new boy

hello.
i am a new ower to a my96 uk turbo.
i went to a garage recently and when they did the r/road-they said it was pinking....i am running it on superunleaded with no additives.
its a basic motor with just and biger exhaust but a k&n induction kit both fited by prev owner.
any help-not sure what they mean?
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scoobyslut

Are you sure that it is pinking, and not a bit of piston slap, as they do sound very similar.

Dizzy

I would be very supprised that your knocking without upping the boost. I have a MY96 too. I would advise getting a knocklink (its just a way of seeing when your pinking / knocking). I got mine from BRDevelopments.

could be a variety of reasons though. (I just asked the same question on my own thread )

greasemonkey

Some induction kits can make the car's mass air flow sensor under-read - making it run lean, which in turn makes it det (pink). The K&N 57i kit is supposed to be fairly safe in this respect, but it's always better to be safe than sorry. Some exhausts can also promote boost spiking, which itself can lead to det.

Buying a KnockLink is by far the safer option. Look here.

Ex_Pug

I allways thought pinking and knock/det were different things?

ozzy

nope, pinking is the description of the metallic sound produced by det/knock. all one in the same AFAIK.

Stefan

new boy

cheers lads...
in the meantime would it be worth adding an additive to the petrol to cover my engine till i sort something out??
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-rocky-

"I allways thought pinking and knock/det were different things? "



THEY ARE

cannot remember the difference off the top of my head but i'll be back with the answer shortly

Ex_Pug

Well, as I had originally thought, pinking is caused by ingition being set too far advanced, causing the mixture to combust before the piston is ready for the down stroke, and Knock, or pre-detonation, is caused by the mixture being ignited by something other than the spark from the plug, again, causing it to burn at an in-apropriate time in the cycle.

new boy

one last thought

i fitted a strut brace in the last 2 weeks or so.
noticed a few nights ago it had rubbed rear edge of intercooler...could that be causing the strange noise the garage heard?

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nom

Detonation is detonation, not pre-detonation: pre-detonation & you have a hole in your piston through the ignition taking place before TDC; detonation is after TDC, just too early, and makes a pinging sound - it stresses the engine, but the odd bit of det isn't a disaster. Sustained det can overheat the cylinder leading to pre-det, which is the bad thing
I always thought det/ping/pink were all the same thing - det makes a pinging noise, so it can be called pinging. Pinking was made up by someone with bad hearing
...and that's getting seriously off subject so drifting back...
(no, I don't have any useful comments except that lobbing in NF or similar is a good precaution until it's sorted, yes )
The strut-brace shouldn't make the same noise, no. It's very 'particular', det/pinging/pinking/whatever .

hypoluxa

Pre-ignition is combustion taking place before the spark.

Detonation or pinking is an uncontrolled and rapid explosion of the air/fuel mix which creates extreme cylinder pressures and temps. Pre-ignition will more then likely result in detonation.

new boy

i just took off the strut and it had been rubbing against the intercooler.i started the motor and it kept dying after a few moments....oh bugger i thought,
then i noticed a hose/junction from the thick hose behind the black box/to which is fasted the induction kit.(sorry to be 2 technical there...
i fastened it up again and its running fine-could that loose conection have been causing the pinking noise/problem?
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Ex_Pug

For anyone interested.. http://www.wikipedia.org/wiki/Engine_knocking

nom

Still trying to work out exactly what you mean - too technical for me but potentially, yes, that sort of thing could easily cause the problem. Not too sure about which hose you're on about, but that's all near the MAF, which is a very important & touchy bit of kit - and is the typicaly cause of mis-fuelling (usually under fuelling), which is the typical cause of det...
So, yes

Dizzy

<offtopic>
ok... Knock / pinking / pinging / det are all the same thing and are where the mix is set off buy the plug. PRE detination is where the mix ignites of its own accord (ala desiel engines) NOT buy the plug.

as the piston rises in the chamber you want the mix to be at "full burn / max combustion" when the piston is TDC (top dead centre) i.e. putting the mix under max compression. Because it takes a small amount of time for the mix to burn the plug fires slightly before the piston reaches TDC making it fire earlyer is called "advancing" the ignition and making it happen later is "retarding".

Knock is where the burn has happened too quickly and bounces off the piston as it is still rising (the pinging sound).

That other link is much better at describing it though

All of the above is what I belive and is probably wrong
</offtopic>

Gedi

I have also always been advised that knock, det and pinking are exactly the same thing, the miture burning before the spark ignights it.

Dizzy

No, I think you missunderstand.
(taken from above link)

nom

Well, I agree with you Dizzy - that was what I was thinking, just not writing
So that's two of us probably wrong, then...

SiHethers

I thought knock was when some of the charge in the cylinder ignites before it has been reached by the flame front of the burning charge ignited by the spark plug. This can be caused by a hot spot within the combustion chamber (e.g due to carbon build up), or more frequently (in our cars) auto-ignition of the charge -due to it reaching the temp at which it self combusts (or something like that).

My understanding was that this occurs because the pressure and temp in the unburnt charge increases as the controlled burn propagates throughout the chamber, and if this reaches a certain level (ie the autoignition point of the fuel) you get knock. Hence if you have a higher pressure or temp to start with (i.e. more boost/higher charge temp) or you ignite the charge too early in the compression stroke (ie too much advance), the more likely you are to get knock.

Does that make any sense?

Simon

Ex_Pug

That does make sense yes, but the link I posted above seems to refer to this as pre-ignition (what I meant when I said pre-detonation up there somewhere^^), and describes knocking as being the same as pinking. Pinking I allways thought was caused by incorrect ignition timing/bad fuel, causing the spark plug to ignite the mixture too early for the respective cylinder position.

I remember with the 205 GTi I used to have, it was basically the case that if the car could be heard pinking, the timing needed taking back a fraction. This was never knock as I used to understand it.

[Edited by Ex_Pug - 9/19/2003 2:26:39 PM]