Odd Knock Reading Powerfc Rb25Det

[menthol369]

ive been lurking on this site for some time now but ice finally run into an un answered question.

I have a s2 25det with stock turbo internals etc. only mods are power fc, front mount, 3inch exhaust boost tee set at 11 psi

so me and a mate did the tuning ourselves. didnt really touch timing. just set the afrs to 12

it ran great with no knock till it went to the track and possiblely leaned out due to a hose coming off the intake from a failed hose clamp non pressure side.

few days after it started to show alot of knock on full load. no matyer where timing was set or the boost that was run. even on idle anf low load itl bump the knock reading up every now and then.

130 psi across all 6 btw

[89CAL]

What knock reading are you defining as alot of knock would be a good start?

Maybe you didn't fix the problem with the boost line. Or perhaps it was slightly leaking before and now its not leaking at all and your AFR's have changed slightly. Do you have a permanent AFR sensor (wideband) setup installed?

If you didn't touch the timing at all I would suggest you do. It shouldnt be the same as the base map, either to get max results or a safe tune

[menthol369]

atm I just want it to be safe.

it was the bov return to the inlet that slipped. ive fixed it now.

afrs have been checked at 12 recently.

ive checked cam timing and base ign timing is set correctly for the power fc.

and with the knock, as I only have the hand controller to see what it reads its getting to 3/4 at 3k then sorta bounces around from there as the revs increase.

ie 3k will have lots of knock. itl drop down to a quater then go back up at 4 etc etc

[menthol369]

just went and had a fiddle with the timing, there was a guide to see if the knock snesors were picking up other noises.

set timing to 0 deg on full load from 4500-6500. i did this and had pretty well no knock. bumped up to 15 deg and was getting minimal knock.

[boostn0199]

Change the knock to the number vaule itll be easier to define how bad the knock level is.

[89CAL]

This ^

using the bar graph alot of the time is useless. Press up on the hand controller to bring up peak values. Think its the up button anyway

how did you set the timing to 0 degrees under load? The thing would have struggled to move.....

[menthol369]

yeah when it hit the 0 deg it didnt make any power. I just wanted to see if there was other noise.

ill get the peak values next drive

[SargeRX8]

I hit 125 knock the other day full load 4500rpm. I wont induce knock. Ill get it fixed properly. I suggest you do too. Inducing knock is never suggested.

[menthol369]

so i got some values, 147 at full noise.

i played with the timing, from 2200 rpm ive had to set the timing to 15-12 deg. this gave me a max reading of 60 knock.

the only thing that concerns me with that little timing is EGTs

[SargeRX8]

Have you tried going a little richer?

[Badgaz]

just remember that a bad batch of fuel can give you bad knock.....if its constant...worry...try putting some fresh high octane in it...

[Dose Pipe Sutututu]

the stock PowerFC ignition map actually runs quite a lot of timing, do a trace and see what row it hits and shave off about 2~3 degrees for that row and 1~2 from the above row and below row

[n0nac]

the stock PowerFC ignition map actually runs quite a lot of timing, do a trace and see what row it hits and shave off about 2~3 degrees for that row and 1~2 from the above row and below row

totally agree.

if your afrs are 12 on full boost... you have to reduce timing.

knocks of 120 is deffo not good what so ever.

if it were me, id knock 4 degrees of timing out of hte map and diagnose.

if its knocking its tits off on full boost WOT above 3000 rpm, you know where abouts it will be in the map by looking at the tracer function of your hand controller and set it to Map trace to record where hte map runs.

if its still knocking, remove more timing..

then once its stopped knocking stupid amounts, start to add in more timing, to bring your powr levels back up.

you should be tuning this with a wide band also, to make sure your afrs are all good.

food for thought.

my SR20 runs 9 degrees timing on full boost mid-high end of rev / load range. on 16psi boost.

11.5-12 afrs and knock peaks at 18 usually.

my mates r33 skyline, was running 12psi. reasonably rich afr's and it started knocking its absolute tits off. +120.

found that that the nipple in the hot pipe for hte boost control was just screwed in... it came loose. and caused it to knock its tits off.

fixed it properly, and knock settled down to about a max of 30 off memory. it was many years ago that happened now.

Edited August 23, 2013 by n0nac