# Whats safe 'knock' level on Power FC commander?



## leggus (Feb 15, 2006)

Had Power FC mapped up to 0.9 bar, couldnt go any further because the boost controller was'nt working properly.

Fixed that now, and on the way home i gave the car a little squirt @ 1.2 bar (GT-SS turbo's) but the warning light flickered for a second at about 7000 rpm.

On the hand commander, the stuff being monitored is, Injector duty, Air Flow, Timing, and Knock.

I glanced at the commander, but obviously because i'd eased off, i didnt know which one of these readings caused the flicker, but i presume it was the knock sensors.

Ive turned the boost down to 1.0 bar and have been monitoring the knock level meter all day, and it doesnt seem to climb much higher than a quarter of the way up the scale.

Does anyone know the 'safe' zone for the meter reading?

i.e., how high can it go before it all gets a bit dodgy?

And can you get a peak reading from the hand commander after you've finished your journey? If so, how?

Thanks in advance.


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## leggus (Feb 15, 2006)

P.S. Injectors are 700cc and AFM's are Z32.


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## coxie (Oct 23, 2003)

ohhhh...good question i too would like to know how to get the peak reading feature to check injector, afm and knock....

anybody any ideas 

p.s sorry to jump on this thread....


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## Nick MW (Aug 15, 2003)

On the hand controller you can select all readings to show peak only - from memory when it was on monitor and it was one of the arrows that moved it to this??

Mine only ever used to hit about 32 after a really hard play when it was set up properly.


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## leggus (Feb 15, 2006)

Cheers Nick, i'll have a mess about with it tomorrow.


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## turboshed (May 5, 2006)

You have to press the up arrow to show peak readings


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## markyboy.1967 (Feb 14, 2004)

*Knock*

Yip the up arrow shows your peek figures.. Almost had a heart attack when i saw my knock hitting 113 on the monitor before i found out this was just from the engine turning over at start up ...


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## coxie (Oct 23, 2003)

thanks for the advice guys really helpful...have a beer:clap:


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## leggus (Feb 15, 2006)

Echoing coxie's comments, thanks for the advice guys.. and yes, definitely time for a beer


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## purplepower (May 26, 2005)

My warning has been set at 40 which is still fairly conservative. IMO, Anything over 60 needs investigating


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## skyline69_uk (Jan 6, 2005)

markyboy.1967 said:


> Yip the up arrow shows your peek figures.. Almost had a heart attack when i saw my knock hitting 113 on the monitor before i found out this was just from the engine turning over at start up ...


I sh*t my pants the first time that happened too pmsl!


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## skylife (Dec 6, 2005)

yeah anything under 60 and your fine.


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## Pavlo (Sep 12, 2002)

Absolute bullshit.

There is NO safe level of knock on a PFC because every car is different. Some cars will see knock levels of around 25 on light detonation, some cars will see "knock" levels of 25 purely from engine mechanical noise.

You need to look at the trace of knock over time, preferably with a laptop using power excel or Datalogit. You need to know what sort of knock levels YOUR engine exhibits when it actually dets, so get some det cans and have a listen.

Paul


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## Pikey (Feb 19, 2004)

Typically, the warning is set to come on at 40 if you're being conservative, 60 if you're not.

I monitor speed, knock, intake temp, and water temp, with peak values on (by pressing up). If you press the right arrow, you get a real-time plot of the values you've chosen to monitor, but it's all but useless other than looking pretty cool to impress your passengers :clap: 

It does sometimes pick up the starter motor noise and registers over 100 on startup - I tend to switch off and start again if it does that, as your peak value becomes useless for the rest of the journey.


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## Pikey (Feb 19, 2004)

leggus said:


> i didnt know which one of these readings caused the flicker, but i presume it was the knock sensors.


The only warning that flashes the ECU light is knock


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## coxie (Oct 23, 2003)

i have a laptop where do i get a copy of the software needed to access the ecu via latop???what do you use to connect to the laptop ?cable wise?


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## Luckham (Nov 10, 2005)

Pikey said:


> The only warning that flashes the ECU light is knock


Not true matey - if your afm's max out the ecu light on the dash also flashes [but slower] [assuming you still have AFM's that is!]
Also you can re-set the max reading by going to real time mode and then going back to peak reading..

I really wouldn't worry about any reading below 30ish - also bear in mind that the PFC det monitor is pretty inaccurate anyway, and as pavlo so eloquently said every engine is different and some engines make other noises [that are not det] that just happen to occupy the same particular range in the audio spectrum that the det monitor is listening to.

The only accurate way of measuring det is through det cans. You can however get a more accurate real time reading by buying a dedicated det monitor which cost about 200 quid..


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## Pikey (Feb 19, 2004)

Luckham said:


> Not true matey - if your afm's max out the ecu also flashes [but slower] [assuming you still have AFM's that is!]
> Also you can re-set the max reading by going to real time mode and then going back to peak reading..


I didnt know that  

Pretty sure your peak readings arent reset until you turn the ignition off though.


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## turboshed (May 5, 2006)

i thought you press up to go to peak readings, then right to clear them, and then down if you want to go back to looking at your real time readings again.........


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## Luckham (Nov 10, 2005)

Pikey said:


> I didnt know that
> 
> Pretty sure your peak readings arent reset until you turn the ignition off though.


You can definitely re-set the peak reading without turning her off, I think [from memory] is it by going to real time and then peak again, but I'm not near the car right now so I can't check.
I'll check the key combo again when I go back to my place later and let you know


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## markyboy.1967 (Feb 14, 2004)

*Peak*

Yip, you dont have to switch the car off to clear peak readings...


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## leggus (Feb 15, 2006)

Luckham said:


> The only accurate way of measuring det is through det cans.


At 0.9 bar there was no det (using det cans) but not so sure at 1.2 bar.. am gonna leave boost at 0.9 til the map is tweaked.


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## dan0h (Jul 26, 2002)

As Pavlo says, remember that the PFC knock reading is merely a guide, and is subject to hideous inaccuracy which varies from car to car - some rattle away at 20, some see idle readings of 50 or more. A great deal depends upon how tight the knock sensors have been done up.

In short - dont depend upon it to keep you safe, it is merely a microphone in essence and only tells about 25% of the story behind engine noise which may or may not be det.


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## [email protected] (Oct 27, 2005)

any info on the laptop connectoin?

my engines being rebuild and im going for power FC and a non AFM set up but would like to connect to my laptop to monitor things


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## leggus (Feb 15, 2006)

dan0h said:


> the PFC knock reading is merely a guide, and is subject to hideous inaccuracy which varies from car to car - some rattle away at 20, some see idle readings of 50 or more. A great deal depends upon how tight the knock sensors have been done up.
> 
> In short - dont depend upon it to keep you safe, it is merely a microphone in essence and only tells about 25% of the story behind engine noise which may or may not be det.


Driving home tonight in rush hour traffic, didnt get above 2500 rpm, but got a peak of 51!

Yet going out this morning, managed 5000 rpm on the motrway at one stage.. reading max was 29

Think i'm going to turn it off, am forever checking it, and if like Dan0h says, other factors affect the reading its making me paranoid for nothing...:sadwavey:


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## Pavlo (Sep 12, 2002)

if you get the knock showing on the "monitor" of the commander, and press "next" until you see the trace, it can be useful to look at after you've done a pull through a gear. You usually have enough time to accelerate through (say) 3rd gear, then back off and check the trace for spikes in the knock count. You are looking for spikes or a sudden step and sustained high level.

Don't be surprised if you get a small spike from a gearchange, or even from the sound of a dump valve closing depending on how it's mounted.

Paul


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## moNoKnoT (Dec 18, 2004)

Guys,

I've never known a tuner to leave a car knocking!

Do all skylines knock or are people changing their state of tune without remapping the fuel etc correctly? :nervous: 

- Kevin.


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## leggus (Feb 15, 2006)

Now i'm convinced there's something else triggering the knock meter... just went to the chippy, nice bit of dual carriageway on the way... third gear to redline, full throttle nice and smooth, knock 21..

Came out of chippy, turned right at lights at pullaway revs, light flashed, meter reading 100!

Why would it do this??


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## SteveN (Aug 6, 2002)

moNoKnoT said:


> I've never known a tuner to leave a car knocking!


You serious? Id say at least 70% of tuned car failiures can be attributed to det, usually when top ending the car and so on.

Might not det often, or much, but any at any point is too much.


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## moNoKnoT (Dec 18, 2004)

SteveN said:


> You serious? Id say at least 70% of tuned car failiures can be attributed to det, usually when top ending the car and so on.
> 
> Might not det often, or much, but any at any point is too much.


Yes I am

My Type-R was tuned to about 230bhp using K-Pro and I could run data logging on that all day long running from 5,000 - 8,600rpm and i didnt receive a single knock....ever! It runs no way near skyline levels of tune hence its time to move on but it never knocked.

Surely cars knock when their not running correctly, ie crap fuel, bad fueling, poor ignition timing, poor cooling etc etc...

- Kevin.


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## Jim27 (Jul 1, 2004)

leggus said:


> Driving home tonight in rush hour traffic, didnt get above 2500 rpm, but got a peak of 51!
> 
> Yet going out this morning, managed 5000 rpm on the motrway at one stage.. reading max was 29
> 
> Think i'm going to turn it off, am forever checking it, and if like Dan0h says, other factors affect the reading its making me paranoid for nothing...:sadwavey:


Although they usually go hand-in-hand, det isn't *always* at higher rpm. If your fuelling's ok at the top end but the mid-range has a crap map then you're more likely to see knock at lower rpm than higher, I think. I got a knock reading of 110 when applying light throttle whilst cruising at 50 in 5th once. Not sure whether I trust it or not but when I get the old girl remapped I think I'll rob the piggy bank for a set of new knock sensors. The factory ones are 15+ years old now and the PFC is only as good as the sensors it's connected to.


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## EvolutionVI (Sep 6, 2005)

The Knocksensor only monitors engine noise,gearboxnoise,clutchnoise,everything is shown in the "knockmonitor",so its difficult to see whats knock and what is normal noise,if you keep around 30 max under high load,you will be on the safe side. I would look what the monitor does when you are doing gearchanges,if there is a higher "knock",then this is only gearbox/clutch noise:clap:


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## anthonymcgrath (Feb 22, 2005)

I'm quite new to the subject of knocking and the like but I can vouch for this having just had my pfc fitted recently. A friend of mine (whose just got his own gtst and awaiting vosa paperwork etc) took mine up the road with me for a flooring - he got a knock value of 25 on mine but this was the second he went from 4th to 5th which he crunched a little.
I'm quite adept with my clutch/gearing in my own car (driving it every day like all the other owners hehe!) and I only see knock values of 15 maximum. like someone else said earlier every car is different.

I also noticed slightly higher knock levels on lower octane fuel - I had it mapped on Vpower and was barely seeing a knock above 14 ...I recently had to put some tesco 97 in and the knock rose to 17/18
I put some NOS octane booster in with the tank to up the octane and it dropped back down to 13/14 this is with me giving it some serious hoofing throughout the full rev range and gears on both the Vpower and the 97

just my observations on it really - as I said I'm a noob to it but am learning loads with the PFC and everyone else on this site 

ta
ant
toon
uk


(car 33gtst)


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## leggus (Feb 15, 2006)

Jim27 said:


> If your fuelling's ok at the top end but the mid-range has a crap map then you're more likely to see knock at lower rpm than higher


I'm certain the map is good throughout the rev range, the person who mapped it has an excellent reputation and did a cracking job of it on the night.:thumbsup:


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## canman (Jul 7, 2001)

I don't think Dan was suggesting that you shouldn't pay much attention to it, just that sometimes they're not that accurate........ my R34 knock readings seem to be very accurate in relation to the professional knock gear we use when tuning, but I know they're not all that close.

If it was me, I'd just take it back and get it checked properly by the tuner...........it's not a big hassle..........and if you don't and it is knocking then eventually it'll cost you a $hitload more in repair bills ! 

Just my 2 cents.


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## anthonymcgrath (Feb 22, 2005)

The prob with the knock sensor is you get used to seeing a small level then when you get a spike you worry a bit. I took it down the 1058 on my way to work this morning, engine warmed up and nice n dry so I hoofed it. going from 2nd to 3rd I got a knock count of 23 and was worrying even tho my knock level is set to 35 ! I then realised that all I'd done was crunch the gear slightly.

I suppose the handy thing about the pfc is it should definitely detect serious and repeated knocks (values like 60upward maybe) which you'll prob see at regular intervals as your driving. a friend told me that you'll hear and feel it a bit it as much as owt else.

From my personal viewpoint I guess whats happening is i'm starting to micro-manage my knock count and worry too much when what I should really be doing is listening to the engine along with using the pfc. dunno if all that makes sense but I'm just saying as a new pfc user that it can make you sit in the car and worry about sod all hehe!


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## leggus (Feb 15, 2006)

Yes, the worst 'spikes' are when there is clutch/gearbox activity, when its on full tilt the level is generally low (i.e. under 20)


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## dan0h (Jul 26, 2002)

anthonymcgrath said:


> I suppose the handy thing about the pfc is it should definitely detect serious and repeated knocks (values like 60upward maybe) which you'll prob see at regular intervals as your driving. a friend told me that you'll hear and feel it a bit it as much as owt else.


Actually no, I have had PFC cars on the dyno rattling like a paint-tin full of gravel and showing only 20's and 30's. The PFC knock only seems to be a useful guide on a standard engine, any physical mods (cams, pistons, rods) and its basically as good as useless. IMHO.


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## anthonymcgrath (Feb 22, 2005)

I really wish I knew how it sounded without having to rely on yet another dial I have to monitor!! A friend mentioned that it kinda made an increasing "dah.... dah... dah.. dah. dah dah dah" (newwwwww yorrrrrkkkk lol!) sound that got louder under the engine block. anyone have any examples?


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## Hugh Keir (Jul 25, 2001)

anthonymcgrath,

Here you go, download this file and it will let you listen to an engine that has normal ignition timing for the first 12 seconds at the start, with too advanced for 10 seconds and detonating in the middle, back to normal ignition timing for the last eight seconds at the end.

The sounds are as you would hear through a frequency filtered listening device and is not available from the Power FC.

Clicky


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## canman (Jul 7, 2001)

I always say it sounds like someone with a pen tapping on glass...........thats what it sounds like to me.


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## ExScoobyT (Jan 6, 2004)

...small mice with steel clogs sitting on the piston crowns.

First they start tapping their toes.
Then they start dancing.
Finally they get their pneumatic drill out.....

Hugh - no need for frequency filtering, sounds the same through det-cans.


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## anthonymcgrath (Feb 22, 2005)

Hugh Keir said:


> anthonymcgrath,
> 
> Here you go, download this file and it will let you listen to an engine that has normal ignition timing for the first 12 seconds at the start, with too advanced for 10 seconds and detonating in the middle, back to normal ignition timing for the last eight seconds at the end.
> 
> ...


wow thanks that was quite handy - Its obviously filtered as you say but it helps in the sense that you get an idea of the 'speed' of the sound and things like that. thanks alot 

pen tapping on glass and mice with steel clogs... you can distinguish all that amidst the engine fan belts whirring and the injectors clicking away hehehe!


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## Gez (Jan 8, 2003)

I agree with some of the comments above. The knock sensor will pick up all noise. If your engine is on uprated mounts and you have a hardcore tripple plate etc more noice will be produced which in turn will be picked up by the sensor. Just make sure your sensor is clean and is tightened down properly. You may also see higher than normal knock levels on a hard gearchange...

As long as your mapper has taken the car to the edge to see what ign advance it takes etc etc and then maps conservatively then you should be fine.

Regards

GEz


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## Hugh Keir (Jul 25, 2001)

ExScoobyT said:


> ...small mice with steel clogs sitting on the piston crowns.
> 
> First they start tapping their toes.
> Then they start dancing.
> ...


I have listened to det through pipe work clamped to the engine and to unfiltered circuits which are nothing like as clear as a frequency filtered circuit.

The circuit I use picks up almost no engine noise in 0 to 4.5 kHz range or in the 7kHz and above, with maximum output at between 5.5 and 6kHz.

I normally have the output plugged into headphones rather than make recordings and can say for sure that frequency filtering helps me.

I have also compared the output of the Power FC trace, on a laptop, to what I hear through the filtered circuit and know for sure which one I would rather rely on.


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## ExScoobyT (Jan 6, 2004)

No doubt the usefulness of the PFC monitor decreases the further from standard hardware you move.


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## Andy Hornsby (Mar 22, 2003)

Hugh Keir said:


> anthonymcgrath,
> 
> Here you go, download this file and it will let you listen to an engine that has normal ignition timing for the first 12 seconds at the start, with too advanced for 10 seconds and detonating in the middle, back to normal ignition timing for the last eight seconds at the end.
> 
> ...


Very interesting Hugh. 

I had a listen through the head phones on Saturday when I was out with Rod doing the final mapping on mine. Glad to report it was clear all the way. Starting to understand the reasoning behind all this tech stuff.

I'm sure that the right hand button will reset the peak values as you still have the real time display visible.


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## anthonymcgrath (Feb 22, 2005)

is that what Rod uses as he's mapping the car Andy? (along with the laptop etc..)

If so thats pretty cool


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## Andy Hornsby (Mar 22, 2003)

Yes mate. Interesting  and unnerving at the same time. It's weird!


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## DUNCAN GT-R (Nov 6, 2004)

I had mine mapped by Pete at Thor. He said only to worry if it goes above 64 on the knock scale.
When i crank the car it jumps to 3 or 4, and i can honestly say it's never gone above 10.
Maybe thats just good mapping, coz i don't dive like a pussy !!!


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## D4T (Jun 3, 2004)

Hugh Keir said:


> anthonymcgrath,
> 
> Here you go, download this file and it will let you listen to an engine that has normal ignition timing for the first 12 seconds at the start, with too advanced for 10 seconds and detonating in the middle, back to normal ignition timing for the last eight seconds at the end.
> 
> ...


Do you have the unfiltered version? would be interested to see if/how loud the det is heard then


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## anthonymcgrath (Feb 22, 2005)

have to say after listening to that audio file a little more - when my car was at 25degrees (prior to me adjusting it last night) I was hearing a very slight clicking like that from under the bonnet (had to turn everything else off and find a quiet road mind) - the pfc also provided extra evidence with the spikes to match! All this was only whilst on boost mind.

yep would like to hear the unfiltered version myself

after tweaking the ignion a good few times I never see counts about 15 now on hard boost through the gears so quite pleased altho I can make fine adjustments the timing using the pfc (retard by 1degree) and it runs famously


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## D4T (Jun 3, 2004)

See i find that kinda interesting, even when my car is idling i see readings of about 11-12 when warm. Do i assume my knock sensors are a bit old and duff? or do i assume my car is just noisy compared to others? i guess every car is different, as i test i pulled all the timing right back the knock reading was still about 25-30 on low boost at about 6000rpm so i am taking it that that is safe for my car for now


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## D4T (Jun 3, 2004)

Ok wierd, today intermittantly the knock levels dropped considerably.... i assume i have something odd going on just not sure what!


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## leggus (Feb 15, 2006)

PowerFC knock levels ive decided are subject to all noises not just det noise..

After driving to Shakespeare today, and gettin a spike of 65 going over a drain cover at 40 mph 2000 rpm, then launching the car at redline and flatting the throttle out in every gear to nearly limiter...., max knock 22!


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## D4T (Jun 3, 2004)

No see thats the thing, it was reading 10-12 on idle (in my quiet close) then all over a sudden after a good gunning was reading 1-2 on idle. wierd! :O loose knock sensor maybe?


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## anthonymcgrath (Feb 22, 2005)

D4T ...I dont know if you've noticed this but I'll see very low knock levels (single digits) when I start the car and head to work. ten minutes in the car has warmed up and I'll see the knock level climb a little sometimes as high as 17 or 18 ..however I've also noticed that this is when the cars water temp has reached aroudn 70degrees so I'm guessing its something related to the car making adjustments for a warm idle or maybe an oil cooler switching on (dont even know if my gtst has an oil cooler hehe!)

hope that makes sense. I've also noticed that knock spikes occur if the car is too retarded as well as too advanced - maybe this is just sheer engine vibration or something as the car kind of battles its way past the 'wall' a retarded ignition creates (hard to describe but you know what I mean I think!) when you floor the gas.
like other have said on this forum it is kind of hard to use the knock reading as a sensitive gauge as its unfiltered and picks up noise from all kinds of other sources (crap gear changes, bumps in road etc..) but I guess so long as your not getting massive repeated spikes of 60+ when accelerating hard your ok 

just a couple of thoughts on it ...been tinkering alot with it lately and seem to be noticing patterns with it now


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## kismetcapitan (Nov 25, 2005)

how do I reset my knock threshold - I want to lower mine from 60 down to a more fastidious/paranoid level


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## Hugh Keir (Jul 25, 2001)

D4T said:


> Do you have the unfiltered version? would be interested to see if/how loud the det is heard then


D4T,

I never bothered with an unfiltered version as that kinda defeats the purpose of what I was tying to achieve.


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## SiKBoY (May 15, 2006)

Thread revival, been looking for info like this for a few days.

Mine registers 91 on Startup which I clear straight away, I think I am going to go on 1 channel mode realtime to trace the graph.


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## kismetcapitan (Nov 25, 2005)

I watch knock on the graph, otherwise that damned bar flickering up and down will have me dead from paranoia within days. I don't have a water temp gauge so sometimes I watch knock and water temp on the graph trace (water temp doesn't exactly jump around )

I've reset my knock threshold to 35, and I've been getting 20-25 on boost today - knock numbers seem higher if I'm not completely WOT. One question though, which I'll post to the Datalogit guys: in Datalogit, when setting the knock warning threshold, what's that number below the threshold number do? it was at 9 and I reset it to 15, not knowing what it does.


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