WHAT IS "PINKING"

[rnd]

Hi there, can anyone tell me what is pinking. I know it is usually lean mixture or timing off etc but what I want to know is what is the noise that I am getting. It sounds frighting.
Thanks

Edited by rnd on Saturday 5th June 21:42

[dan19evans]

rnd said:

Hi there, can anyone tell me what is pinking. I know it is usually lean mixture or timing off etc but what I want to know is what is the noise that I am getting. It sounds frighting.
Thanks

Edited by rnd on Saturday 5th June 21:42

i think pinking is what you get when your engine timing is too far advanced. on newer cars there is usually a sensor that detects pinking and adjusts the ignition timing so you dont get it

[Boosted LS1]

Pinking or preignition can sound like leaves rustling in the exhaust headers through to a tinkling noise behind the dashboard. When it gets bad it can sound like tapping and then it's becomes detonation and you may hear knocking noises and that's serious.

[dan19evans]

yeh in serious cases of pre-ignition you can blow holes in your piston.. a bloke i know showed me some pistons with holes in them caused by pre-ignition

[Yuxi]

dan19evans said:

rnd said:

Hi there, can anyone tell me what is pinking. I know it is usually lean mixture or timing off etc but what I want to know is what is the noise that I am getting. It sounds frighting.
Thanks

Edited by rnd on Saturday 5th June 21:42

i think pinking is what you get when your engine timing is too far advanced. on newer cars there is usually a sensor that detects pinking and adjusts the ignition timing so you dont get it

That will be the knock sensor...........

[dan19evans]

Yuxi said:

dan19evans said:

rnd said:

Hi there, can anyone tell me what is pinking. I know it is usually lean mixture or timing off etc but what I want to know is what is the noise that I am getting. It sounds frighting.
Thanks

Edited by rnd on Saturday 5th June 21:42

i think pinking is what you get when your engine timing is too far advanced. on newer cars there is usually a sensor that detects pinking and adjusts the ignition timing so you dont get it

That will be the knock sensor...........

that will indeed i didnt put knock sensor incase he didnt know what it was

[Boosted LS1]

I was recently surprised to read that on some engines the spark plugs are used to sense knock. Must be something to do with a change in voltage being detected by the ecu. Maybe the high cylinder pressures caused by knock stop the plug firing normally and the ecu detects that moment.

[stevesingo]

The V8 M3 engine uses this. Very clever.

http://delphi.com/manufacturers/auto/powertrain/ga...

Boosted LS1 said:

I was recently surprised to read that on some engines the spark plugs are used to sense knock. Must be something to do with a change in voltage being detected by the ecu. Maybe the high cylinder pressures caused by knock stop the plug firing normally and the ecu detects that moment.

Steve

[Boosted LS1]

^ Thanks, it's very clever. I think my old trionic saab 9000 has something like this.

[stevesingo]

Only a matter of time before someone brings out an after market ECU with the feature.

Steve

[annodomini2]

Boosted LS1 said:

^ Thanks, it's very clever. I think my old trionic saab 9000 has something like this.

Very simple, which for the most part the best ideas are.

Basically a current sensor in the HT side and a map to determine what the current should be for a given set of conditions, the clever bit or hard work depending on your perspective is the map.

There may also be benefits in multi-fuel engines, being able to compensate for the different ignition requirements of different fuels.

[annodomini2]

To clarify the original question:

'Pinking' or Pre-ignition is when the temperature/compression combination within the cylinder is high enough to cause ignition of the fuel/air mixture, without the use of a spark plug.

The main issue is that pinking tends to be uneven in its combustion with little micro-explosions. If this explosion occurs close to a surface it causes pitting, too much and it can cause the holes in pistons mentioned above.

The pinging noise are these micro-explosions and the resulting shockwave they produce.

It's caused by a combination of fuel/air mixture, temperature, physical layout of the chamber and compression ratio.

Ignition Advance being too late is sometimes the problem on a good engine, but it is also often used to mask other issues, lean mixture is easy to spot, but others such as burrs in the machining of the components causing hot spots, are less so without disassembling the engine.

Additionally if pinking has occurred, it is more likely to occur in the future especially where damage has resulted, creating more opportunities for hot spots.

It is also more prevalent on boosted engines due to the higher pressures and temperatures involved.

[Boosted LS1]

^
"The pinging noise are these micro-explosions and the resulting shockwave they produce".

Which can make the block walls resonate, makink a ringing noise.

[Yuxi]

The development engineers at work call it "det" (detonation)

[stevieturbo]

I wouls say two different, but similar things


Pinking directly caused by too much advance. Not so much an "uncontrolled" explosion. Just one deliberately started too early.

Detonation is literally that. An explosion that has started without a spark from the plug.

[Zad]

When fuel burns, it ionises the gas to some extent, this means that the gap in the spark plug becomes slightly conductive. Sensing this gives an indication of when the mixture burned.

[rnd]

Thanks annodomini2 that was a good and simple explanition.

[Stu R]

Boosted LS1 said:

^
"The pinging noise are these micro-explosions and the resulting shockwave they produce".

Which can make the block walls resonate, makink a ringing noise.

Skeletons w@nking in a biscuit tin is the best analogy I've heard

[SDxsi]

So how does an anti-lag system work without causing 'det' then? I'm just curious.

[stevieturbo]

SDxsi said:

So how does an anti-lag system work without causing 'det' then? I'm just curious.

anti lag has fk all to do with detonation. How could it possibly cause detonation ?

It's a deliberataly timed and controlled burn.