OT: Pinking Diesel Engine

[Cursitor Doom]

*Very* early designs. I'm giving my age away now. ;-)

[Dave Plowman (News)]

Albion were one that used direct injection for diesel engines long before WW2. Most usually four cylinder units for trucks.

[Cursitor Doom]

Yeah, like good advice 20 years ago. Today you pretty much have to go to someone who specialises in the particular engine and EMU so therefore has the hardware interfaces and software for that specific model.

[Cursitor Doom]

I was wondering that, too.

[Fredxxx]

Are you being deliberately stupid?

We don't know what pump he has, as I have seen on many occasions is a conventional pump with a drive by wire fuel control. The timing is done by the pump itself and can only be checked through conventional means.

Being a Landrover, it is more like to be old rather than new. Saying something out of the blue "Do you actually know how the injection timning works on a modern diesel?" is entirely irrelevant and insincere.

Assuming it has a sensor related to injection timing. In true form you are being very presumptuous.

[Cursitor Doom]

Good question. I've often wondered about that as well. :-/

[Fredxxx]

OK.

The only ones I have seen are into a hot bulb. I have never seen one you talk of.

Even this wiki article says the model airplane engine doesn't scale up.

[Chris]

Certainly is a lot closer to old than new! It's a 2003 TD5 (the TD5 is a BMW engine).

[The Natural Philosopher]

Well I wouldn't advocate 'measuring te timing in a modern petrol engine, either...

I believe they MAY have done on mecahnical injectors, but thats REALLY old school

I have a BMW diesel in a freelander, and that WILL start after a few cranks from cold, but with a lot of smoke. If I wait till the glowplug lights go out, it starts quicker with a lot less smoke.

[The Natural Philosopher]

Well yes, I think I am.

If restoring it to life is the aim.

[The Natural Philosopher]

Its called software and its in the ECU.

Look the whole point is simply this. ALL the timing depends on the software and the sensors. With a new EMU one may assume the software works. Ergo one or more sensors have probably not been reattached.Or are faulty

Its unlikely to be a failing crank sensor, as these tend to work, or not work, and if not working should throw an error code.

It COULD be an analogue sensor, like air temperature or airflow meter or somesuch, that isn't changing as it should but is still outsize 'fault parameters' when the ECU checks it.

WE don't even know if its a turbodiesel or not.

Lots more sensors on those.

[The Natural Philosopher]

I don't think that layout would *have* an 'EMU'

WEll I have had diesel landrovers for the last 20 years and non of them are as you describe. The old defneder 4 pot, then te TD4, aqnd tre BMW TD4 unit are all electronic.

Well yes, I am presuming that the OP and you are not so completely moronic as to check the sensor for the ABS, in an effort to resolve pinking in the diesel.

If that is an assumption too far, I apologise, but possibly, if you are that stupid, you shouldn't be allowed near a fuel injection system.

[Tim Lamb]

The injector pump had rotating weights which altered the injection point relative to engine speed or fuel quantity or both. Beyond my knowledge.

I once set the injector pump timing on an ancient David Brown tractor. The sort you see towing the bomb trolleys in WW2 RAF films. There were timing marks on the gear train and I think the pump had to be arranged for the fuel *spill* point to be a few deg. before TDC.

[news]

That's right, lorry and tractor engines tended to be direct injection but the rapid rise in pressure as the atomised fuel burnt gave them the harsh knock but it wasn't the same as pinking.

So passenger vehicles injected the spray into a swirl chamber (Ricardo invention I think) the partially burned fuel air mixture then exited into the cylinder to complete combustion and this meant the pressure rise was smoother. The drawback was that the combustion continued as the piston descended , so some of the heat expanded from a lower pressure, hence less thermodynamic efficiency.

Common rail with the higher pressure leads to finer fuel droplets and faster switching of the injectors than a piston pumping fuel past a injector poppet valve, so a short squirt at around TDC can initiate combustion and then the main charge is squirted in once a flame front has developed, giving a smoother pressure rise and complete combustion near the top of the stroke, moving the diesel cycle into the realms of the Otto cycle whilst keeping the volumetric efficiency of the diesel at part throttle. This still isn't as ideal as a constant volume combustion but the higher compression ratio and volumetric efficiency still give it the edge.

AJH

[Clive George]

Your XUD engine had little inserts in the cylinder head where the fuel injector and glowplugs go. They make a little chamber away from the piston head. Hence indirect. The injector on the HDi goes straight into the main chamber - direct.

A friend had a little rattling in a XUD which swiftly turned into a stopped engine - the insert in one of the cylinders had fallen out, and having the piston bash it against the head top leads to a big mess very quickly. I've not heard of that happening to anybody else though.

The fuel pressure on the direct injection one is way higher - at least

10x. Which means tinier droplets, which means easier to burn, which means easier to start - no need for the glow plugs.

[The Natural Philosopher]

Well you haven't attended many aeromodelling shows then.

And the video shows one being started and run, so its not fiction. I've owned half a dozen in my youth, and they are still being made today.

In fact I think that you CAN scale what you call 'hot bulb' (gloplug) engines up, and in fact a lot of diesels may or may not use the assistance of glow plugs even after they have started. I don't know. BUT (some of) the paraffin engines of yore are very much akin to scaled up 'gloplug' engines. although they tend to be 4-strokes.

Gas engines used hot ceramic gloplugs too.

All forms of ignition have been tried. What's left is what worked best in any given application

NO it doesn't.

[The Natural Philosopher]

The Td5 is NOT BMW though. It is Landrovers own.

That is new!

This is oLd

The old non boosted 2.5 litre 4 pot.

[Clive George]

That's a modern one isn't it? I count anything common rail as modern, and with a mechanical pump as the older tech. So my 2001 HDi is modern.

Says the TD5 is the only one of the time which isn't a BMW :-)

Unit injection (reads more). Ah, like PD. Not a mechanical pump, nor common rail - early electric. Direct injection though, and controlled electrically, ie timing comes from the computer.

[Vir Campestris]

Quite the reverse. The problem was they couldn't get it off the ship before it detonated.

Andy

[Chris]

That's odd. It has "Td5 BMW Power" embossed into its acoustic cover!

I see there was another version for the Discovery. Mine's the Defender so maybe they've replaced the EMU with the wrong type.