Pinging... what causes it exactly? How is it avoided/fixed?

[Taily]

Originally Posted by Crazy Dazz

How the heck would you get CARBON build up in a modern engine?
Don't get me wrong, I have seen all sorts of crud in heads, but CARBON will simply burn, unless your engine is running way too rich.

Sudden onset pinging is most likely dodgy fuel. Something went out of whack in the blend and its "octane" rating is too low. Your car should compensate for this, but there's a limit to how far it will retard the spark.

If it persists, then I would start to suspect that something has gone wrong with the timing, so you have to start looking at sensors, etc.

Quite easily, besides carbon will not burn unless it is in an aerosol (soot like) state.

Lots of very short distance trips, a thermostat that opens early or has been changed because "cooler is better", dribbling injectors, glazed bores/blowby/faulty PCV etc will all either cause or contribute to it.

You hit the nail on the head about sudden onset pinging. Most likely a load of fuel, however many people see any car without chrome bumpers as "new" so go easy on us...

The noise you all associate with pinging is not the actual uncontrolled burn in the cylinder, it is the piston momentarily rattling sideways in the bore and ringing like a bell...

[Davehoos]

carbon is a lubricant.

exhaust-lots of carbon is re-fed back into most engines [not falcon] to detune them at cruise and save fuel and reduce pinking. sound funny that the item to reduce pinking can create it.

massive market selling crankcase breather filters to reduce intake and cyl crud-but the crud is designed in to work as a lubricant.

lot of misunderstanding around. In days of old you removed the head to decoke and refresh the engine. because the engine wore out about the same time.
engines tech gets better so they extend the time to decoke and replace head bolts, only extend not cancel.

if you dribble the crankcase breather on the ground and into a container you still need to repair the damage from low lubricant--until ceramic engines wont require lube.

[Peter B - CV8]

Originally Posted by Crazy Dazz

How the heck would you get CARBON build up in a modern engine?
Don't get me wrong, I have seen all sorts of crud in heads, but CARBON will simply burn, unless your engine is running way too rich.

Sudden onset pinging is most likely dodgy fuel. Something went out of whack in the blend and its "octane" rating is too low. Your car should compensate for this, but there's a limit to how far it will retard the spark.

If it persists, then I would start to suspect that something has gone wrong with the timing, so you have to start looking at sensors, etc.

Dazz, It's a real issue with direct injection motors - due to the lack of fuel wash over the inlet valve stems & inlet ports etc.

[Crazy Dazz]

Originally Posted by XR6 Martin

Carbon build up in a BMW M5 engine (E39)

image

And a Mini Cooper (direct injected BMW engine)

image

So, because its black, you assume its carbon?
It is mostly ceramified heavy ash, principally metal oxides & related salts.
It possibly includes some polymerised hydro-carbons, depending on the quality of the fuel and how lean the engine was running.

As for removing it? Without removing the heads? I have no idea.
There's nothing I think would remove it that I would want to pour into my engine.
I'd be interested to hear if the water treatment really does work?

Interesting that on the Mini engine there is build-up BEHIND the INLET valve

[Crazy Dazz]

Originally Posted by Peter B - CV8

Dazz, It's a real issue with direct injection motors - due to the lack of fuel wash over the inlet valve stems & inlet ports etc.

Yeah, I could see that in the Mini engine, build up behind the inlet valve.
HOW does it get THERE???
Is that from burnt oil? I can see that would be mostly carbon, and it wouldn't burn off since the valves are closed when the engine fires.
Again, how would you clean that? Pour a solvent down your manifold?

[XR Martin]

Interestingly Toyota's direct injected engines also still have injectors in the ports.

[GASWAGON]

Originally Posted by XR6 Martin

Carbon build up in a BMW M5 engine (E39)

image

And a Mini Cooper (direct injected BMW engine)

image

Gees both of these pics are BAD for late model engines.....Can't believe the intake ports of the Mini???

[Davehoos]

EGR-exhaust gas recirculation.

engines with lots of cam overlap can pulse exhaust back up the intake.and often multi valve engines often close off on port at low RPM.

sometimes it just hot running engine-when you stop the engine the oil fries and leave a random deposit.

rich mixture has nothing to do with this carbon. it would be more down at the cool end of the exhaust. lean burn engines still create carbon soot.

there has been a massive industry in carbon removal, including the fuel bowser. the only way is a cyl off decoke.

[Franco Cozzo]

If you've got a turbo car, water/methanol injection cleans all the carbon build up right out of an engine. It works really well on diesels.

[marty351]

Originally Posted by XR6 Martin

Carbon build up in a BMW M5 engine (E39)

image

And a Mini Cooper (direct injected BMW engine)

image

Those engines look like an old chimney!
How does so much carbon build up on an inlet port?
When I rebuilt my scorpion head at 200,000km only a small amount of coke buildup on cylinder heads and pistons was present and virtually nothing on inlets and exhaust ports.
The bloke I took it to was suprised it wasnt a turbo it was so clean.
Anything to do with quality of fuel?

[Davehoos]

mitibishi engines are normally lean burn engines so they run hot consuming all and dreadfull water heat choke operation.

astron -engine-in local OZ spec scorpion would have an egr that prob didn't work and ive seen some imports with a second egr that had a cam operated jet valve. also ive never seen these operate. top that with most of thes engines the crankcase is not sealed system.

most of the astrons I been involved with had valve stem issues and you get coke on the topside of the valve head, to fix this they counter sunk the top of te guide and allow the crud to stay up there.

[johnydep]

Originally Posted by XR6 Martin

Carbon build up in a BMW M5 engine (E39)

image

And a Mini Cooper (direct injected BMW engine)

image

Incorrect engine oil may cause that. Some additives in the oil leave an ash residue, some base oils are more volatile that others - oil vaporises & is drawn into intake system.

A lot of the European manufacturers have been specifying specific oils for a while now. I have 7 different 5W30 engine oils in stock, to cover most of the market.

Yes, you can get away with using a multi-purpose oil. However, in the long term things do happen that most owners do not like - excess ash/carbon build up, oil leaks, rattles.

[esppwr]

Originally Posted by XR6 Martin

Interestingly Toyota's direct injected engines also still have injectors in the ports.

They are for high rpm operation, direct injection is good for low and mid rpm but as the time for the fuel and air to mix reduces at high rpm, it's beneficial to inject it in the inlet port to aid atomisation.

Egr is used to reduce pumping losses at small throttle openings. It uses the exhaust gas as an inert gas to take up space in the cylinder which requires a larger throttle opening to make the same power. This reduces pumping loses and increases efficiency at low load. The system deactivates at mid to high load

[mac_man_luke]

EGR is also a lot about emissions. Worst invention ever.

[johnydep]

Originally Posted by mac_man_luke

EGR is also a lot about emissions. Worst invention ever.

Part of the reason some manufacturers specify low ash/low volatility oil.

[ebxr8240]

EGR is an inert gas .. So it cools chamber.. Usually activates on light throttle on cruise.. Ignition advance is often quite aggressive to get good cylinder burn to improve emissions .
Generally lean mixture and too far advanced timing under load brings on detonation as it raises cylinder pressures.. Oil in chamber from PCV promotes detonation also.. Simple oil separator fixes .. Restricted exhaust / blocked cats too..

[rjr]

Originally Posted by zilo

Doesn't this car have a knock sensor in the ECU?

If it does then something is broken.

Either google it or check a workshop manual and see if that model has a knock sensor.

The ecu will adjust the timing so the engine doesn't ping and you can run it on the recommend fuel.