it seems like this thing reads all over the place. i could do 3 full throttle 3rd gear runs and the knock be completely diff every time 35, 70, 45 just a few numbers but whats the deal?

 

thats not good... lol

 

so is it my car, tuning, or the knock sensor? how do i know?

 

same happens to me, but only at woot in 4th gear. sometimes i read 90peak knock. if it gets this high the light on the indicator on the left side of the stearinwheel flashes red, but only for a short time, cant make out witch light it is,,,,
is it dangerous driving while the car is this way?
running basemaps

 

i dont get a flashing light, and the car was tuned and for the first few days after the tune i never saw anything above 35 but i changes plugs since then and now its erratic

 

Are you looking at knock peak hold or datalogged knock while the throttle planted? There are other sources of noise from the tranny etc that can show up as high knock and these tend to be very inconsistent. Knock under full throttle tends to repeat somewhat, if you are datalogging you should see this.

 

ive questioned the same thing ive also been told that you will see the knock level spike when shifting due to vibrations,could be wrong.

 

Drive train noise while shifting, letting off the throttle. or getting on the throttle as Kyle so stated is the caus eof most perceived knock.

Only look at knock after throttle tip in and let off when making boost runs in ONE gear.

I get higher noise readings just crusing than knock when under boost.

 

yeah i guess i have just been looking at the peak after i get done with a run so maybe it's not as bad as i thought

 

I wondered this too. In the manual it says something about it not being "of value" meaning take it with a grain of salt.
The check engine light is meant to flash when the pfc detects a knock > 60.. this indication can be suppressed in the seetings however.
I usually see more knock at low rev (round town style driving) than when giving it a hiding.
The "safe" level of knock indicated is different for different engines so what is normal for your engine may be different for another.

my 0.02

 

my knock sensor is somewhere in my basement in a box....it always reads 0

Stephen

 

so its not nesseseraly dangerous for my car???
allways scared to **** when the light flashes!!!

 

Ok, I have access to the Power Excel software from Apexi, so let me explain how it works.
The knock value is definable. That means you can set your own knock level. Apexi sets the knock value for the light at 60 on of their PFC ecus. But what the engineers at Apexi say, at 60 there is no real knock, just a slight increase in normal voltage of teh knock sensor. On a stock car ( stock turbos, exhaust etc) that means that the value of 60 is correct. What apexi told me is that 60 means that the PFC is detecting some knock activity which is not harmful. At 80 it gets iffy, at 100+ you DEFINITELY have knock, being audible or not.
Now on car swith big turbo, 4" exhaust, external wastegate, etc the knock value of 60 will not mean anything. Because the knock sensor will pick up excessive noise that is not knock, but noise from all the mods that were done to the car. The only way to fix that is by doing a datalog and recording the knock while doing a full load run at SAFE ignition timing. If you have safe timing map, and you have knock reading of 90, you can definitely reset the knock light to come on abouve 90-100. But that is done through the Power FC software, which is availble only to Apexi Power Excel shops.
So I would recommend anybody with a big single turbo, and especially external wategate, to have his car retuned at a reputable PowerExcel tuning shop.

 

I ran a single turbo at 400+ RWHP and I can tell you that 60 can be a good target for tuning. I personally saw apex seal damage twice with numbers in the 110's to 120's (once when fuel pump failed and another on the dyno playing with timing). For normal tuning on my particular car, I try to keep knock under 60, and, I found knock levels to be a function of timing advance in many cases. To amplify, if I was experiencing knock at or over 60, all I needed to do to get it under 60 was to retard timing a bit.

 

The most common reason for faulty knock sensor readings is wastegate open to the athmosphere.
Also, all cars are different, but people should consider a value of 100+ to be REAL knock.

 

Yep, all cars behave differently. I've seen some cars that show high knock all the time, had poor fitment of metal parts under the hood rubbing and knocking together.

 

Did they tell you anything as to whether the check Engine light really comes on and at what level