Pfc Knock Values

[paulr33]

spot on, everyone asks whats the difference, im not sure there isnt one

when you are on road tuning and knock fixing dont have the hand controller plugged in

as the bandwidth to the controller port is shared so they end up fighting for updates

which sometimes means the hand controller may see a knock of say 110 and datalogit only see's 75

this is due to the way it sends updates per cycle and they share the bus

basic knock is fine

[Fry_33]

when you are on road tuning and knock fixing dont have the hand controller plugged in

as the bandwidth to the controller port is shared so they end up fighting for updates

which sometimes means the hand controller may see a knock of say 110 and datalogit only see's 75

this is due to the way it sends updates per cycle and they share the bus

basic knock is fine

Thanks Paul, will have to remember that when I get to that stage.

[khunjeng]

cant agree more with Paul.

get the tune going on the dyno, then wack in Datalogit or whatever and go for a road tune...I do this a bit to get the few cells causing the issue ironed out....ur tuner should be able to do it easy...

[Fry_33]

I've had my car tuned on the dyno and got 180.7kW. I had been thinking about road tuning using FC-Datalogit. I created a spreadsheet of my IGN and INJ values and saw how much more advanced Pauls was than mine and how much more power he was making. I went straight out and bought the FC-Datalogit. My current tune looks seems to be the usual and has altered values in the mid to high range but not much, if at all, down low. I's love to pick up some power off boost.

I first want to sort out my noisy timing belt, install my electronic boost controller (EVCIII) as my manual bleed valve lets the boost drop off high in the rev range (should control it down lower a bit better too).

Once that's out of the way I will try to get a get the AFR's right and then start dialing in some ignition. Hopefully it will let me do this and pick up a bit of power. I have a fiarly quiet exhuast (HKS Super Dragger) which is probably holding me back a bit but I never have any problems with unwanted attention which I like.

[STATUS]

I've had my car tuned on the dyno and got 180.7kW. I had been thinking about road tuning using FC-Datalogit. I created a spreadsheet of my IGN and INJ values and saw how much more advanced Pauls was than mine and how much more power he was making. I went straight out and bought the FC-Datalogit. My current tune looks seems to be the usual and has altered values in the mid to high range but not much, if at all, down low. I's love to pick up some power off boost.

I first want to sort out my noisy timing belt, install my electronic boost controller (EVCIII) as my manual bleed valve lets the boost drop off high in the rev range (should control it down lower a bit better too).

Once that's out of the way I will try to get a get the AFR's right and then start dialing in some ignition. Hopefully it will let me do this and pick up a bit of power. I have a fiarly quiet exhuast (HKS Super Dragger) which is probably holding me back a bit but I never have any problems with unwanted attention which I like.

BEFORE YOU DO ANYTHING SET YOUR BASE TIMING... as this could simply explain the differrence in timing up top.

[Fry_33]

BEFORE YOU DO ANYTHING SET YOUR BASE TIMING... as this could simply explain the differrence in timing up top.

It's ok URAS, I should have explained myself fully. I have already checked the base timing and it's on 14-15deg BTDC.

I compared my IGN values to Pual but also to the standard IGN values. When compared to the standard IGN values I can see that only the mid to high values have been altered.

Just a question, Does it matter that the for the standard ECU the base timing is 15deg BTDC @ 750rpm (maybe 650rpm, can't remember off the top of my head) and the with PFC idles at about 900rpm. Should the base timing be set differently because it's a different rpm or should it be set to 15deg BTDC and then just tune the car around that?

[Beer Baron]

are you really setting the timing, you are you just looking at what the PFC displays? you need to get your head under the bonnet mate and check the base timing with a timing light. check those figures too in the workshop manual, don't trust the compliance service sticker. GTR stickers all say 15BTDC too but they are actually 20BTDC... I don't know 25 figures off the top of my head, but check it anyway.

[The Mafia]

no, you can't do it that way.

You NEED the datalogit, and you need to go for a drive and see what cell is causing the knock.

There are 400 cells on the Powerfc, and the handcontroller only shows the highest reading of all of the knocked cells. So adjusting the cas is just stupid, and so is just blindly adjusting cells in the powerfc.

You need to use mapwatch.

I can get a reading of 100+ on the HC and look at map watch and see that only one single cell out of the whole 400 is doing this. All of the other cells that aren't knocking at all and showing 0 probably need timing advanced the shit out of them.

Thats what I did, and all cells now have a minimum of about 3 knock

[Fry_33]

Beer Baron,

I checked the timing using a timing light, I'm not a complete tard

The timing figure seen using the timing light matches up to what the HC displays.

The base timing is as follows.

My car just won't idle with the PFC below 850-900, I haven't played with the idle screw though.

Jono,

I am not adjusting the cas at all. the base timing is correct so that's where it will stay. I was just wondering whether the above base timing figures would alter as my car idles at a higher rpm than what is stated (650 +/-50rpm).

I quickly did a mapwatch on knock the other night when it finally played ball and initialised with the laptop. I was just sitting in the garage at idle and revved it lightly a few times and the average knock was about 3-4 in some of the cells from memory. Once I get a few other things sorted then I will start to alter things.

[Dale FZ1]

Have you cleaned/adjusted the IAC?

I would suggest doing it, regardless of whether the thing idles perfectly with the standard ECU in place.

Remember your idle is governed by both the ECU settings and engine hardware.

[TTOBES]

You can get quite high peak cylinder pressures if your motor is idling too slow.

At higher revs, in the time taken for the mixture to burn, the piston moves down the bore increasing the chamber volume for the expanding gasses to fill. This lowers the peak pressure.

At idle the piston does not move significantly in the time taken for the mixture to burn so, even though there is not a huge air/fuel charge in the cylinder, it has a much smaller volume to burn in and the peak pressure can be significant.

This may be why the knock values dropped somewhat when you increased the idle.

Food for thought...

[The Mafia]

You can get quite high peak cylinder pressures if your motor is idling too slow.

At higher revs, in the time taken for the mixture to burn, the piston moves down the bore increasing the chamber volume for the expanding gasses to fill. This lowers the peak pressure.

At idle the piston does not move significantly in the time taken for the mixture to burn so, even though there is not a huge air/fuel charge in the cylinder, it has a much smaller volume to burn in and the peak pressure can be significant.

This may be why the knock values dropped somewhat when you increased the idle.

Food for thought...

I like this reply, nice theory. I think it could be correct too.

[STATUS]

no, you can't do it that way.

You NEED the datalogit, and you need to go for a drive and see what cell is causing the knock.

There are 400 cells on the Powerfc, and the handcontroller only shows the highest reading of all of the knocked cells. So adjusting the cas is just stupid, and so is just blindly adjusting cells in the powerfc.

You need to use mapwatch.

I can get a reading of 100+ on the HC and look at map watch and see that only one single cell out of the whole 400 is doing this. All of the other cells that aren't knocking at all and showing 0 probably need timing advanced the shit out of them.

Thats what I did, and all cells now have a minimum of about 3 knock

Dont tune by the knock value though it is not accurate you should be using some type of listening device like a K-mon/knock box etc see link. http://www.skylinesaustralia.com/forums/t1...l&hl=gizzmo

[The Mafia]

I know, but I just listen for knock in the higer loads. The Knock sensors on the RB25 are pretty bloddy good though.

But also, a lot of people can't afford those $1k+ gadgets you use for listening to knock, and plus a lot require you to be in the dyno..

I just go by -

Full load - around 20, give or take 5

Low load, 5 or below

Remember, those figures aren't "knock" they are just a threshold. I've noticed anything over 40\50 is audible knock.

[STATUS]

exactly right about "threshhold"... on some cars there can be as much as 20rwkw hiding in that threshold that can only be realised with decent listening equipment.

[The Outsider]

In my experience i've found the thing that makes the car knock (<10) on start up, is the car's recent driving habits. If i've only been puttering around for a couple of days or the car's been idling a fair bit, on a cold start-up it'll have a go at knocking, and also the first time i sink the boot and make some solid boost it'll knock slightly (<20), and sometimes light smoke. But it's right after that without any more knock seen.

The other thing you need to consider is the knock detection method. A knock sensor is really just a flash-as microphone. And sound is only vibration. The classic is the bloke with a screamer pipe off his wastegate that exits near the sensor, and causes enough vibrations that the engine thinks it's pinging off it's tree every time he hits full boost.

I suffer mildly from a similar type of problem due to my "custom"-spec exhaust. I've had the car tuned and it's just an inherent thing on my set-up.

Also, I find I don't so much hear knock as feel it. I find if the car isn't pulling like it should when I give it the giggle berrys, it's cos it was knocking. Still, a decent tune has resolved most of my problems. A turbo with a tiny exhaust housing is still an issue but..... come on pay day(s)!!

[mickr33]

I am concerned with my knock readings. Expecially on cold mornings i see up to 130 sometimes, though having said that i never hear any pinging and the engine light does not even flicker. Even other times under the same conditions the knock reading is much less like around the 50 mark? I am really confused and a bit worried. Should i be getting it looked at although i cant hear any pinging what so ever?

[dezz]

I am concerned with my knock readings. Expecially on cold mornings i see up to 130 sometimes, though having said that i never hear any pinging and the engine light does not even flicker. Even other times under the same conditions the knock reading is much less like around the 50 mark? I am really confused and a bit worried. Should i be getting it looked at although i cant hear any pinging what so ever?

whether its actually knocking or not, if the value is reading 130, then the light should be flashing at that time, unless a) your check engine globe is blown, or the warning is turned off in the pfc, or set to a ridiculously high number

[skylinekid]

after my hours of pointless driving getting to know my car i regularly had knock values as high as 90 but only in certain situations.... plus u could get a bad dose of petrol and ur knock value would increase. i find i could consistently make it knock if i sat in 5th on the highway at about 100 and having a fairly big turbo it would lag until about 130 but from 100 to 130 it would knock on and off from 15 to 90 only a test i dont do it regularly.

but as for knock at idle thats a lil odd maby u have a lil bit of valvetrain noise coming through sumwhere could be nethin.... as even sumthing like a lil rock hitting the sump can cause a knock reading to go ballistic...

[mickr33]

whether its actually knocking or not, if the value is reading 130, then the light should be flashing at that time, unless a) your check engine globe is blown, or the warning is turned off in the pfc, or set to a ridiculously high number

Thank's Dezz. If it was the case of a blown globe or the warning turned off or set to high shouldnt i still hear the thing ping it's head off? Also is it easy to check the warning and setting on the H/C.