Mystery freelander TD4 idle issue

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Nodge68 said:
Don't hurt your head ingesting duff information Gary.
The description of a diesel above is at least 15 years out of date.
Some elements are correct however the terminology used isn't. For starters a diesel isn't throttled, it's fueled. A diesel is a mixture controlled torque generator. Additional fuel injected above idle, doesn't necessarily increase speed. This additional fuel increases the engine's torque. Now if the increased torque output exceeds the load imposed, the engine will accelerate. If however the load and torque are in equilibrium, the engine will maintain it's speed. If the load exceeds the current torque, the engine slows down.
The thing with modern diesels is to keep burning the fuel cleanly. To do this, the driver selects a particular torque requirement, via the accelerator pedal. This then signals the ECU that more torque is needed. The ECU then adds more fuel. However the ECU has a set of rules to follow. One of those is to limit black smoke production. So the ECU monitors the mass of the air going in to intake. It then adds only enough fuel that can burn cleanly in the available air.
Gone are the days of black smoke and particulates coming out of the exhaust.
Click to expand...

am getting there , a lot to digest , lol

understanding more as I go along , ref torque etc, ie by having weight and the amount of torque required to move due to that

ecu parameters as set values and ie how chipped ecus change these set values

pedal and position via drive by wire as the amount of movement is sensed and tells the ecu what percentage it's at

ecu is the main brain and sensors are telling the ecu what all the measurements are around the engine

I think older deisel were timed to release fuel, where's as the modern one is a pressurised pump up to 25,000 psi , solonoids on the end of the injectors are opening and closing thousands of times , being told by the ecu according to the sensors feedback , adjusting the amount of fuel

by increasing the pressure will allow the fuel to atomise better Into smaller droplets , changing that according to temperature and outside ambient delta T differential

Including thermistors that tell the ecu what the different resistance readings are according to there temperatures

I think :D
 
Nodge68 said:
Don't hurt your head ingesting duff information Gary.
The description of a diesel above is at least 15 years out of date.
Some elements are correct however the terminology used isn't. For starters a diesel isn't throttled, it's fueled. A diesel is a mixture controlled torque generator. Additional fuel injected above idle, doesn't necessarily increase speed. This additional fuel increases the engine's torque. Now if the increased torque output exceeds the load imposed, the engine will accelerate. If however the load and torque are in equilibrium, the engine will maintain it's speed. If the load exceeds the current torque, the engine slows down.
The thing with modern diesels is to keep burning the fuel cleanly. To do this, the driver selects a particular torque requirement, via the accelerator pedal. This then signals the ECU that more torque is needed. The ECU then adds more fuel. However the ECU has a set of rules to follow. One of those is to limit black smoke production. So the ECU monitors the mass of the air going in to intake. It then adds only enough fuel that can burn cleanly in the available air.
Gone are the days of black smoke and particulates coming out of the exhaust.
Click to expand...
Don't waste your time Nodge, or Gary, this idiot @wammers is purely trolling - nothing more - all you are doing is feeding it. Simply ignore or preferably REPORT his posts. He has ruined a perfectly good accurate and informative thread. It is a shame.
 
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wammers said:
In particular that quoted above. Diesels are throttled by fuel, the more that is injected the faster they run. Air for any given manifold pressure is constant. Only the fuelling changes to increase the engine speed and power output. What part of "There is ALWAYS more air in the cylinder than is needed for combustion", do you not understand?
Click to expand...

as the engine runs in combustion wouldn't the air pressure change , as the Pistons move up and down and air compresses and doesn't compress through the 4 cycles of combustion

if the air was constant at the manifold would it need butterfly valves there. like a pump keeps air at a constant pressure up to the inlet manifold and then opens the butterfly valves but surely wouldn't the air pressure then drop , as if the pressure in the engine was greater than the inlet manifold it wouldn't be equal and act like a Venturi

hope that makes sense or I'm barking up the wrong tree

know it's a very complicated subject and know it takes many years
 
gstuart said:
am getting there , a lot to digest , lol

understanding more as I go along , ref torque etc, ie by having weight and the amount of torque required to move due to that

ecu parameters as set values and ie how chipped ecus change these set values

pedal and position via drive by wire as the amount of movement is sensed and tells the ecu what percentage it's at

ecu is the main brain and sensors are telling the ecu what all the measurements are around the engine

I think older deisel were timed to release fuel, where's as the modern one is a pressurised pump up to 25,000 psi , solonoids on the end of the injectors are opening and closing thousands of times , being told by the ecu according to the sensors feedback , adjusting the amount of fuel

by increasing the pressure will allow the fuel to atomise better Into smaller droplets , changing that according to temperature and outside ambient delta T differential

Including thermistors that tell the ecu what the different resistance readings are according to there temperatures

I think :D
Click to expand...
Hi Gary, just to confuse issues, many older diesels (Millions of them) used purely manifold vacuum (depression) via a venturi and butterfly valve to control engine injection via the fuel pump. This is termed a pneumatic governor.
There were many simple systems in between - more complex than the pneumatic governor and working towards today's types.
Most modern ones use direct closed loop air metering via MAF as the primary ecu sensor to control fuel injection. - that control of injection is usually via injector opening time control (duration), injection pressure control and also point of injection commencement.
It is all good fun.:) There is a lot of excellent technical info in this thread if you ignore the troll.
 
gstuart said:
as the engine runs in combustion wouldn't the air pressure change , as the Pistons move up and down and air compresses and doesn't compress through the 4 cycles of combustion

if the air was constant at the manifold would it need butterfly valves there. like a pump keeps air at a constant pressure up to the inlet manifold and then opens the butterfly valves but surely wouldn't the air pressure then drop , as if the pressure in the engine was greater than the inlet manifold it wouldn't be equal and act like a Venturi

hope that makes sense or I'm barking up the wrong tree

know it's a very complicated subject and know it takes many years
Click to expand...
On a modern diesel the air introduction path is always open so no actual pressure drop occurs, it is simply the measurement of air mass via the MAF and demand sensors (fbw accelerator position and delta (rate of change) and rpm)sensors that signal the ecu which after calculations and look ups signal when and how much to inject - the injection control itself is adjusted by the ecu controlling the pressure, injection duration and commencement of injection.

As said, many diesels from not too long ago were indeed manifold vacuum / depression controlled for fuel metering. :)
 
gstuart said:
as the engine runs in combustion wouldn't the air pressure change , as the Pistons move up and down and air compresses and doesn't compress through the 4 cycles of combustion

if the air was constant at the manifold would it need butterfly valves there. like a pump keeps air at a constant pressure up to the inlet manifold and then opens the butterfly valves but surely wouldn't the air pressure then drop , as if the pressure in the engine was greater than the inlet manifold it wouldn't be equal and act like a Venturi

hope that makes sense or I'm barking up the wrong tree

know it's a very complicated subject and know it takes many years
Click to expand...

Only the cylinder on induction with the inlet valve open receives a charge of air. The other cylinders are either firing exhausting or compressing.
 
wammers said:
Sport.
Click to expand...

The RR sport you are referring to was a monocoque on a chassis. This was done to simplify the production process at the time. It is now a 15 year old design. The production process has since been completely redesigned.
All current LR models are monocoque, except for the D4. That will change when the D5 is released as that will be a monocoque too.
Nothing wrong with my LR information. Yours is 15 years out of date however :mad:
 
Nodge68 said:
The RR sport you are referring to was a monocoque on a chassis. This was done to simplify the production process at the time. It is now a 15 year old design. The production process has since been completely redesigned.
All current LR models are monocoque, except for the D4. That will change when the D5 is released as that will be a monocoque too.
Nothing wrong with my LR information. Yours is 15 years out of date however :mad:
Click to expand...

Took you along time to Google that. :p
 
Gary think of the diesel engine as an oil fired boiler. That is a simple heat generator, whereas a diesel is a torque generator.
Now an oil fired boiler can generate as much heat (it's equivalent to torque) simply by adding more oil. This could be by using a larger nozzle or increase pump pressure. However there has to be an increase in air, or it'll smoke. So you open the air flap to increase the O2 available to match the higher oil supply rate.
That's basically the theory of the diesel, but massively simplified. The diesel has fully open air all the time. Only the quality of fuel is changed, to increase output. ;)
 
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Nodge68 said:
Gary think of the diesel engine as an oil fired boiler. That is a simple heat generator, whereas a diesel is a torque generator.
Now an oil fired boiler can generate as much heat (it's equivalent to torque) simply by adding more oil. This could be by using a larger nozzle or increase pump pressure. However there has to be an increase in air, or it'll smoke. So you open the air flap to increase the O2 available to match the higher oil supply rate.
That's basically the theory of the diesel, but massively simplified. The diesel has fully open air all the time. Only the quality of fuel is changed, to increase output. ;)
Click to expand...

Oh at last you understand.
 
I don't care what he does as long as intelligent discussion and dissemination of information like this takes place. I've got a lot from this thread if only to put in place and correctly inter-relate the info I had already. Keep it up, chaps. Sometimes the trolls are self-feeding and there's nothing you can do except ignore them. Thanks.
 
DevonGuy said:
I don't care what he does as long as intelligent discussion and dissemination of information like this takes place. I've got a lot from this thread if only to put in place and correctly inter-relate the info I had already. Keep it up, chaps. Sometimes the trolls are self-feeding and there's nothing you can do except ignore them. Thanks.
Click to expand...

also learnt a considerable amount from this thread , lol
 
Nodge68 said:
Gary think of the diesel engine as an oil fired boiler. That is a simple heat generator, whereas a diesel is a torque generator.
Now an oil fired boiler can generate as much heat (it's equivalent to torque) simply by adding more oil. This could be by using a larger nozzle or increase pump pressure. However there has to be an increase in air, or it'll smoke. So you open the air flap to increase the O2 available to match the higher oil supply rate.
That's basically the theory of the diesel, but massively simplified. The diesel has fully open air all the time. Only the quality of fuel is changed, to increase output. ;)
Click to expand...

now that I can follow :D:D

cheers mate , when I started working on oil boilers it taught me a considerable amount in how combustion worked , when I done some boilers that were installed outside was able to pull the burner and fire it up , kept me warm whilst working on the boiler in the winter

also by adjusting the pressure and air could see how the flame changed and how and what affected it

was also very good in teaching the apprentices

surprising when boilers were over aired they really started to smell ,
 
Joe_H said:
lol - but sadly wasted - as per our troll...... :D (he will be googling frantically now)
ROFLMAO :p
Click to expand...

If i ever want to know how to apply a plaster i'll ask you. You are not qualified to answer anything else. Unlike you no need to Google on matters mechanical.
 
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