What is pinking?

[Carl Collins]

Never got my head around this?

Is it something to do with spark plugs?

 

[John Ricketts]

It is a secondary ignition, caused by compression, remote from the sparkplug. If for instance the timing is set too advanced, then the peak pressure in the cylinder can exceed the normal limits and you get compression ignition occuring (like in a diesel engine) when it shouldn't. Can also be caused by wrong grade of fuel, or excessive throttle opening at low engine speed for instance.

Did a lot of work on this on a Ricardo E6 experimental engine many moons ago....... ah... those were the days........

 

[Rick Maninov]

Never got my head around this?

Is it something to do with spark plugs?

Not really.
It's pre-ignition of fuel in the cylinder, that is ignition before the spark lights it up, and of course being at the wrong place (before the piston reaches top dead centre) it puts an awfull stress on the piston/con-rod/crankshaft and gives a distictive knock noise. It's diesel-like detonation usually caused by using a lower grade of fuel than that recommended for the compression ratio of the engine. As previously stated extremely advanced ignition timing will also give this symptom.

Rick.

 

[steve (archive)]

another description as follows:
under normal conditions the spark will ignite the fuel just before the piston reaches top dead centre, this is done to account for the time it takes for the fuel to explode and force the piston away, by the time this happens the piston should be just past top dead centre and this is what keeps the engine running. pinking is what happens when the fuel is ignited too early and instead of forcing the piston away in the direction the engine is turning, it tries to turn the engine the opposite way since the piston hasnt reached top dead centre yet. of course it wont ever manage to turn in the opposite direction, the force is minimal and the momentum of the engine far exceeds this, however it does cause a knock which you can hear as a tinny rattle (pinking) this is cause when the ignition timing is too far advanced, also when you accelerate the vacuum unit on the distributor is advancing the timing even more so as is the centrifugal advance system, so with this in mind the timing has to be set up just right to prevent all this.
steve.

 

[Dave Baker]

Subject: Re: What is pinking?

another description as follows:
under normal conditions the spark will ignite the fuel just before the piston reaches top dead centre, this is done to account for the time it takes for the fuel to explode and force the piston away, by the time this happens the piston should be just past top dead centre and this is what keeps the engine running. pinking is what happens when the fuel is ignited too early and instead of forcing the piston away in the direction the engine is turning, it tries to turn the engine the opposite way since the piston hasnt reached top dead centre yet. of course it wont ever manage to turn in the opposite direction, the force is minimal and the momentum of the engine far exceeds this, however it does cause a knock which you can hear as a tinny rattle (pinking)

None of the above has anything to do with pinking

this is cause when the ignition timing is too far advanced, also when you accelerate the vacuum unit on the distributor is advancing the timing even more

No it isn't. The timing retards at high throttle openings.

Dave Baker - Puma Race Engines (www.pumaracing.co.uk) I'm not at all sure why women like men. We're argumentative, childish, unsociable and extremely unappealing naked. I'm quite grateful they do though.

 

[Steve B]

Apart from the comments in earlier postings, also note:
Many modern cars with computerised Engine Control Units (ECUs) have sensors stuck on the engine specially to detect "pinking". If they "hear" it happening, they automatically adjust the ignition timing to eliminate it, sometimes on a cylinder-by-cylinder basis. In this way, optimum ignition timing can be achieved even for varying grades of fuel.

- Steve

 

[steve (archive)]

None of the above has anything to do with pinking

it is exactly what pinking is, actually, i have described how it happens and perhaps if your not fammiliar with the concept then you don't understand it.

No it isn't. The timing retards at high throttle openings.

no it doesnt, actually it has nothing to do with throttle position, it is related to either engine speed, (in which case the centrifugal advance (if fitted) advances the timing)) or engine load, in which case the deppression in the inlet manifold will cause the vacuum on the distributor to advance. nothing retards the timing, except when already advanced by one of the above and its returning to its original position.

 

[Dave Baker]

Subject: Re: What is pinking?

it is exactly what pinking is, actually, i have described how it happens and perhaps if your not fammiliar with the concept then you don't understand it.

LOL. This is another of those "do you realise who I am sonny?" moments. Read some of the website or a good book like "The Internal Combustion Engine in Theory and Practice" by C.F.Taylor before you start arguing with the experts. Pinking, as with any other psuedonym for detonation, is the sound of pressure waves in the combustion chamber caused by pockets of fuel/air mixture auto igniting due to excess temperature and pressure before the spark ignited flame front gets to it. Read the post by John Ricketts who has actually worked on the subject.

It has nothing to do with combustion trying to push the piston back down the way it came or any of your other nonsense.

no it doesnt, actually it has nothing to do with throttle position, it is related to either engine speed, (in which case the centrifugal advance (if fitted) advances the timing)) or engine load, in which case the deppression in the inlet manifold will cause the vacuum on the distributor to advance. nothing retards the timing, except when already advanced by one of the above and its returning to its original position.

Struth. A vacuum advance unit advances the ignition timing when the pressure in the inlet manifold is low (small throttle openings) and retards it again when inlet manifold pressure is high (large throttle openings). It doesn't, and I quote

when you
It's the exact opposite of that.

Dave Baker - Puma Race Engines (www.pumaracing.co.uk) I'm not at all sure why women like men. We're argumentative, childish, unsociable and extremely unappealing naked. I'm quite grateful they do though.

 

[steve (archive)]

are you trying to be clever, because reading a pathetic web sites description and actually knowing due to 25 years of experience are 2 different things. i wont even bother to explain why you are wrong, you sound to me like some teenager who's read too many books but this isn't a slagging match, i know the difference and thats all that matters, what i do object to though is the original poster being fed immature opinions instead of the answer to his question. do your homework before posting in future. i bet you haven't even worked in cars with "proper distributors" modern cars don't have the same problems.

it.

LOL. This is another of those "do you realise who I am sonny?" moments. Read some of the website or a good book like "The Internal Combustion Engine in Theory and Practice" by C.F.Taylor before you start arguing with the experts. Pinking, as with any other psuedonym for detonation, is the sound of pressure waves in the combustion chamber caused by pockets of fuel/air mixture auto igniting due to excess temperature and pressure before the spark ignited flame front gets to it. Read the post by John Ricketts who has actually worked on the subject.

It has nothing to do with combustion trying to push the piston back down the way it came or any of your other nonsense.

Struth. A vacuum advance unit advances the ignition timing when the pressure in the inlet manifold is low (small throttle openings) and retards it again when inlet manifold pressure is high (large throttle openings). It doesn't, and I quote

when you

It's the exact opposite of that.

Dave Baker - Puma Race Engines (www.pumaracing.co.uk) I'm not at all sure why women like men. We're argumentative, childish, unsociable and extremely unappealing naked. I'm quite grateful they do

though.

 

[Dave Baker]

Subject: Re: What is pinking?

are you trying to be clever, because reading a pathetic web sites description and actually knowing due to 25 years of experience are 2 different things.

I meant my website then you'll know who I am and what I do.

i wont even bother to explain why you are wrong, you sound to me like some teenager who's read too many books but this isn't a slagging match, i know the difference and thats all that matters, what i do object to though is the original poster being fed immature opinions instead of the answer to his question. do your homework before posting in future. i bet you haven't even worked in cars with "proper distributors" modern cars don't have the same problems.

I strongly suggest you read up on what detonation is and also how vacuum advance systems work. It isn't an uncommon mistake for people to think they work the opposite way round to how they actually do. If you don't wish to learn though then by all means keep your head firmly buried in the sand.

As to "proper distributers" I've been setting them up since the 70s but it makes no difference if the timing under load is set by a vacuum advance unit or an ECU map. More advance is needed at low load and low throttle openings and less advance at high load and high throttle openings. If you understood how flame speed varies as the amount of mixture in the cylinder varies then it would become obvious and you wouldn't keep arguing an indefensible position.

Dave Baker - Puma Race Engines (www.pumaracing.co.uk) I'm not at all sure why women like men. We're argumentative, childish, unsociable and extremely unappealing naked. I'm quite grateful they do though.

 

[Rick Maninov]

I meant my website then you'll know who I am and what I do.

I strongly suggest you read up on what detonation is and also how vacuum advance systems work. It isn't an uncommon mistake for people to think they work the opposite way round to how they actually do. If you don't wish to learn though then by all means keep your head firmly buried in the sand.

As to "proper distributers" I've been setting them up since the 70s but it makes no difference if the timing under load is set by a vacuum advance unit or an ECU map. More advance is needed at low load and low throttle openings and less advance at high load and high throttle openings. If you understood how flame speed varies as the amount of mixture in the cylinder varies then it would become obvious and you wouldn't keep arguing an indefensible

position.

So you're saying it's nothing at all to do with cross-dressers wearing rouge when out on a date? <g>

Rick.

..

 

[steve (archive)]

I meant my website then you'll know who I am and what I do.

don't care who you are, or what you do, completely irrelevent in this discussion.

I strongly suggest you read up on what detonation is and also how vacuum advance systems work.

self explanitory, "vacuum advance" what do YOU think it does, make the tea ????? have a close look dipstick, just for the record, mechanical diaphram connected directly to a cam system fixed to the distributor shaft.which suprisingly enough "advances the timing" at different levels depending on manifold depression.

As to "proper distributers" I've been setting them up since the 70s but it makes no difference if the timing under load is set by a vacuum advance unit or an ECU map.

MAP sensors do the same think dipshit, they read manifold pressure via vacuum pipes.

More advance is needed at low load and low throttle openings and

less advance at high load and high throttle openings.

?????????????????????????
low load and low throttle position would indicate an idle condition or similar, and YOU think this requires more advance ?????? fu*k me your funny. completely inacurate, but funny.

how about you explain why centrifugal advance, a mechanical cam device, relies simply and only on engine speed to advance the timing, if your confused as to which way it operates then perhaps you need a career change. McDonalds are hiring in our area.

Dave Baker - Puma Race Engines (www.pumaracing.co.uk) I'm not at all sure why women like men. We're argumentative, childish, unsociable and extremely unappealing naked. I'm quite grateful they do

though.

 

[Marc (archive)]

Apart from the comments in earlier postings, also note:
Many modern cars with computerised Engine Control Units (ECUs) have sensors stuck on the engine specially to detect "pinking". If they "hear" it happening, they automatically adjust the ignition timing to eliminate it, sometimes on a cylinder-by-cylinder basis. In this way, optimum ignition timing can be achieved even for varying grades of fuel.

- Steve

I don't see

first you state that pinking is a spontaneous combustion of fuel before the spark should do. Now you say engine's can detect that, and, by adjust the ignition timing correct it.

Given your earlier porting this is not something you could correct by timing as your car runs like a diesel and does not need spark plug at all.

Perhaps you can enlighten me. because i'm a diesel driver and could wel benefit from sparkplugs then.

 

[Dave Baker]

Subject: Re: What is pinking?

don't care who you are, or what you do, completely irrelevent in this discussion.

I see. So the fact that I design race engines and consult on, amongst other things, ignition systems and calibration is irrelevant to such a discussion is it? It's been a while since I came across someone on Usenet quite so prepared to pontificate on a subject without understanding it or so unwilling to listen and learn. They do say of course that arguing with an idiot makes you one too but hopefully someone following this thread will learn something from it.

self explanitory, "vacuum advance" what do YOU think it does, make the tea ????? have a close look dipstick, just for the record, mechanical diaphram connected directly to a cam system fixed to the distributor shaft.which suprisingly enough "advances the timing" at different levels depending on manifold depression.

Quite correct. It just works the opposite way to that which you think.

More advance is needed at low load and low throttle openings and

?????????????????????????
low load and low throttle position would indicate an idle condition or similar, and YOU think this requires more advance ?????? fu*k me your funny. completely inacurate, but funny.

It's really very simple grasshopper. Do try and pay attention if your mind isn't completely closed. The amount of ignition advance depends on the burn time of the fuel/air mixture. At a given engine speed, the longer this takes the earlier the spark has to fire if the mixture is to be fully alight by TDC. I trust this bit is self explanatory.

One of the biggest influences on burn speed is the amount of mixture in the cylinder. The more completely filled the combustion chamber is the faster the flame travels. This is because the more tightly packed the fuel/air molecules are the easier it is for the flame front to spread from molecule to molecule and traverse the combustion chamber. It's also influenced by the amount of residual burnt gases from the previous cycle which inhibit the flame as they are not combustible having already burned. Residual contamination is high at low throttle openings and vice versa. At full throttle the residual gases are flushed out more fully into the exhaust system by the incoming charge.

The conclusions should now be obvious. At low throttle (idle, cruise etc) the combustion chamber is only partly filled, residual contamination is high and burn speed is low. More advance is required to get the mixture alight by TDC. The vacuum advance canister achieves this by sensing the high depression in the inlet manifold and advancing the distributor. As the throttle opens more fully the inlet manifold pressure increases closer to atmospheric and the amount of advance is decreased again. At full throttle the vacuum advance falls to zero and only the centrifugal advance is determining the spark timing.

Please try and understand what inlet manifold depression is. The pressure in it is lower when the engine is "sucking" against a closed throttle. It's higher when the throttle is open and directly connecting the manifold to atmosphere via the carb. Vacuum isn't something that happens when the throttle is open - it's the opposite.

Dave Baker - Puma Race Engines (www.pumaracing.co.uk) I'm not at all sure why women like men. We're argumentative, childish, unsociable and extremely unappealing naked. I'm quite grateful they do though.

 

[G.T]

Hello Dave,

I'm reading this post with interrest since its beginning, and I'd like to ask you something...

Pinking is a kind of strain combustion, i.e an inadequate one, responsible for bad performance among other things (and I hope you get what I mean accross my unperfect english), right ?

In case of pinking, the ignition advance must be reduced, right ? And now, more hardware : pinking causes an acoustic noise change, isn't it ? May an ECU detect it through a resonator ? I've heard of pinking sensors

 

[steve (archive)]

this is called a "knock sensor" but don't bother trying to explain it to mr baker, he might throw some book at you and write a chapter on it. (wonder if he has a brother called danny?)

I don't see

first you state that pinking is a spontaneous combustion of fuel before the spark should do.

i never said that...........i would called that "pre-ignition" i think mr bollox for brains baker said that.

Now you say engine's can detect that, and, by adjust the ignition timing correct it.

that i agree with, but not many manufacturers have sucessfully incooperated it into a management system. rovers sytem for example was a disaster.

Given your earlier porting this is not something you could correct by timing as your car runs like a diesel and does not need spark plug at all.

who's car runs like a diesel??? and maybe if we could perfect pre-ignition then hey, we might just be able to do away with spark plugs, but your bordering on mr bakers territory there.

Perhaps you can enlighten me. because i'm a diesel driver and could wel benefit from sparkplugs then.

nope because diesel relies on compression to ignite, not an introduced spark.

hope your learning mr baker.

 

[steve (archive)]

I see. So the fact that I design race engines and consult on, amongst other things, ignition systems and calibration is irrelevant to such a discussion is it? It's been a while since I came across someone on Usenet quite so prepared to pontificate on a subject without understanding it or so unwilling to listen and learn. They do say of course that arguing with an idiot makes you one too but hopefully someone following this thread will learn something from it.

Quite correct. It just works the opposite way to that which you think.

It's really very simple grasshopper. Do try and pay attention if your mind isn't completely closed. The amount of ignition advance depends on the burn time of the fuel/air mixture. At a given engine speed, the longer this takes the earlier the spark has to fire if the mixture is to be fully alight by TDC. I trust this bit is self explanatory.

big hairy bollox..............the amount of ignition advance on a standard distributor with both vacuum and centrifugal advance systems depends on the speed of the distributor and nothing else whatsoever for the centrifugal advance........(argue that point and your a tosser) and manifold pressure in the inlet manifold (which is where the vacuum advance system takes its vacuum from...duh) and that pressure in the manifold will depend on throttle position related to engine speed.....if your still unsure at which points a manifold will have maximum vacuum then try fitting a vacuum guage to one of your toy cars that keep rabbiting on about. by the way..............grasshopper???? you been watching too many karate kid movies..........

One of the biggest influences on burn speed is the amount of mixture in the cylinder. The more completely filled the combustion chamber is the faster the flame travels. This is because the more tightly packed the fuel/air molecules are the easier it is for the flame front to spread from molecule to molecule and traverse the combustion chamber. It's also influenced by the amount of residual burnt gases from the previous cycle which inhibit the flame as they are not combustible having already burned. Residual contamination is high at low throttle openings and vice versa. At full throttle the residual gases are flushed out more fully into the exhaust system by the incoming charge

this has absolutely nothing whatsoever to do with ignition advance or retard.
..

The conclusions should now be obvious. At low throttle (idle, cruise etc) the combustion chamber is only partly filled, residual contamination is high and burn speed is low. More advance is required to get the mixture alight by

TDC.

more big hairy bollox........if you need more evidence then try this.....connect your timing light and see what happens to the timing at different engine conditions...then come back and post...at low speed and idle the timing is more or less the same as static set timing (you are still with me right???) accelerate and watch what happens to the timing mark...........

The vacuum advance canister achieves this by sensing the high depression in the inlet manifold and advancing the distributor. As the throttle opens more fully the inlet manifold pressure increases closer to atmospheric and the amount of advance is decreased again. At full throttle the vacuum advance falls to zero and only the centrifugal advance is determining the spark timing.

Please try and understand what inlet manifold depression is. The pressure in it is lower when the engine is "sucking" against a closed throttle. It's higher when the throttle is open and directly connecting the manifold to atmosphere via the carb. Vacuum isn't something that happens when the throttle is open - it's the opposite.

you twat.........if thats the case then how do you expect a venturi to work..............

Dave Baker - Puma Race Engines (www.pumaracing.co.uk) I'm not at all sure why women like men. We're argumentative, childish, unsociable and extremely unappealing naked. I'm quite grateful they do

though.

 

[Marc (archive)]

i never said that...........i would called that "pre-ignition" i think mr bollox for brains baker said that.

that i agree with, but not many manufacturers have sucessfully incooperated it into a management system. rovers sytem for example was a disaster.

rovers in general are a disaster.
I just don't see, folowing your theory of early combustion, how you can correct pinking by introducing a spark in the first place ( because the damn fuel is already burning) and, giving tha variable timing of it when this spark should be introduced to the feul mixture

who's car runs like a diesel??? and maybe if we could perfect pre-ignition then hey, we might just be able to do away with spark plugs, but your bordering on mr bakers territory there.

My car runs like a diesel, it is one.

nope because diesel relies on compression to ignite, not an introduced spark.

it was said in a retorical way, I know a thing or two about diesel engines...

 

[ken kerrison]

Why don't you blokes enjoy your exchange of insults by email? This started off as an interesting thread until.... I have yet to see an abusive post anywhere, or a response to such a post, which does anything to advance humanity or knowledge.

 

[steve (archive)]

rovers in general are a disaster.
I just don't see, folowing your theory of early combustion, how you can correct pinking by introducing a spark in the first place ( because the damn fuel is already burning) and, giving tha variable timing of it when this spark should be introduced to the feul mixture

you dont correct pinking by introducing a spark, the spark is already there, the reason pinking happens is because the spark cuts in at the wrong time, ie: too early.

it was said in a retorical way, I know a thing or two about diesel engines...

mmmmmmm...not easy to emphasise sarcasm in a line of text.