High Knock Reading

[paulr33]

It is recommended to write down your IGN map before you begin.

You can do this by going to SETTING, IGN MAP and writing down the values

into an excel spreadsheet. If you make a mistake or change the values too much you can simply revert them back by inputting the numbers again.

Quick and Easy Way

1) get a friend

2) drive around, get engine to normal temp

3) disable all engine flash light modes except for knock

4) MONITOR, 4 CHANNEL, KNOCK, ENGINE RPM, AIRFLOW, IGN TIMING

5) get the driver to try an replicate the knock

this is likely to be on max/full load so do it somewhere sensible.

now that you have confirmed you can replicate the knock you can try a quick IGN temp adjust.

6) SETTING, IGN/INJ ADJUST

7) press DOWN 3 times

8) the IGN value will show -3

9) get the driver to try an replicate the knock

it is likely at this stage you wont see any more knock. if this is the case;

10) SETTING, IGN/INJ ADJUST

11) press UP 3 times

12) the IGN value will show 0

13) read below on how to correct it

Fixing it on the map

1) get a friend

2) drive around, get engine to normal temp

3) disable all engine flash light modes except for knock

4) MONITOR, 4 CHANNEL, KNOCK, ENGINE RPM, AIRFLOW, IGN TIMING

5) get the driver to try an replicate the knock

this is likely to be on max/full load so do it somewhere sensible.

6) when you see the knock go past 60 (or the high level you normally see) and/or the engine check light comes on you need to note down

ENGINE RPM

AIRFLOW

IGN TIMING

7) once you know these values you need to jump to the IGN map and take out some timing. you can either get your friend who is watching the hand controller to note the values down or you can use map tracer. repeat #6 with map tracer running and get the person to note which cell is highlighted when you see the engine check light. basically get them to hold up the hand controller and face it towards the engine check light area and make them watch the map trace and watch for yellow flash.

7a) once you have worked out what cell is causing the engine check light you need to take out some timing

8) SETTING, IGN MAP

9) move to the cell that was visible when you swa the engine check light come on.

10). press NEXT and note the RPM and LOAD value. they should be about on par with what the car was doing at the time when it occured. ie: if revs is 1100RPM then you are likely to be at the wrong cell. THe load values are based off the AIRFLOW load table and not VOLTAGE. the stock r33 airflow table only lets the powerfc user points 1 to 14-15 so it wont drop the to bottom. so max load is likely to be rows 14 & 15

11). once you have the right cell point on the screen press NEXT

12). press down twice and the IGN timing value will be 2 degrees less

13). press NEXT to save the change

14). try to replicate the knock again and watch what cell it occurs on

15). repeat steps 7a to 13 a few times and youll basically smoothen out the map and take out the knocking cells

it may take a few shots to get this right but it should sort out any knocking cells.

[ferni]

From what I know the most common source of knock is

- Too lean (not enough fuel) (also too much boost same catagory)

- Too much timing

- Too much heat causing pre-ignition (similar to crap fuel)

These 3 things is what I'd be looking at - all have been suggested already. Heat is easy to rule out if it does it when its not hot (80-90 water temp) then its not heat...

Timing and fuel you can take out temporarily across the whole range to test.

[R31 POWER]

So getting a knock reading over 100 means a faulty knock sensor/s?

Edited April 22, 2006 by R31 POWER

[R31Nismoid]

rarely...

[SKY 34]

Paul,

what if the knock does not appear at a consistant rpm? sometimes it happens, sometimes not...

I have knocking problem as well...pfc....highest is 95...I think...it's not consistent tho..unfortunately I dun have the cash to re-tune atm...so I'm always using octane boost...hoping mite help...

but soon be not viable..petrol prices driving me mad these days...

[R31Nismoid]

what if the knock does not appear at a consistant rpm? sometimes it happens, sometimes not...

Bad ignition value in on the map is generally the cause.

Which is brought on by one of many things

Temp, fuel, throttle possie, when your planting your foot. Like hooling on the threshold and then planting it.

Many things can cause it.

If you note the RPM, gear, speed, throttle possie anbd rough outside temp

Any tuner should be able to sus that out in a few minutes

[paulr33]

ash is spot on. if you arent confident yourself or dont wanna fidle just note what rpm/load it occurs and the tuner can sort it out.

SKY34: why are you adding octane booster?

[r33_racer]

Also if your engine has been rebuilt on the sloppy side, knock can easily present no matter what amount of fuel or timing is in the map. Engine rebuilds need to be tight to eliminate the possibility of knocking from loose clearances.

We currently have an rb25 with that problem.

Edited April 23, 2006 by r33_racer

[rob82]

Paul,

what if the knock does not appear at a consistant rpm? sometimes it happens, sometimes not...

I have knocking problem as well...pfc....highest is 95...I think...it's not consistent tho..unfortunately I dun have the cash to re-tune atm...so I'm always using octane boost...hoping mite help...

but soon be not viable..petrol prices driving me mad these days...

Are you sure your mixtures are ok. That sounds more like a dying fuel pump giving you a lean condition causing detonation.

[SKY 34]

ash is spot on. if you arent confident yourself or dont wanna fidle just note what rpm/load it occurs and the tuner can sort it out.

SKY34: why are you adding octane booster?

lol...no idea...because it says on the bottle that the bottle will reduce knock... ><

oks.. I'll go for a re-tune...

[SKY 34]

Are you sure your mixtures are ok. That sounds more like a dying fuel pump giving you a lean condition causing detonation.

I got one of those bottles which threat 30-60l of petrol and clean the injector at the same time...lol...umm I'm quite sure it is sumthing to do with the pfc....before I install the unit the car is good....

actually now that you mentioned it...fuel pumps might also be possible, my car often just died halfway driving...jsut switch off like that without stalling....sine it does not happened to ferquently I linked that to improper pfc tune...

I'll go check out the pump as well...

thanks~~

[Fangz]

this could b bad!

tonight my knock reading was 139

power fc (base tune)

4th gear

water temp 80 deg

rpm 4500

injector duty 98.3%

speed 141kmh

timming 44 deg

any ideas?

[MattSR]

If your injectors are at 98% that means you are at full load - 44 degrees at full load will blow your motor up in no time...

If you are on the base tune, then get it tuned ASAP. Full load timing should be about half of what you are seeing.

Edited May 5, 2006 by MattSR

[MattSR]

With a knock reading of 139 you would have been able to hear the knock from inside the cabin...

[Damo]

this could b bad!

tonight my knock reading was 139

power fc (base tune)

4th gear

water temp 80 deg

rpm 4500

injector duty 98.3%

speed 141kmh

timming 44 deg

any ideas?

I think u might be looking at max values here. there is no way the base tune is 44deg at 4500rpm. Its usually this at idle under no load.

Why are u driving it that hard on the base map anyway? Do u not like your engine?

[Busky2k]

Its simple. If you pull 5 degrees out and it still shows knock, your sensor might be shagged. If it doesnt, then its in good working order.

5 deg is alot of timing and should fix any knocking in most motors.

[croat]

When i had a hand controller in i read high knock levels, the dash light also comes on. i have had knock over 100. i have been to reputable tuners who used stethescope's and other knock sensors. i think if knock hit 100 or more you would probably hear it? by the way where is the knock sensor? can you buy HKS or aftermarket knock sensors??

[Hulk1010]

i'm not taking my car back to the previous tuner, i'm gonna go somewhere else in a couple weeks or so, i heard of racepace and another place called croydon( can't remember the rest of the name), any recomendations which one out of the two?

thanks

[Fangz]

I think u might be looking at max values here. there is no way the base tune is 44deg at 4500rpm. Its usually this at idle under no load.

i think it was max values, these were the readings i got when i looked at the controller when i got home.

i wanna get it tunned, but i gotta fit up my (buying bit by bit)

greddy inlet plenum, 3'' dump, hks 740cc inj, fuel pump, q45 t/b, q45 afm and make up some new 3'' cooler pipping and hks cam gears and timming belt b4 i get it tunned

[cameron]

Faulty knock sensor's in GTR's is common apparently, croydon racing can confirm this.

139knock ouch! although you'll proberly find majority of the time its on in 1 or 2 specific load points, if it was getting that level through all the rev range thats bad bad new...