Diesel Do said:
Think I've posted that before. Was told it was wrong:D
Click to expand...
Is it wrong though, or just doesn't fit a particular train of thought? :)

I'm working simpleton terms here.... The driver tells the engine how fast he wants the car to travel by how far he presses the loud peddle. The ECU sees this, and if the driver has shouted VERY LOUD, the ECU will convert that to LOTS OF FUEL. However, to ensure the driver is not wasting fuel out the exhaust pipe and because the bureaucrats in Brussels say that any demands the driver makes are going to kill the planet - the ECU puts lots of checks and balances into the loudness to fuel equation to make sure the levels of fuel used are brought down to a tree hugging and credit card acceptable level. So there is 1 sensor (the TPS) that governs the "Maximum" amount of fuel to inject - all the other sensors (MAF included) just impose a limiting value and may bring this level down.

Sounds to me as if the MAF controls the amount of fuel - but then as said, I'm only a simpleton.
 
Alibro said:
OK, for the benefit of the OP and me.
OP is getting black smoke on acceleration and someone suggested MAF.
OP disconnects the MAF and gets the same issue.
I suggested that means the MAF could well be at fault. My thinking was if the MAF was working correctly it would prevent the issue.
All hell then breaks loose and we get conflicting descriptions for how the MAF works.

So can a faulty MAF cause the car to belch out black smoke or not? And if it still belches out black smoke with the MAF disconnected what does this mean?
Click to expand...

Black smoke under full power is acceptable. So unless it's making an invisible smoke screen. I would just check out the live data.
It could be the EGR stuck open or a leaking boost pipe too.
 
Alibro said:
OK, for the benefit of the OP and me.
OP is getting black smoke on acceleration and someone suggested MAF.
OP disconnects the MAF and gets the same issue.
I suggested that means the MAF could well be at fault. My thinking was if the MAF was working correctly it would prevent the issue.
All hell then breaks loose and we get conflicting descriptions for how the MAF works.

So can a faulty MAF cause the car to belch out black smoke or not? And if it still belches out black smoke with the MAF disconnected what does this mean?
Click to expand...
Wrong type of snow?

The person he bought it off says its got the BMW engine, but he's actually driving an L Series?

Sorry can't help, just passing time till someone can give a definitive answer.
 
GrumpyGel said:
Is it wrong though, or just doesn't fit a particular train of thought? :)

I'm working simpleton terms here.... The driver tells the engine how fast he wants the car to travel by how far he presses the loud peddle. The ECU sees this, and if the driver has shouted VERY LOUD, the ECU will convert that to LOTS OF FUEL. However, to ensure the driver is not wasting fuel out the exhaust pipe and because the bureaucrats in Brussels say that any demands the driver makes are going to kill the planet - the ECU puts lots of checks and balances into the loudness to fuel equation to make sure the levels of fuel used are brought down to a tree hugging and credit card acceptable level. So there is 1 sensor (the TPS) that governs the "Maximum" amount of fuel to inject - all the other sensors (MAF included) just impose a limiting value and may bring this level down.

Sounds to me as if the MAF controls the amount of fuel - but then as said, I'm only a simpleton.
Click to expand...

Fuelling is not subject to air flow through the MAF other than as described earlier. But EURO level three emissions standards do as you say mean the fuelling is controlled to a far finer degree.
 
Nodge68 said:
Black smoke under full power is acceptable. So unless it's making an invisible smoke screen. I would just check out the live data.
It could be the EGR stuck open or a leaking boost pipe too.
Click to expand...

Could be the MAP sensor reading to much boost.
 
Diesel Do said:
I think I've said enough. I think you need to do a bit of homework on how things have changed. Older systems yes I agree with you but things have changed.
Click to expand...

Things have changed i am well aware of that, mainly in the way they are controlled to meet emission standards. But diesel engines still work the way they always have. Air in a cylinder fuel injected and bang. More fuel into same air bigger bang and so on and so forth. There is always more air than is needed for combustion. Turbo engines are no different. Common rail engines are no different. The idea that fuel quantity is controlled by the airflow through a MAF sensor is ridiculous. The power demand is the only thing that controls how much fuel is needed for any given throttle or power request. At idle the fuel air ratio maybe well over 100 to 1, so there is far more air being ingested than is needed, how can the flow through the MAF be controlling how much fuel is needed to maintain idle speed. Same story as fuel is increased up to boost starting to come in. There is always more air than needed. The amount of airflow through the MAF is irrelevant. True that if anyone of a number of sensors fail it can give problems that is down to how they are interlinked and read by the ECU. The Level three and upwards emission control systems are very complicated. But the idea that the MAF works the same way on diesels as it does on petrol engines is ridiculous. It just cannot be it is not possible.
 
I'm saying you clearly aren't interested in anything other than your opinion. You won't listen. You won't take on board any evidence presented to you. So based on that its pointless arguing with you. Land Rover themselves can tell you you're wrong and you wouldn't accept it. We've both been here before as have many others. It's pointless. You're happy in your world with your old fashioned diesels where you're quite right. But whether you like it or not things have moved on. I'm not going to explain it again as you really aren't interested. Go back and read the posts and links. They aren't fabricated to wind you up. It's documented fact.
 
Diesel Do said:
I'm saying you clearly aren't interested in anything other than your opinion. You won't listen. You won't take on board any evidence presented to you. So based on that its pointless arguing with you. Land Rover themselves can tell you you're wrong and you wouldn't accept it. We've both been here before as have many others. It's pointless. You're happy in your world with your old fashioned diesels where you're quite right. But whether you like it or not things have moved on. I'm not going to explain it again as you really aren't interested. Go back and read the posts and links. They aren't fabricated to wind you up. It's documented fact.
Click to expand...

Fuelling for a diesel engine is NOT controlled subject to airflow through the MAF sensor. Certain aspects of emission control are but NOT normal running fuelling. For any throttle demand, manifold pressure, RPM, air is constant. Only fuelling is changed to increase or decrease power. On a petrol engine the air is throttled, the amount of air entering the engine is controlled. The ECU then injects fuel to maintain a set mixture ratio of around 14 to 1. So the air flow readings from the MAF sensor are used to control fuelling. On a diesel that does not happen. A diesel engine always has a full cylinder of charge. Whether it be clean air or a mix of combustible air and exhaust gas with EGR operating. Without that full cylinder of charge little heat would be generated on compression and burn could not take place. For a diesel to run a full charge MUST exist at all times. On a none turbo diesel with say a swept volume of 500 cc there is always that amount of charge in the cylinder. From tick over to flat out ONLY the injected fuel changes the engine speed and power. Air is constant. A modern diesel is no different. It may have a very sophisticated emission control system that from time to time interferes with it, but it runs in exactly the same way as every other diesel.
 
The basic functionality no one is arguing. But on more modern engine it has far more input. No it's not the main sensor like on a petrol no one has said that. That's your argument to try and prove a point. You aren't interested in a new concept to you. You won't read anything that's posted. Even Flippin rave you say is wrong. It keeps on coming up. You always argue it. But there are so many questioning your argument doesn't it make you think? Hmmm maybe it does more than I think. But it's too late now you can't go back.
 
wammers said:
A diesel engine always has a full cylinder of charge. Whether it be clean air or a mix of combustible air and exhaust gas with EGR operating. Without that full cylinder of charge little heat would be generated on compression and burn could not take place. For a diesel to run a full charge MUST exist at all times. On a none turbo diesel with say a swept volume of 500 cc there is always that amount of charge in the cylinder. From tick over to flat out ONLY the injected fuel changes the engine speed and power. Air is constant. A modern diesel is no different. It may have a very sophisticated emission control system that from time to time interferes with it, but it runs in exactly the same way as every other diesel.
Click to expand...

This statement is incorrect. A non turbo engines swept volume is very different from static to flat out. It's ability to fill the cylinders is completely based on many factors. This is known as the engine's Volumetric Efficiency (VE). So in simple terms an engine of 500cc static volume won't fill the cylinders with 500cc of air when turning at 4700 Rpm. So the fuelling must to compensated to take this into account.

The MAF sensor on a modern diesel is as important for fueling as any other sensor on the engine. Things have moved on ;)
 
Diesel Do said:
The basic functionality no one is arguing. But on more modern engine it has far more input. No it's not the main sensor like on a petrol no one has said that. That's your argument to try and prove a point. You aren't interested in a new concept to you. You won't read anything that's posted. Even Flippin rave you say is wrong. It keeps on coming up. You always argue it. But there are so many questioning your argument doesn't it make you think? Hmmm maybe it does more than I think. But it's too late now you can't go back.
Click to expand...

I know what it does, yes it has more input on the EU 3 than it did on the EU2. But basically if a throttle demand is made under EU3 emission control the ECU looks for suitable airflow to see if that demand is feasible. If it sees sufficient airflow then that demand is actioned, if not it isn't. It simply does not work in the same way as a petrol MAF for control of normal fuelling as many believe.
 
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