Mine is usually around 120. I noticed in the summer (when i got the pfc) it was around 90. Is the knock count sensitive to weather? or is my engine going? Or is 120 a perfectly normal Max knock count on any given day?

 

When was the last time you changed your oil? Mine would drop 25% after.

 

Every car is different.

It's just the reference you use to see if anything goes wrong.

Like since your car's max is normally 120. If you see 200 one day something is wrong.

 

It depends on where the knock reading was at. Full boost, decelaration, near the torque peak, etc. I had random spikes around 150-200 sometimes which would scare the hell out of me when I saw it on the peak hold. After doing a few datalogs, I saw that my knock was around 10-20 throughout, the highest being around peak torque. I think my spikes were being caused by my transmission between shifts.

 

thanks for the help guys. i havent been able to change the oil recently. i changed it maybe 5000 miles ago (i know i know i am bad). its just a hassel in the winter cuz its not easy to work in the cold taking things out just so you could get to the oil filter and replace it. it sucks. but i will do it, and if the KNOCK reading goes down after the oil change I will post it here for other to know.

i have read some posts here where people said, if the knock is greater than 60 it means the engine is going. i dont believe any of that, and people shouldnt misinform others. my idle is extremely stable, and my car has a lot of power behind the throttle, so i dont think the engine is going.

thanks again everyone!

 

The knock sensor is garbage, dont even look at it. I hit 120-185 more than I can count.

While knock is important, the sensor is mounted in a very poor location. All the sensor is doing is picking up vibration, and its not accurate.

 

Zerobanger is right. The knock sensor picks up all kind of noise and really is not giving any sort of reliable info.


rgds

Brian

 

Go hit that loop/hook thing on the passenger side of the UIM with a hammer and see what that Knock reading says...I'm curious.

 

DATLOGIT logs have also shown that the first couple of runs will have higher knock readings. Some of this is caused by the turbos and exhaust heating up, and some maybe by loose carbon deposits in on the rotors.

 

I agree it's a relative thing...I get values that make no sense all the time and I have replaced it, tightened it, and tried to 'tune' around it to no avail.

I just for really drastic spikes now. Mine seems to be RPM dependent REGARDLESS of a:f ratio....go figure.

 

I don't know how to interpret what you guys are saying ... my knock sensor appears to be very reliable in sensing knock. I recall an event the other day when the car detonated at light load, felt like and sounded like detonation, and the knock sensor read 120! Normal runs I get less than 20 until I get near peak torque when I get some hits in the 30's and 40's (before I took out a bit of timing I was seeing 60's and 70's). A year ago when the motor blew I saw 120's to 130's with the bar shooting across the Commander face, not enough time to react. Sick feeling.

 

twokrx7

I think what people are saying is the knock sensor, by itself is not diagnostic. It seems to be reliable in that it probably does report exactly what it "hears", there is just no way that you can know what is causing the "noise" without additional information. For instance is that 120 referencing a backfire, blowing out of carbon deposits or a true detonation? You can't tell for sure until more data gets analyzed by a datalogging device. Of course then you will start questioning the sampling delays in the datalogger !

The knock sensor really is nothing more than just one more tool, and if you have had good luck making changes based on its readings then by all means continue to rely on it.

 

120 on light accel. Usually around 60 under full throttle. CJ

 

In the N8-N10 range of my PwerFC (about 3200-4000rpm) I consistently get 80-110 values and don't hear squat. I've enrichened it and it does very little (but some) shifting down.

Anywhere else , including high boost, high rpms, my knock is 20-40 ish.

 

Knock readings show 120ish spikes, but normally between 20ish and 40ish peaks. Not quite sure how to interpret. Hard acceleration shows 40ish. 120ish spikes seem to occur when I get out of the gas (blow off valve noise? backfire? who knows?). I do have my readouts on peak hold, so I can look at the peak values during the motor's operation. If anything it's just reassurance that the motor's running normally? Someone posted earlier that the knock sensor display is just to get a feel for baseline knock values, so if I see 200 or 250 knock upon steady WOT, something's really wrong...

 

The most accurate way to tell what is going on is to look at datalogit (or equivalent) logs.

I have logged spikes as high as the 180's and 190's (normal under 30), however the spikes only occur between 4 and 8 seconds after TPS returns to ~0 AFTER a period of WOT. We are all still trying to figure that out.

In the mean time, the big problems are high knock values while under WOT (regardless of duration of WOT) a high knock value at beginning of WOT can indicate detonation as easily as a high knock value upon a steady WOT.

 

I have seen my knock reading go to 120 n between shifts when it backfires.

 

Since the MOP injection system consumes a substantial amount of oil, going 5K miles without a change is a very bad idea. I hope you at least added oil!

If no oil was added you could be as much as 2 qt's low. This can drastically effect the oil temp, & the oils ability to cool the rotors (preventing hot spots & detonation).

Oil is VERY important to these engines, so make sure your level is good.

 

yup, i add oil pretty much every 2 weeks to make sure that its topped up. in addition to eating up oil, my car also drains a little bit-leaky oil pan- so i am extra careful about that. i have around 7 1 quart bottles of oil in my car at all times.