Time for a simple one...

[Bluebottle]

A question close to my heart, being the owner of a 1984 Granada 2.3 LX, running unleaded + additive....

What is Pinking?
What causes it?
Why is it called Pinking?

That'll do for now,
I'm off to borrow a timing lamp.....

[KC]

In the States we call it pinging because that is what it sounds like. I think it is caused by pre-detonation, or the fuel and air mixture firing before the spark plug does it. This happens too early in the compression cycle and can damage rod, rod bearings and piston as it is still travelling upwards when the mixture fires.

[Bluebottle]

So if it occures in a car fitted with a catalyst, it would be pinging and ponging?










er....I'll get my coat.

[yelwoci]

This isn't an advert but we have a 1985 Ford Fiesta 1.1L which is not suitable for unleaded fuel.

Running on Lead Replacement Fuel (laugh!) rubbish it pinks like gravel in your hub caps! That's despite my tuning efforts.

I now run Unleaded (95) with Millers VSP which works a treat and also covers the extra cost (@£3.50) with better mpg.

IMHO don't use LRP, potassium, sodium or phosporous based additives, especially if you have a turbo.

Regards
Ianc

[davel]

This is the best description that I have come across for pinging (or Pinking). It is in the tech area of the NGK site (http://www.ngksparkplugs.com/techinfo/spark_plugs/overviewp5.asp).

"Most frequently caused by hot spots in the combustion chamber. Hot spots will allow the air/fuel mixture to pre-ignite. As the piston is being forced upward by mechanical action of the connecting rod, the pre-ignited explosion will try to force the piston downward. If the piston can't go up (because of the force of the premature explosion) and it can't go down (because of the upward mo-tion of the connecting rod), the piston will rattle from side to side. The resulting shock wave causes an audible pinging sound. This is detonation. "

Like I said, I haven't seen it described any better than that short paragraph. The is some useful info regarding plug temperatures etc on that site. Good to see a manufacturer providing *useful* information in their "Technical" area for once

Cheers,
Dave

[Liz]

I always thought it happened when you used cheap gasoline. That is, the impurities in the gasoline caused it.

[Sparky]

Well, dear Bluebottle has two out of three answered!
So far, the name and the description.

I'll try and suggest what causes it!

As Liz mentions, 'cheap' fuel in an otherwise healthy engine is the most common cause, although impurities are not the reason for detonation.
The reason for the pinking is using fuel with too low an octane rating.
Octane is a property of fuel, and and is added to increase the detonation resisitance. The amount of octane added is indicated by a rating, the Research Octane Number. I believe the unleaded fuel we have here in the UK is around 89 RON. Aviation fuel, on the other hand, has something like 110 RON. In some parts of the world, the RON can be as low as 75!
Race-tuned engines that use lots of compression need high octane fuels, otherwise as KC says, damage can occur.
Economy engines with smaller power outputs can get by with lower octane fuel.
But there are many other reasons for detonation or pinking to occur.

If the fuel used is marginal, but OK in most circumstances, then using an engine under high load will cause pinking. I'm sure most of us have tried getting up that 1 in 4 gradient in top gear. The engine doesn't like it and rattles like "gravel in your hub caps!" Thanks Ian!

Using a spark plug that is rated 'too hot' can cause this too. Why not use 'cool' plugs? They can foul easily if the heat isn't there to burn off combustion residue.

Incorrect ignition timing. As Bluebottle mentioned, reaching for that timing gun can, in most cases, improve the situation. Too much ignition advance can cause detonation, and can also sometimes make the engine behave like the battery is discharged. Too little, or retarded timing, can cause pre-ignition. This is when the engine runs on for a short while after the engine has been switched off. Modern ignition systems no longer make use of the points and condenser that were once the norm. In fact, most systems today make use of a 'knock' sensor that automatically reduces ignition timing to reduce pinking.

As davel says, 'hotspots' in the combustion chamber will also cause pinking. This can take the form of carbon deposits, or even a section of damaged head gasket exposed to combustion. (If this is the case, you'll probably have more than pinking to worry about!!)

If any one of the above situations occurs, then an engine can 'pink' or detonate itself to destruction if left unchecked. The problem gets a lot worse when a combination of the above happens, and as cars get older, and service standards drop, this easily happens.

Poor fuel, incorrect plugs, carbon deposits, advanced timing and others can mean an engine will run (just!) but won't last long. Especially if you drive it like you hate it!

[Bluebottle]

Thanks chaps, some usefull stuff there, Davel's description is the best I've come across as far as the cause of the sound goes!
The Granada's pinking seems to be an octane problem- it ran really nicely on Super Unleadded which is a higher octane rating, but I've heard that it is more poisonous- is this true?

[THR]

not being a greenie myself. who cares if its more poisonous!! long as u dont suck on the exhaust pipes!

[Sparky]

long as u dont suck on the exhaust pipes!

...But that's half the fun...!

[THR]

hmmm, we are still talking about cars here? and thats not a sexual reference? arent u married???
LOL

[Sparky]

Er, yes... Cars. I was definately talking cars.

[DAVID PATERSON]

My dog sucks on exhaust pipes, she puts her whole mouth over the tailpipe, gets a big hit, runs a lap of the car, gets another hit, runs another lap.......it just goes on till the car drives away or the engine is switched off. she has absolutley no interest whatsoever in anything that doesn't move. She also bites the wheels on lawnmowers and garbage bins, but only if they're moving. One crazy dog.

[paul c]

But going back to the poisonous question....
Yes, so I'm told, it is true. The processes involved in formulating super-unleaded mean that you have a higher benzene level, and benzene is a known cancer causing chemical. There's little doubt that super unleaded is worse for health than leaded ever was. Actually, I've heard the same said about ordinary unleaded too....

Anyhow, if you use super-unleaded, turn your face away and avoid breathing the vapour or getting it on your skin. I used to work in a lab., and you wouldn't believe the regulations for any experiment that required benzene.

[Sparky]

So you'd recommend I stop syphoning Super-unleaded petrol straight away then, Paul?

[THR]

but motor racing is worth all risks!!!

i could not EVER give up motor racing even if it did give u a deadly deasease!!

its the Buzz i tell u!!