V12 Misfire & Cat ingestion

[VanquishRider]

karatemaserati said:

On the subject of the well known independent who explains the problem and sells the cure, I think suggesting its a conflict of interest is a slightly cynical point of view and doesn't stack up... from a business aspect they'd be better off if they didn't offer the cure and just went on coining it from coil/plug changes and engine rebuilds.

Any tech can change coil and plugs, PCV systems etc. The "big" fix is seriously more expensive. Not saying it isn't needed. But the fear selling just doesn't sit well with many people.

[PHFS]

So almost a year on. Has anyone had misfires so the cats fail and take out their V12?

[Stratos7]

I've read a lot about it here and I've seen several videos on YouTube about misfiring and precat damage and the potential damages debris could cause to this v12 engine. I was looking for an Aston Martin here in Italy and, until a few weeks ago, I was determined to look for one of the few db9s present her but I changed my mind due to the problem with the pre-catalysts and so I started looking for a db7 vantage because I liked the idea of the V12 engine. Then a few weeks ago I saw a video about the ticking sound from the engine at idle and in the end I opted to look for a v8 vantage. In all honesty it is good to know all the possible defects thanks to online forum and videos but in my case that scared me a lot and made me change my mind about my purchase

[VanquishRider]

Stratos7 said:

I've read a lot about it here and I've seen several videos on YouTube about misfiring and precat damage and the potential damages debris could cause to this v12 engine. I was looking for an Aston Martin here in Italy and, until a few weeks ago, I was determined to look for one of the few db9s present her but I changed my mind due to the problem with the pre-catalysts and so I started looking for a db7 vantage because I liked the idea of the V12 engine. Then a few weeks ago I saw a video about the ticking sound from the engine at idle and in the end I opted to look for a v8 vantage. In all honesty it is good to know all the possible defects thanks to online forum and videos but in my case that scared me a lot and made me change my mind about my purchase

Just buy a V12 Vanquish Gen 1. Doesn't suffer the problem or depreciation.

[Stratos7]

VanquishRider said:

Just buy a V12 Vanquish Gen 1. Doesn't suffer the problem or depreciation.

Unfortunately I can't afford to buy a Vanquish gen 1. I wish I could but I can't

[Simpo Two]

Stratos7 said:

I was determined to look for one of the few db9s present her but I changed my mind due to the problem with the pre-catalysts

It's a pity when fear-mongering wrecks dreams. If you want a DB9, buy one. You can always have it checked for misfires for peace of mind, either with AMDS or a Foxwell with AM software. Dreams are worth fighting for

[Stratos7]

Simpo Two said:

It's a pity when fear-mongering wrecks dreams. If you want a DB9, buy one. You can always have it checked for misfires for peace of mind, either with AMDS or a Foxwell with AM software. Dreams are worth fighting for

you're right, the fear of an engine problem had this effect on me, combined with the ticking engine problem too.
where I live, in Italy, there is no Aston Martin center nearby and there are very few examples available. Now I'm looking for a v8 Vantage and I hope to find soon the right one for me

[PHFS]

I have had my V12VS for a year, and all good. This is why I asked the question above, seems these are just the edge cases or even urban myths with the odd failure, as any car has!

[CSK1]

I’ve had my V12VSR for almost 9 years now without any issues. Those engines are very reliable, I’ve mentioned the risk of cat ingestion to my dealer’s head mechanic and he said he never had a single case. At every service he carries out a misfire check.
My father in law owns an early DB9, he’s had some battery problems, mainly car not starting when left unused for too long but that’s it.
I’ve driven his DB9 and it’s a gem.
Don’t let a few internet comments put you off, buy a well maintained example and you should be fine.

[GT9]

Calinours said:

Jon39 said:

A graduate of combustion engineering has now explained, that because hydrogen has only approximately one third of the heating value of natural gas.

Sorry to add to the confusion, but it’s the other way around Jon..

Hydrogen 120-142 MJ/kg
Petrol 44-46 MJ/kg
Diesel 42-46 MJ/kg
LPG 34-52MJ/kg

The main problem with hydrogen is cost of production, either by heat intensive hydrogen reformation (to refine it from natural gas or methane) or electrically intensive electrolysis (from seawater). It also leaks too easily (simplest atom) presenting infrastructure and storage challenge, especially given the pressures required to move the required volumes of hydrogen around the system. That is perhaps what your combustion engineer friend was referring to, Hydrogen is so light the infrastructure needs to cope with high volumes.

Neither problem is insurmountable, if the production processes can be powered by renewable energy. There are projects already under consideration to produce hydrogen by directly electrolysing seawater at the base of huge offshore wind turbines using the turbines own energy.

There will always be applications requiring fuels with much higher energy densities than batteries are likely to be able to offer on the near future. Aircraft of all types, helicopters, long range drones, ocean going boats and all forms of transport in large and/or less developed countries where distances can be vast, and the consequences of running out of fuel potentially severe.

Anyway, apologies for thread hijack. Back to the issue (or non issue) of pre-cat ingestion

Edited by Calinours on Tuesday 30th May 12:24

Obviously I'm responding a year late, but I though I'd help clarify what the graduate was referring to.
You've hinted at it in your post, there are two energy density values relevant to the use of hydrogen (or any fuel for that matter), gravimetric and volumetric.
The gravimetric density is indeed very high, as you've stated.
It is however the volumetric energy density that is the challenge, for many applications, including onboard storage in vehicles.
At the same pressure, methane has a volumetric energy density 3 times higher than gaseous hydrogen.
Combined with the very small molecule size and hydrogen's capacity to embrittle many materials, it is certainly not a simple case of switching gases.
On the same topic, it's also why the statement I occasionally see on PH that 'hydrogen is just like petrol', when talking about the use of hydrogen in cars, is fundamentally incorrect.
Petrol is 16% hydrogen by mass, it's the marriage with carbon to form a room temperature liquid that is giving petrol its very high volumetric energy density.
Remove the carbon and now it becomes necessary to liquify the hydrogen by cryogenic means, or alternatively, increase the volumetric energy density by extreme pressurisation.
At 700 bar/10,000 psi, the effective volumetric energy density of gaseous hydrogen is about 10 times lower than petrol.
'Effective' meaning that once you include the required thickness of the storage tank walls to contain that pressure, and their cylindrical shape, compared to a petrol tank, the packaging volume required in a vehicle, vessel or aircraft is about 10 times higher for the same amount of energy stored.
Above 700 bar, the gas stops behaving like a compressible substance, so no amount of pressure increase above that is going to help very much, whilst at the same time making the stress situation in the tank walls considerably worse.
Apologies for OT post, but thought it somewhat relevant to cars as well.

[Lawts0908]

Fascinating. Many thanks for that, much appreciated.