Knock Level Increase...hmmm

[NSNPWR]

Go throw some octane booster in it and a fresh tank of 98 from a differnt servo....

Dont know how cooler air can cause det??? Tuned on 33 deg day and knocking on 18 deg day? Cooler denser air = less prone to det....

My money would be on a shitty batch of fuel...seems to make sense in that the more boost you pull out of it the less it pings....

Safe bet is on the fuel....Get a good octane booster and fresh fuel in it...

[Marko R1]

This is the thing, I've run 2 batches of fuel through it with the same symptoms

[wolverine]

cooler air = more O2

[R31Nismoid]

& more O2 means leaner... So not sure what NSNPWR is talking about exactly...

Air temp in terms of intake temps is not as important as the amount of the airs vs timing vs fuel etc.

I still don't think it's fuel, i still vote for a cell or two off as what you describe fits it.

Wait and see what the tuner says... as for your other light throttle 20-25 knock, thats irrelevant as everyone gets that

Could also be a faulty sensor but doesn't sound like it @ this stage

[paulr33]

if its knocking that much at 3000rpm on light load id say a sensor is loose or something near the sensor is loose

if you can replicate the knocking at 3000rpm or just below and have time to do a map tracer via MONITOR, MAP TRACE and press UP once on this screen, try and pinpoint which cell it is using when it knocks around that level. you can then view the cell values for IGN and INJ under SETTING, IGN or INJ. obviously its a bit fiddly and sometimes best left to a tuner, but if you have patience and are interested you could try that. perhaps the cell it's using has some wierd timing (unlikely but possible) otherwise id say something mechanical is loose

if you want to debunk the ignition timing / fuel / load etc drive the car, replicate the knock levels you are seeing

then goto SETTING, INJ/IGN and back out 5deg of timing, so you make IGN -5 and then continue to drive around

check out the knock values then, if its still knocking the same levels id say your issue is mechanical noise the sensors are picking up

if the knocking stops when you back out 5deg post up here and we can look at what it might be (fuel, mapping, something else whacko)

[Marko R1]

if its knocking that much at 3000rpm on light load id say a sensor is loose or something near the sensor is loose

if you can replicate the knocking at 3000rpm or just below and have time to do a map tracer via MONITOR, MAP TRACE and press UP once on this screen, try and pinpoint which cell it is using when it knocks around that level. you can then view the cell values for IGN and INJ under SETTING, IGN or INJ. obviously its a bit fiddly and sometimes best left to a tuner, but if you have patience and are interested you could try that. perhaps the cell it's using has some wierd timing (unlikely but possible) otherwise id say something mechanical is loose

if you want to debunk the ignition timing / fuel / load etc drive the car, replicate the knock levels you are seeing

then goto SETTING, INJ/IGN and back out 5deg of timing, so you make IGN -5 and then continue to drive around

check out the knock values then, if its still knocking the same levels id say your issue is mechanical noise the sensors are picking up

if the knocking stops when you back out 5deg post up here and we can look at what it might be (fuel, mapping, something else whacko)

I can't get into the pfc as crd lock their tunes.

Paulr33 - I will look at the knock sensors and assoc plugs to make sure all is secure as I also think it might be mechanical, if it looks ok then its off to crd.

[NSNPWR]

& more O2 means leaner... So not sure what NSNPWR is talking about exactly...

Air temp in terms of intake temps is not as important as the amount of the airs vs timing vs fuel etc.

I still don't think it's fuel, i still vote for a cell or two off as what you describe fits it.

Wait and see what the tuner says... as for your other light throttle 20-25 knock, thats irrelevant as everyone gets that

Could also be a faulty sensor but doesn't sound like it @ this stage

Not sure what youre talking about either and im not sure youre sure what youre talking about....

Using your logic above my car shouldnt knock on hot days as the mixtures would be RICH due to less o2 and more fuel??? This is exactly the opposite to what actually occurs...on a hot day, the car is more likely to knock due to the hot intake temps...sooooo, I believe this contradicts your statement about inlet temps not being as important as the amount of air??? vs timing vs fuel etc.....? Inlet air temps are directly related to knock levels, fact.

The only reason it would knock with cold, dense air is from the turbo making a few extra psi, creating potential for lean A/F ratios depending how much fuel the tuner left in it originally....

As for your theory of it being a cell, its not something that he's noticed before by the sounds of it so unless that cell magically changed itself, I cant see how all of a sudden its started giving these high knock readings?

Did you get the fuel form the same servo MarkoR1?.....

Edited April 8, 2010 by NSNPWR

[Marko R1]

Fuel was from 2 different servos just to further confuse u hehe, I don't think its fuel related.

I understand that lower temp does introduce more 02 but I also agree with NSNPWR in that an engine is more likely to knock in higher heat than when its cooler

[krzysiu]

Think ash is right. Took the car for a good drive last night when it was really cold and the car pings. But i have realised when it's a bit warmer it does not

[R31Nismoid]

Air temp is not the only factor in knocking.

Fact is you are talking a few degree's anyway, its not as major as you are making it out.

The issue is the denser air vs fuel vs the loading cells you hit as a result.

[aerofocker]

check your afr with a wideband. have you got oil in your intercooler pipes,eg turbo leaking oil?How is engine blow by? does it idle nice? oil in the charge will increse the engines tendency to det,so will a cracked ringland.......... has the vacume feed to you fpr came off? has the cas been moved recently? is there somthing loose or tapping in the engine bay?possible carbopn depposits in the combustion chamber? the bad news is if knok gets less when less boost is being applied,then it probably is real and unless you have forged pistons and even then you are going to damage your engine if you keep driving it with this knock. hows you fuel pressure?

Edited April 8, 2010 by aerofocker

[paulr33]

even with a locked tune, you can still use the temp IGN adjust to back out -5deg of timing

this would be the quickest and fatest way to isolate tune/mapping/cells vs other stuff causing it

[NSNPWR]

Think ash is right. Took the car for a good drive last night when it was really cold and the car pings. But i have realised when it's a bit warmer it does not

You sir are an idiot...sorry.

[R31Nismoid]

Because he has factual evidence that disproves what you are saying?

lol... nice.

[NSNPWR]

Air temp is not the only factor in knocking.

Fact is you are talking a few degree's anyway, its not as major as you are making it out.

The issue is the denser air vs fuel vs the loading cells you hit as a result.

I know its not the only factor but its equally as important as timing/fuel etc and will to an extent determine how much timing you can actually run...

A 15 degree difference in ambient temp is not just 'a few degrees' it is significant and the difference in the under bonnet temps would differ more than 15 degrees on the 2 days...

For cool, dense air to induce knock the tune must have been right on the edge as it was and unless the car is making more boost from the cooler air then I do not believe it would cause lean mixtures.

Ive never heard of anyone retuning for winter or cooler conditions (maybe adjusting boost controller) but I have for hot conditions for obvious reasons.

And re your post above, are you suggesting cold air is more likely to cause knock over hot air? Lol.................is this nissansilvia.com?

Do you consider the word of some random 'Ash' groupy on the internet 'fact'? Lol................

Edited April 9, 2010 by NSNPWR

[TiTAN]

some random 'Ash' groupy

[NSNPWR]

Well, seems the man can never be wrong and when a few people disagree with something he says...in come the Vic Club members...lol.

Its a pretty simple question, would you rather flog your car on a 35 degree day or on an 18 degree day? Would you even bother flogging your car on the 35 degree day?

[aerofocker]

hot weather,cold weather,pissing rain the engine shouldnt knock over 25 on a power fc.det leads to walking

[Marko R1]

i can understand both sides, i.e:

1. ash with more O2 = leaner & subsequent higher boost (does make logical sense)

2. nsnpwr that higher air temp will cause pinging (i have experienced this in the past)

in fact, the 1st question i asked my tuner when it was done "is it safe to push on hotter days?"

in my other gtr i remember my tuner telling me "the tune is safe, when it gets hotter though maybe take 2psi off the controller for that extra buffer"...this suggests to me that nsnpwr is right.

i think both of you are right in your own way

[Marko R1]

check your afr with a wideband. have you got oil in your intercooler pipes,eg turbo leaking oil?How is engine blow by? does it idle nice? oil in the charge will increse the engines tendency to det,so will a cracked ringland.......... has the vacume feed to you fpr came off? has the cas been moved recently? is there somthing loose or tapping in the engine bay?possible carbopn depposits in the combustion chamber? the bad news is if knok gets less when less boost is being applied,then it probably is real and unless you have forged pistons and even then you are going to damage your engine if you keep driving it with this knock. hows you fuel pressure?

you're freaking me out lol

its a fresh engine with only 1500km on it, forged etc with all of the 'ducks nuts' in terms of hardware.

engine does blowby at times but its expecting when running 24psi & 700bhp.

not sure about turbo pipes but again my turbo's are new.

idle is good grrrrough & lumpy.

i will check all hoses i.e. fpr & other plumbing. can i test my knock sensors?