slowing down for a speed bump or stop sign) and I get spike readings of 59 - 79. It's hard to do this in the other gears very often. but I was in a similar situation in fourth or fifth and I got a spike of 188! The 188 spike was on bad gas (still 91, but olympia) and I have since changed to chevron. which has dropped the average knock readings down, but not the spikes.

I've been told not to worry about it, because during these times, I'm not applying a load to my car. But I want to know what everyone thinks.

Can this be fixed with fine tuning of the powerFC? Should I replace/clean my fuel filters/injectors? Am I being neurotic?

TIA

Greg.

If you do a search in the Pfc section under
"knock readings, not the usual question"

You'll see I had the same question.

No load, 2500-3000 rpms my reading go above 130. I torqued the sensor & even bought a new one. No change in the reading.

My motor is strong & under boost the knock readings drop to under 50.

You could buy a J & S knock sensor & compare.

when did you post? I did a search recently and couldn't find anything similar. so no solution for you either huh?

I get high knock readings on decelleration while still in gear sometimes close to 100, usually up to 60 or 70.

Occational spikes in the 160 range in the 2500 - 3000 rpm range under light acceleration as well.

I always use Sunoco 94 and haven't worried about it since my car has been on the dyno w/wideband many times and I know my a/f is safe and it isn't real knock, probably just other random vibrations, possibly from pulleys or exhaust, etc.

K

"not real knock"? would you mind explaining this a little bit more?

like false readings because of resonance or some other vibrations?

Exactly! I wouldn't call them false readings, they are noise readings that "sound" like knock to the sensor caused by something other than engine pinging, detonation or otherwise "knock" as we know it. :D

K

ah... you put my mind at ease.. thanks K.

Greg

I have higher knock reading crusing around then I ever do slamming though the gears...always see a 40 or so..sometime higher... I pretty much disregard it for the most part.

Let's hope you guys don't regret ignoring it if det. occurs. Not that it will...;) right? :p:

as long as my car doesn't start sounding like you're screenname... I'm cool :D

but seriously.. that was why I posted this in the first place. my situation didn't meet the standard detonation critera, but I was still concerned on whether or not it was still a posibility or if my readings were an indication of that.

Have tryed retorque'n the Knock sensor it might help with better readings but do not get alarmed I heard once you knock you knock Just beacause you have a Knock sensor does not mean it will ketch it before it is too late and most of the upgrade ecu's just bypass the knock sensor to run higher boost and so they make it a real rich A/F ratio.IMO from what I have been told by certain shops wont mention anynames though:)

-Ryan

true... but knowing a regular healthy pattern for your car will help you to see deviations leading up to detonation. Like I said.. these spikes occur under no load and usually in 1st or 2nd gear. Now if my AVERAGE knock readings go up and I start getting boost spikes in other loacations (under load, acceleration) then I'll know there is something wrong. like with anything else, it's just being familiar with you car.

Well not really Sean(whiterxseven) got a pfc and every time he revs it the meter just jumps. these knock sensors are very generic and pick up any kinda vibration from the exhaust rattles to the the battery move'n around to much(dont ask me how I know that it is silly)
and anyone will tell you not even to bother reading it as it is useless:(
sorry dude but it is the truth

the readings themselves might be useless. but what I'm saying is just with anything else. Deviation from what usually happens will tell you SOMETHING isn't right. even if the numbers don't mean anything and your readings aren't the norm, if there is regularity or a pattern in your readings you will be able to notice deviations from that pattern. If the deviations are large enough, or appear in areas which have traits of detonation, then I'd have them checked out, or checked on.

just like you know the rattles and nuances of your car. if you hear another rattle that your car, you're going to look at it right? not just say "well, my car rattles, so there's no reason to find out where it's coming from"

good point
well taken:D