A Must Read For Budding Tuners, Or Those Interested In "knock"

[Drift Motorsport]

Check the knock sensor loom for any splits / continuity and so forth and make sure that it is getting a proper signal from the knock sensor.

[battery]

use temp IGN adjust to back out -8 deg timing and floor it

if its does the same you can be pretty sure its not ignition related knock and some form of mechanical noise etc

yeh i have tried this its better but still manages to hit 70 very easy...

[STATUS]

hey trent i have this "false knock" issue im trying to sort out perhaps you have some ideas...

i have a rb25 with a power FC making 200kw, basically i get crazy knock readings and i'd really like to fix it so i can have a go at tuning the car.

on startup it will read 20-40 and i can be driving along in any gear around 3000-4000rpm not much load and it will shoot up to 80-100. On WOT it can hit 200.

I have had 2 different tuners check the car out and they reckon its fine, its been in this state of tune for over 20000ks with no issues.

I have a 5 puk exceedy clutch, oil cooler and relocation kit, other than than that its pretty standard. I have tried changed the knock sensors but there was no change.

whats the best way to eliminate this problem??

Some PFC's have this issue we come across it every so often, its generally a knock sensor issue or a loom issue...

One of the reasons we like to use secondary knock detection when tuning.

[DVS JEZ]

how long does it take to setup a kmon or similar for the 1st time? do you have to set it up for each engine and car?

[STATUS]

how long does it take to setup a kmon or similar for the 1st time? do you have to set it up for each engine and car?

2mins max, on big setups maybe 5mins as i prefer to get to a better spot on the block instead of the head.

[Smegul]

Ive got an rb30 turbo with a really quiet exhaust. The car seems to drive perfectly, run really smoothly. Are you saying It could just pre ignite at any time or be detonating and i wouldnt even hear it? I thought pre ignition sounded like a marble or something in your cylinder, like a really pronounced bang?

Also what is the optimal spark plug to run in it. Its a standard N/a motor, high comp, n/a cam etc, with vlt injectors, vlt computer, stock manifold turbo etc. Will be installing water injection soon and trying to push it to 14psi. From what ive read if i get the water right i can lean it out a bit even on the n/a high comp motor. Only problem with doing that is if the water fails then almost certainly your motor will too. Its been going for 2000km and the sparkplugs have no signs of wear, this is a good sign of no detonation right?

And in your opinion how much longer (i,e a few seconds?) can forgies handle pre ignition for versus cast pistons?

Kind regards,

Jason.

[Rolls]

Bad detonation sounds like marbles but by then it is too late, you can still get detonation that you won't hear unless you've got your head in the engine bay.

Pre ignition is a different thing that can destroy a piston with just one event. It is where it ignites on the compression stroke, basically trys to compress an explosion. Detonation is where after the spark ignites the fuel the shock wave causes some of the mixture to explode instead of burn, so there are different stages, can have a very small amount of the mixture explode or almost all of it.

Pre ignition will destroy any setup, detonation will be better tolerated by forged pistons but as its such a variable thing there is no way to say how long it'll last, avoid it at all costs.

Edited January 29, 2011 by Rolls

[VB-]

Ive got an rb30 turbo with a really quiet exhaust. The car seems to drive perfectly, run really smoothly. Are you saying It could just pre ignite at any time or be detonating and i wouldnt even hear it? I thought pre ignition sounded like a marble or something in your cylinder, like a really pronounced bang?

Also what is the optimal spark plug to run in it. Its a standard N/a motor, high comp, n/a cam etc, with vlt injectors, vlt computer, stock manifold turbo etc. Will be installing water injection soon and trying to push it to 14psi. From what ive read if i get the water right i can lean it out a bit even on the n/a high comp motor. Only problem with doing that is if the water fails then almost certainly your motor will too. Its been going for 2000km and the sparkplugs have no signs of wear, this is a good sign of no detonation right?

And in your opinion how much longer (i,e a few seconds?) can forgies handle pre ignition for versus cast pistons?

Kind regards,

Jason.

detonation is very distinct if you know what it sounds like. i'd never heard it until it was pointed out to me one day, and now i pick it up all the time, even just on normal cars driving in traffic that *should* be run on a decent fuel but are only getting fed 91oct.

spark plugs generally wont cop any damage from detonation, but will show some black specs, or even silver ones, around the porcelain.

hard to put a time constraint on how long each piston would last for. i've been caning a mates soarer recently while chasing what i thought was ignition braking down, which was actually a massive lean condition, despite being told by a dyno operator that it was flat at 11.5:1 (issue currently being rectified with help from trent), and its been copping it hard, and for a long time lol. still going strong though, standard cast pistons

instead of spending your money on water injection, get some GTR injectors and a nistune. cost a little more but the result will be about 487 times better

[STATUS]

detonation is very distinct if you know what it sounds like. i'd never heard it until it was pointed out to me one day, and now i pick it up all the time, even just on normal cars driving in traffic that *should* be run on a decent fuel but are only getting fed 91oct.

spark plugs generally wont cop any damage from detonation, but will show some black specs, or even silver ones, around the porcelain.

hard to put a time constraint on how long each piston would last for. i've been caning a mates soarer recently while chasing what i thought was ignition braking down, which was actually a massive lean condition, despite being told by a dyno operator that it was flat at 11.5:1 (issue currently being rectified with help from trent), and its been copping it hard, and for a long time lol. still going strong though, standard cast pistons

instead of spending your money on water injection, get some GTR injectors and a nistune. cost a little more but the result will be about 487 times better

haha those gas love that 11.5AFR dont they.... shit it was more like 16 to 1.... was lucky we checked their work.

[DVS JEZ]

leaning out an engine can be tolerated for a lot longer, especially if its waaay too lean. as long as it doesnt create hot spots such as glowing spark plugs that cause preignition

[MJTru]

This is my 2 cents, You tube has a good vid of this, check it out.

http://www.youtube.com/watch?v=Mzf_n9EM-p0&feature=related

[Drift Motorsport]

Engine Vids with knock sound on Youtube:

http://www.youtube.com/watch?v=Due7mkTHMlw&feature=related

Kabbom:

[Galois]

Thanks trent, was a great read!

[MJTru]

Engine Vids with knock sound on Youtube:

http://www.youtube.c...feature=related

Kabbom:

That was in the back the motor is in the front, so i dont think that this is det. lol.

The first vid was good the sound that det makes mate.

[swarzee]

wow, i have learned alot from this post.. Many thanks to every1 involved for sharing their knowledge.

[SiR_RB]

wheres a good spot to mount a knock sensor on an rb26 during tuning?

[DVS JEZ]

Rb 26 is impossible to mount onto the block. So have to mount to the engine head preferably near a coolant passage as the knock will travel through the water better than air.

Yavuz prefers to use his trained ears to listen for knock

[Checkbuzz]

That is a mind blowing read !

Sticky?

[O2 Autosports]

Yavuz prefers to use his trained ears to listen for knock

Your kidding right?

[DVS JEZ]

Nope. And that proves it works fine.

He has a extremely good reputation.

The drag car he sponsors is tuned at the track using egt sensors and transducers in the spark plug to monitor cylinder pressures.