Freelander 1 Overfueling

Nodge68 said:

The volume of air in the cylinders changes with engine speed anyway DD. Even before the turbo is taken into consideration. Air has a mass and like water flowing through a pipe, can only get so much into the cylinder in the operating cycle. So if you were to turn an engine slowly by hand. The cylinder would indeed fill with say 500cc of air. However spin that engine over at 4000 Rpm and suddenly 500cc of air can't get into the cylinder as the ports, valves, guides and other restrictions prevent it. So the cylinder ends up with only 450cc of air in the cylinder. This difference is called the Volumetric Efficiency or VE. Turbocharging actually forces air into the cylinders over and above the static volume. So the same 500cc cylinder can receive 600 or more ccs of air. This makes a huge difference to the torque an engine can produce at times of boost. So the engine design can be optimised for off boost torque production, with the boosted air improving high Rpm torque ability.

The MAF is used to tell the ECU how much air is in the cylinders, so the correct amount of fuel is added. Keeping in mind that black smoke production must be kept in check.

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What do you do for a living Nodge?

wammers said:

What do you do for a living Nodge?

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Retired from automotive engineering.

It's like talking to a brick wall.

Nodge68 said:

Retired from automotive engineering.

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What sort of lawnmower engines did you work on?

Gloves are off

wammers said:

What sort of lawnmower engines did you work on?

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Lawnmowers were a bit low tech for me, but I would be able to make them faster . I used to build performance vehicles for various client's. Mostly wolf's in sheep's clothing type stuff. Triumph straight six's were my favourite creations.
Here's one I did in 2003.

Lets cut the rubbish out here.

The driver tells the ECU how much fuel he wants to use. The MAF, combine with other sensors such as MAP, IAT and engine speed, tells the ECU how much is allowable to be injected.

The ECU will override the drivers wish with the values from the sensors - so the sensors, including MAF, are controlling the amount of fuel injected.

To see how much difference the MAF can make, this is a map from the EDC15 used in a 1.9 VAG engine. The EDC15 is used on Freelander TD4 but I haven't come across a mapping for that. The TD4 being slightly larger, probably using a different turbo charger, tuned at factory for different power requirement and of course simply being a different engine will have different values, but it gives an idea. It shows that as revs rise above idle, full boost detected by the MAF will allow roughly 50% more fuel into the cylinders (effectively turning the 2.0L into a 3.0L in "swept volume" terms discussed previously)

As said above, it will also be applying other limits. It will also be governing the EGR to allow these limits. Interestingly, and I forget where I got this info, the EDC15 does not use oxygen sensors in the exhaust, therefore it can not check that the sensors it is using are working within their original tolerances - therefore when MAFs go wrong (as the Bosch unit in TD4 does regularly!) you get black smoke (because its allowing to much fuel into the engine) rather than a MIL light lit!

Like it

I think the moderators should confine crusaders to a restricted thread category - can you image Wammers versus Joe on how overfueling a VCU causes high blood pressure on the nut on the end of the steering column if a 50mm lift is retrofitted to a dodgy MAF.
I'll get me coat

It shows that as revs rise above idle, full boost detected by the MAP will allow roughly 50% more fuel into the cylinders (effectively turning the 2.0L into a 3.0L in "swept volume" terms discussed previously)
Fixed that for you.

Nodge68 said:

Lawnmowers were a bit low tech for me, but I would be able to make them faster . I used to build performance vehicles for various client's. Mostly wolf's in sheep's clothing type stuff. Triumph straight six's were my favourite creations.
Here's one I did in 2003.
View attachment 109377

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Indeed pretty simple motor. When the 2.5 Pi came out they used to wear away the tag for the thrust bearing. Official factory cure was to drill an hole in the web and fit a self tapper. Some of the Stags and Dolomite sprints where abortions. Rover stuff P6 and 2000 were pretty good motors. British Leyland has a lot to answer for. The Marina, Allegro and Maxi were total crap. When you did a PDI on a four door Marina. You could almost guarantee the N/S rear door would not open. .

wammers said:

It shows that as revs rise above idle, full boost detected by the MAP will allow roughly 50% more fuel into the cylinders (effectively turning the 2.0L into a 3.0L in "swept volume" terms discussed previously)
Fixed that for you.

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It does nothing of the sort Wammers. That mapping is titled "Smoke map IQ limit by MAF".

I don't pretend to know exactly how the MAF is used in the fuel calculation, just going by the information available whether the MAF is used in calculating the amount of fuel to be injected. I have 1 voice saying it is not and all other references I see say it is. If you can show us somewhere that says it isn't, then maybe you won't be the lone voice.

I can think of a few reasons why it could/should be used.

GrumpyGel said:

It does nothing of the sort Wammers. That mapping is titled "Smoke map IQ limit by MAF".

I don't pretend to know exactly how the MAF is used in the fuel calculation, just going by the information available whether the MAF is used in calculating the amount of fuel to be injected. I have 1 voice saying it is not and all other references I see say it is. If you can show us somewhere that says it isn't, then maybe you won't be the lone voice.

I can think of a few reasons why it could/should be used.

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The MAP sensor. "MANIFOLD ABSOLUTE PRESSURE" sensor. Measures the turbo boost for fuelling. Little to do with MAF, although it,s flow reading maybe used by the ECU as cross reference, to ensure the MAP reading is sensible before injecting fuel to achieve a driver throttle power demand. The interlinking of the circuits and sensors on the later Emissions control systems is such that a glitch will cause some very strange behaviour. .

wammers said:

The MAP sensor. "MANIFOLD ABSOLUTE PRESSURE" sensor. Measures the turbo boost for fuelling. Little to do with MAF, although it,s flow reading maybe used by the ECU as cross reference, to ensure the MAP reading is sensible before injecting fuel to achieve a driver throttle power demand. The interlinking of the circuits and sensors on the later Emissions control systems is such that a glitch will cause some very strange behaviour. .

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You are being confused by the ECU fuel MAPS and the MAP sensor. I really do know what i am talking about honest.

GrumpyGel said:

It does nothing of the sort Wammers. That mapping is titled "Smoke map IQ limit by MAF".

I don't pretend to know exactly how the MAF is used in the fuel calculation, just going by the information available whether the MAF is used in calculating the amount of fuel to be injected. I have 1 voice saying it is not and all other references I see say it is. If you can show us somewhere that says it isn't, then maybe you won't be the lone voice.

I can think of a few reasons why it could/should be used.

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Older engines will use either Mass Air Flow (MAF) or MAP sensors to determine fueling (amongst other things). These days it is common to use both as MAP works better at low manifold pressures (less air flow) and MAF for higher air flows, at least in throttle controlled engines.

And speaking of throttle control, it has been quite common for diesels. The venable Fordson Tractors and Thames Trader trucks used Simms mechanical injector pumps. These used Manifold Air Pressure to determine fuel metering with the accelerator pedal connected to a throttle in the intake manifold.

Tony Reeves said:

Older engines will use either Mass Air Flow (MAF) or MAP sensors to determine fueling (amongst other things). These days it is common to use both as MAP works better at low manifold pressures (less air flow) and MAF for higher air flows, at least in throttle controlled engines.

And speaking of throttle control, it has been quite common for diesels. The venable Fordson Tractors and Thames Trader trucks used Simms mechanical injector pumps. These used Manifold Air Pressure to determine fuel metering with the accelerator pedal connected to a throttle in the intake manifold.

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Great fun if you derestricted the airflow, gave much more power and speed !!

The MAP sensor is better at lower revs and the MAF sensor at higher revs. What a complete and utter load of bollocks. You really don't have a clue what you are talking about.

wammers said:

You are being confused by the ECU fuel MAPS and the MAP sensor. I really do know what i am talking about honest.

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wammers said:

You really don't have a clue what you are talking about.

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I'm sure you basically know what you're talking about Wammers.

I'm also sure I know enough to know the difference between MAF sensor, MAP sensor and Fuel Maps.

I'm also sure that others are not as thick as you make them out to be.

One last thing I'm sure on.... is that you are wrong and that you know it - sorry that's 2 things.

We don't delete the MAF via the file service, the MAF is very important. Here's a quick explanation of why MAF delete is bad:

- MAF - Fuel economy: The MAF has both an air mass meter and an intake temperature sensor. The ECU makes small injection timing corrections based on the intake air temperature and the air mass flow. These result in both better fuel economy and also a smoother sounding engine.

- MAF - AFR calculation and smoke limitation: The main job of the MAF is to monitor how much air is available to enable the ECU to precisely control the fuel quantity injected in to the engine. If a MAF is deleted, we need to set some default high values so that power is not limited. This results in lots of smoke under full load as the car no longer controls Air Fuel Ratio (AFR), once the turbo spools up then there will be sufficient air and the car will run cleanly.

Off a reputable tuners website

That's in response to a question from someone that thinks the maf doesn't control fueling. Have you been sending emails Wammers?