Hi all. Having installed my PFC and Commander a week ago or so now and with it running fine on my setup for now until I get it properly mapped. I have been monitoring all readout values. I understand all of them but don\'t really get what knock is.
What is knock supposed to represent?
On the PFC it is displayed in real time mode as a bar graph, but I have also been monitoring the value as a peak hold value which gives it in number form.
On average I am getting around the 30 mark over run. With the odd spikes to numbers such as 48, 52, 60 and had a high one (I think) of 79, when giving the car some stick coming off of the M1 down a slip-road. When this occured I think I could literally hear the "knock". Not sure.
Just wondering if you guys can explain knock. And what values are good, bad, etc. And at what sort of values (generally) does damage occur and in what form? What knock should I be aiming for? And what affects the value?
In case you need it to answer for my set-up in particular at present. I have the following set-up on my UK spec FD.
Standard twin turbo engine.
Downpipe.
Cat-back exhaust.
Induction filter box.
HKS ignition amplifier.
Magnecor leads.
NGK 9 -trailing, 7 - leading plugs.
Apexi PFC + Commander (base map)
Greddy turbo-timer.
Pettit Racing AST with race cap.
Race oil cap.
Thanks.
No-one?
Knock must be a mystical, unexplainable numerical value. Imao.
I don\'t understand the terminology behind \'knock\', but I\'m pretty certain high knock numbers aren\'t too clever!
Alot of Impreza owners have knock level sensors.
A knock sensor is simply a microphone, tuned to \'listen\' for knocking in the engine. The number is a level of noise that sounds like knock that the sensor is picking up. Therefore, the higher the number, the more noise it\'s picking up. The problem is with the sensor, is that it can pick up noise from other areas, so when you get high numbers which would normally indicate a knocking engine that would cause engine failure, it may actually be noise from other areas within the engine bay.
Hope that helps.
knock is when you get two flame fronts that collide within the combustion chamber giving a loud knocking noise and quite possibly doing serious damage to the engine. Thats how I understand it anyway. Apparently it\'s very difficult to hear in a rotary, apparently the engine will fail before any really clear \'knocking\' noises are made :3Confused
No idea what the numeric value is and I guess it\'s just that ... a number and the people at Apexi have learnt imperically what is too high.
I often seen 200+ on my knock readout but the engine is still goin:confused:
In saying that i was told the big singles knock for no reason what so ever...
Also, a knackered sensor can sometimes give false high readings. Provided your car has been mapped and you\'re using the same type of fuel as per mapping (i.e v-power/SUL) then there shouldn\'t be a problem.
OK... some good answers there.
But what magnitude figures have you guys been getting on your individual set-ups according to the read-outs on your Apexi Commander for knock?
What are your engine set-ups in terms of parts, spec, etc?
What figures have you been getting read-outs for on average and odd ones?
When do you see the highest figures and when the lowest figures?
this suonds a bit bizarre to me as mine is always 1.
if you press up on your commander it gives you peak readings that you had before you shut the engine off since you turned it on.
mine always reads 1 as the highest.
isnt this meant to hear detonation. and is it located in the exhaust as i have removed my cat so taken the prong out of it etc, but i thought it was in the downpipe.
1!! I would say you have a faulty sensor or something. I tend to get between 15-40 most of the time. Every now and then I do get a high reading but as mentioned previously I believe it has just picked up some noise from somewhere else. It has just been mapped and I always use V Power so i\'m not worried about intermittent high values
However, if you were constantly getting high values I would be concerned and my first step would be to contact one of the specialists and get booked in for a mapping session (or at least some advice)
knock in effect is detenation
the figure that i was told buy pip was 60. anything over this then you should be worried (i guess on a regular basis).
bizzarily pip showed me all the knock values on the dyno spark/rpm chart? from one of my runs and there was only about a dozen sites that had any knock (highest being 8) however every single journey i make i always get a higher figure than that.
sometimes 14ish sometimes up to about 45.
knock sensors are normally just attached to the block, so as said before if a largish stone from the motor way flicked up and hit the block, therefore making a readable sound by the knock sensor, it would/could give you a much higher reading.
p.s M4drx- i am pretty sure there must be a problem with your sensor
Quote from: D1 WTFknock in effect is detenation
the figure that i was told buy pip was 60. anything over this then you should be worried (i guess on a regular basis).
bizzarily pip showed me all the knock values on the dyno spark/rpm chart? from one of my runs and there was only about a dozen sites that had any knock (highest being 8) however every single journey i make i always get a higher figure than that.
sometimes 14ish sometimes up to about 45.
knock sensors are normally just attached to the block, so as said before if a largish stone from the motor way flicked up and hit the block, therefore making a readable sound by the knock sensor, it would/could give you a much higher reading.
p.s M4drx- i am pretty sure there must be a problem with your sensor
oh w4nk i need to sort this before the 19th bcos im using this as a check inacse im running lean. this needs to be right!
can anyone tell me where and how much?
i will create a new thread but it seems as though its not connected doesnt it?