Disco 2 Td5 maf

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wtf its happened again! :confused::confused::rolleyes:o_O haha

So basically one way if no EGR MAF does nothing the other way the MAF does something regardless of EGR.

I only ask as my 110 behaves the same way with the MAF connected or not!
 
Hi Bankz,

For your motor, why not ask Jose the tuner , only he will know exactly what the MAF connected or not connected will achieve on his tuning map.

Cheers
 
wammers said:
...... more fuel faster, less fuel slower, air is constant for any given engine speed manifold pressure.
Click to expand...
And i'll say it too for the very last time...the amount of fuel delivered into a chamber with constant air in it is managed by that dumb ECU through the injectors and that ECU was built(by those who dont have a clue) to calculate that IQ based on MAF readings too... it's an electronic processor which will do what was built to do even if it's wrong and it doesnt care about your theory(which i dont contest)... that's why over or under fuelling can occur when a part of the management doesnt work well cos the ECU will do what it was programmed to do based on the sensor's inputs... and it's not human to be ''confused" :cool:
 
I did! He said it won't really make any difference. You can buy a 'boost box' for the MAF which allows it to read higher boost properly without being upset, though all it does it bring max torque in about 90rpm sooner which is minimal. Plugged in it just gets a bit flat at the top end.

Was just trying to learn more about what the MAF sensor actually governs really, plus its easier to have a discussion on here with many folk than one person :)
 
To see what's about your MAF a live data log is needed, as long as they interviened into the fuel map only they know what it will do so if they altered the fuel map as to be neglected you can drive without it rather than clamp it... the ECU will do with the MAF input what they programmed it to do with it but dont expect a tuner to explain you with details
as about the following
bankz5152 said:
You can buy a 'boost box' for the MAF which allows it to read higher boost properly without being upset,
Click to expand...
IMO it's the same as any bodge or external bypass, completely incorrect way to do things ... also the MAF doesnt read boost, it's readiing is dependant on boost cos the higher the boost is the higher the sucction through the MAF is that's why i said that if the MAP was recalibrated the MAF should have been recalibrated too as the ECU's ADC to convert the highest voltage reading as to not cut out at 680
 
sierrafery said:
To see what's about your MAF a live data log is needed, as long as they interviened into the fuel map only they know what it will do so if they altered the fuel map as to be neglected you can drive without it rather than clamp it... the ECU will do with the MAF input what they programmed it to do with it but dont expect a tuner to explain you with details
as about the following
IMO it's the same as any bodge or external bypass, completely incorrect way to do things ... also the MAF doesnt read boost, it's readiing is dependant on boost cos the higher the boost is the higher the sucction through the MAF is that's why i said that if the MAP was recalibrated the MAF should have been recalibrated too as the ECU's ADC to convert the highest voltage reading as to not cut out at 680
Click to expand...

I kinda follow... though the MAP isnt an LR unit its an uprated one from a VW I think, then the ECU was recalibrated to suit. Afaik there isnt an uprated MAF for the TD5, when I said "boost box" i didnt mean boost box i meant it as theres a device that plugs in between the MAF anf LR wiring that allows you to manually adjust the MAF sensor
 
I understood what you meant by boost box that's why i said better run with it unplugged rather than clamped ... you can try something else but i'm not sure how it will work, some tuners are using a so called "uprated MAF" which like the MAP they use is not something uprated for the Td5 but built for other vehicle with a diffrent reading curve, this is the one: http://www.ebay.com/itm/251174166371?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT , it fits perfectly and has different reading curve, i've tried one on my car without altering the fuel map for it and there was better throttle response in the midle range but i'm sure that my fuel map is different
 
sierrafery said:
And i'll say it too for the very last time...the amount of fuel delivered into a chamber with constant air in it is managed by that dumb ECU through the injectors and that ECU was built(by those who dont have a clue) to calculate that IQ based on MAF readings too... it's an electronic processor which will do what was built to do even if it's wrong and it doesnt care about your theory(which i dont contest)... that's why over or under fuelling can occur when a part of the management doesnt work well cos the ECU will do what it was programmed to do based on the sensor's inputs... and it's not human to be ''confused" :cool:
Click to expand...

Diesel engines, any diesel engine, even the one in your TD5 are fuelled subject to throttle demand/power request. Several sensors fine turn delivered fuel to meet those throttle demand power requests. Airflow through the MAF is not one of them. Diesel engines do not run at stoichiometric mixture ratios at any time other than that attempted when EGR is active. Running a stoichiometric mixture ratio at any other time is impossible on a diesel engine. Any stoichiometric mapping in the ECU will be used in conjunction with EGR and at no other time. You are not the expert you think you are.
 
I'm no expert at all in diesel engines i admit that but i am quite good with electronics and about the Td5's management i've learned from an expert, and the expert's statements after he reverse engineered the Td5 ECU are:

"For EU3 motors the data from the MAF sensor and the Engine Speed in RPM are used to determine the airmass in milligrams within each cylinder on each intake stroke (mg/stroke). As a backup EU3 motors will fail over to MAP/IAT based calculations if the MAF is outside a specific range .
The airmass figures indicates is the mass of air within the cylinder at the end of the intake stroke. This is a critical piece of information for the engine as the amount of fuel injected depends on a combination of the amount of air within the cylinder and the speed of the engine
....
The MAF airmass calculation is simplified because the MAF reading is already provides the airmass entering the engine given in kg/Hr. Conversion from kg/hr -> g/min is done by multiplying by 1000 and dividing by 60. The intake stroke of each cylinder occur once every 2 revolutions, so the airmass is divided by 5/2 to determine the amount per cylinder. The ECU code combines these to simplify calculation:

33.333 = (1000 * 2) / 60

The final code used in all variants of the Td5 ECU is:

airmass = (MAF * 33333) / (RPM * 5)

Note that the decimal point of the constant is shifted right three places to retain precision in integer math. The ECU representation of the MAF vale has it's decimal point shifted one place to the right. This is significant when reading the ECU maps as the map values use these fixed point numbers.

To confirm the magnitude of the units, lets apply this to the Nanocom values at a typical idle reading of 60kgHr/ 760rpm.

airmass(g) = 60 * 33.333 / 760 *5 airmass = 0.5263g or 526.3mg

And at 680kg/Hr/ 3500rpm airmass = 1.2952g or 1295.2mg

Referring to 0.5623g airmass feels pretty clumsy, so my preference is to use mg.
...........
"
that's a "flavour" from how the Td5 ECU was built to act and it does it with EGR or without cos it's the same for African export Td5's too which dont have EGR from factory but they have the MAF for the purpose explained above, that's a FACT regardless of your theory about how the ENGINE is throttled by fuel cos i'm speaking only about the electronic management which delivers that fuel... if you contradict what's with blue you will simply make a fool of yourself and you dont deserve that

we can continue a friendly debate on this for ages but we'll just repeat things we've already said and not reach a common conclusion cos you insist on how the engine works(which i dont contest) and i'm speaking strictly about the electronic management, IMO the guy who made that video about how to check the MAF is 100% correct when he sais that "MAF helps with the fuelling strategy".

and now i promise to not come back on this subject with you no matter what you say cos we become(or already became) subject of jokes for others :cool:
 
Last edited:
sierrafery said:
I'm no expert at all in diesel engines i admit that but i am quite good with electronics and about the Td5's management i've learned from an expert, and the expert's statements after he reverse engineered the Td5 ECU are:

"For EU3 motors the data from the MAF sensor and the Engine Speed in RPM are used to determine the airmass in milligrams within each cylinder on each intake stroke (mg/stroke). As a backup EU3 motors will fail over to MAP/IAT based calculations if the MAF is outside a specific range .
The airmass figures indicates is the mass of air within the cylinder at the end of the intake stroke. This is a critical piece of information for the engine as the amount of fuel injected depends on a combination of the amount of air within the cylinder and the speed of the engine
....
The MAF airmass calculation is simplified because the MAF reading is already provides the airmass entering the engine given in kg/Hr. Conversion from kg/hr -> g/min is done by multiplying by 1000 and dividing by 60. The intake stroke of each cylinder occur once every 2 revolutions, so the airmass is divided by 5/2 to determine the amount per cylinder. The ECU code combines these to simplify calculation:

33.333 = (1000 * 2) / 60

The final code used in all variants of the Td5 ECU is:

airmass = (MAF * 33333) / (RPM * 5)

Note that the decimal point of the constant is shifted right three places to retain precision in integer math. The ECU representation of the MAF vale has it's decimal point shifted one place to the right. This is significant when reading the ECU maps as the map values use these fixed point numbers.

To confirm the magnitude of the units, lets apply this to the Nanocom values at a typical idle reading of 60kgHr/ 760rpm.

airmass(g) = 60 * 33.333 / 760 *5 airmass = 0.5263g or 526.3mg

And at 680kg/Hr/ 3500rpm airmass = 1.2952g or 1295.2mg

Referring to 0.5623g airmass feels pretty clumsy, so my preference is to use mg.
...........
"
that's a "flavour" from how the Td5 ECU was built to act and it does it with EGR or without cos it's the same for African export Td5's too which dont have EGR from factory but they have the MAF for the purpose explained above, that's a FACT regardless of your theory about how the ENGINE is throttled by fuel cos i'm speaking only about the electronic management which delivers that fuel... if you contradict what's with blue you will simply make a fool of yourself and you dont deserve that

we can continue a friendly debate on this for ages but we'll just repeat things we've already said and not reach a common conclusion cos you insist on how the engine works(which i dont contest) and i'm speaking strictly about the electronic management, IMO the guy who made that video about how to check the MAF is 100% correct when he sais that "MAF helps with the fuelling strategy".

and now i promise to not come back on this subject with you no matter what you say cos we become(or aready became) subject of jokes for others :cool:
Click to expand...

Fuel is injected to satisfy the RPM/power demand requested. It has nothing to do with airflow through the MAF sensor. The MAF sensor measures the amount of exhaust gas being ingested when EGR is in operation by showing a reduced air flow. The ECU then modulates the EGR valve to give best combustible air to fuel ratio to reduce Nox production. At no time does the fuelling needed to produce the requested engine RPM change. Only the cylinders combustible air quantity changes. How the engine is throttled and fuelled is a fact not a theory. OK truce declared. ;)
 
I thought the MAF's main purpose was for LIMITING the fuel so as to not cause a smokey engine (as in it just makes sure the fuel cannot go over the max air:fuel ratio and being diesel, this is a massive band that it can operate in). Also for the EGR control and in some cases for calculating how much fuel to dump in the engine? (although yes, depending on the vehicle and customization, this can normally be run off the MAP sensors)

Then again, I'm used to VW PD engines where this is more the case, thought it was pretty much the same here?
 
Simon098 said:
I thought the MAF's main purpose was for LIMITING the fuel so as to not cause a smokey engine (as in it just makes sure the fuel cannot go over the max air:fuel ratio). Also for the EGR control and in some cases for calculating how much fuel to dump in the engine? (although yes, depending on the vehicle and customization, this can normally be run off the MAP sensors)

Then again, I'm used to VW PD engines where this is more the case, thought it was pretty much the same here?
Click to expand...

Oh dear. It is when EGR is active. It's signals are used to measure ingested exhaust gas and the ECU modulates the EGR valve to maintain combustible air ratio subject to fuel needed for the present requested throttle/power demand. If an higher throttle power demand is requested the ECU will not allow more fuel to be injected to service it until the airflow through the MAF increases as the EGR valve is closed or exhaust gas ingestion reduced to give enough combustible air content to service the extra fuel needed for the increased throttle demand. When EGR is not in operation, say on hard acceleration, the EGR is shut so there is always more air in the cylinder than is needed for combustion. The ECU then controls the amount of fuel injected subject to sensor signals within the pre written fuelling map for any given engine RPM manifold pressure engine load. Airflow through the MAF sensor is irrelevant.
 
wammers said:
Oh dear. It is when EGR is active. It's signals are used to measure ingested exhaust gas and the ECU modulates the EGR valve to maintain combustible air ratio subject to fuel needed for the present requested throttle/power demand. If an higher throttle power demand is requested the ECU will not allow more fuel to be injected to service it until the airflow through the MAF increases as the EGR valve is closed or exhaust gas ingestion reduced to give enough combustible air content to service the extra fuel needed for the increased throttle demand. When EGR is not in operation, say on hard acceleration, the EGR is shut so there is always more air in the cylinder than is needed for combustion. The ECU then controls the amount of fuel injected subject to sensor signals within the pre written fuelling map for any given engine RPM manifold pressure engine load. Airflow through the MAF sensor is irrelevant.
Click to expand...

Again. I think you missed my point. I didn't say the MAF was used for fuel CONTROL. I said it's used as a smoke limiter (regardless of EGR control). Reason I say this and I'm only asking because I'm unsure for this ECU, is that the PD engines I'm used to working with DEFINATELY use the MAF as a SMOKE LIMITER, they also use it for EGR feedback like you keep mentioning though. Thanks for the sarcasm though, was only asking. ;)

So just to clarify, the driver can request WHATEVER it likes, so long as the SMOKE LIMIT is not exceeded.
 
Simon098 said:
Again. I think you missed my point. I didn't say the MAF was used for fuel CONTROL. I said it's used as a smoke limiter (regardless of EGR control). Reason I say this and I'm only asking because I'm unsure for this ECU, is that the PD engines I'm used to working with DEFINATELY use the MAF as a SMOKE LIMITER, they also use it for EGR feedback like you keep mentioning though. Thanks for the sarcasm though, was only asking. ;)

So just to clarify, the driver can request WHATEVER it likes, so long as the SMOKE LIMIT is not exceeded.
Click to expand...

And i just explained it isn't, smoke limitation is down to the fuel map written into the ECU for any given throttle request power demand or engine load, it has nothing at all to do with the MAF sensor. How do you think ECU controlled diesel engines that don't have MAF sensor prevent smoke?
 
Hi getting back to the problem td5 running badly I think from reading the posts it is not likely to be the MAF sensor making it run that badly, from problems I have had with mine I would start by looking at how it runs, does it tick over okay and does it run well up a point where it just runs out of steam, If this is the case I would think I would start by looking at fuel pump and then fuel pressure reg. When my pump went it lost top end and slowly got worse, it showed fault codes telling me i had problems with more than 1 injector.
If it runs badly all the time it might be a problem with cables between ECU and injector I had this and changed cables under rocker cover and all worked well,
Is EGR still connected, might be a good idea to try blocking it off, I blocked mine off and it seamed to run better and did not cost a lot
 
Simon098 said:
Again. ... I said it's used as a smoke limiter (regardless of EGR control). Reason I say this and I'm only asking because I'm unsure for this ECU, is that the PD engines I'm used to working with DEFINATELY use the MAF as a SMOKE LIMITER,
Click to expand...
You are right, here is how the Td5 ECU works for that: http://www.discotd5.com/ecu-reverse-engineering/smoke-limiter-maps , it uses the MAF/RPM inputs for the airmass(mg/stroke) calculation for smoke limiters and IQ on Eu3 engines which are the closest to VW PD engines than to any other in the world
 
Last edited:
Ian M in France said:
Hi getting back to the problem td5 running badly I think from reading the posts it is not likely to be the MAF sensor making it run that badly, from problems I have had with mine I would start by looking at how it runs, does it tick over okay and does it run well up a point where it just runs out of steam, If this is the case I would think I would start by looking at fuel pump and then fuel pressure reg. When my pump went it lost top end and slowly got worse, it showed fault codes telling me i had problems with more than 1 injector.
If it runs badly all the time it might be a problem with cables between ECU and injector I had this and changed cables under rocker cover and all worked well,
Is EGR still connected, might be a good idea to try blocking it off, I blocked mine off and it seamed to run better and did not cost a lot
Click to expand...

I had similar issues, turned out I had a sluggish pump and injector seals gone. Swapped pump and the injector seal issue showed up straight away, wasn't as obvious until I changed the pump.
 
sierrafery said:
I'm no expert at all in diesel engines i admit that but i am quite good with electronics and about the Td5's management i've learned from an expert, and the expert's statements after he reverse engineered the Td5 ECU are:

"For EU3 motors the data from the MAF sensor and the Engine Speed in RPM are used to determine the airmass in milligrams within each cylinder on each intake stroke (mg/stroke). As a backup EU3 motors will fail over to MAP/IAT based calculations if the MAF is outside a specific range .
The airmass figures indicates is the mass of air within the cylinder at the end of the intake stroke. This is a critical piece of information for the engine as the amount of fuel injected depends on a combination of the amount of air within the cylinder and the speed of the engine
....
The MAF airmass calculation is simplified because the MAF reading is already provides the airmass entering the engine given in kg/Hr. Conversion from kg/hr -> g/min is done by multiplying by 1000 and dividing by 60. The intake stroke of each cylinder occur once every 2 revolutions, so the airmass is divided by 5/2 to determine the amount per cylinder. The ECU code combines these to simplify calculation:

33.333 = (1000 * 2) / 60

The final code used in all variants of the Td5 ECU is:

airmass = (MAF * 33333) / (RPM * 5)

Note that the decimal point of the constant is shifted right three places to retain precision in integer math. The ECU representation of the MAF vale has it's decimal point shifted one place to the right. This is significant when reading the ECU maps as the map values use these fixed point numbers.

To confirm the magnitude of the units, lets apply this to the Nanocom values at a typical idle reading of 60kgHr/ 760rpm.

airmass(g) = 60 * 33.333 / 760 *5 airmass = 0.5263g or 526.3mg

And at 680kg/Hr/ 3500rpm airmass = 1.2952g or 1295.2mg

Referring to 0.5623g airmass feels pretty clumsy, so my preference is to use mg.
...........
"
that's a "flavour" from how the Td5 ECU was built to act and it does it with EGR or without cos it's the same for African export Td5's too which dont have EGR from factory but they have the MAF for the purpose explained above, that's a FACT regardless of your theory about how the ENGINE is throttled by fuel cos i'm speaking only about the electronic management which delivers that fuel... if you contradict what's with blue you will simply make a fool of yourself and you dont deserve that

we can continue a friendly debate on this for ages but we'll just repeat things we've already said and not reach a common conclusion cos you insist on how the engine works(which i dont contest) and i'm speaking strictly about the electronic management, IMO the guy who made that video about how to check the MAF is 100% correct when he sais that "MAF helps with the fuelling strategy".

and now i promise to not come back on this subject with you no matter what you say cos we become(or already became) subject of jokes for others :cool:
Click to expand...

The RPM is a result of injected fuel, the airflow a consequence of the RPM. You cannot take an airflow reading at any RPM then surmise that the fuel being injected is a result of that airflow. It isn't. The reverse engineering people have it the wrong way around. ;)
 
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