Mystery freelander TD4 idle issue

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Joe_H said:
No worries, click a huge like to my diagnosis and solution :) ;) and remember occams razor ....
You owe me several dozen pints - !!! - never go searching for the expensive stuff ! - consider the actual logical issue.
:D

Cheques by post please...:rolleyes:
Joe

(Never a word of thanks..................:()
Click to expand...

occams razor? sry but my English is not my mother language hehe
 
V8 Addict said:
occams razor? sry but my English is not my mother language hehe
Click to expand...
Sorry, I didn't realise English was not your first Language - search - in your native language for Occams Razor.

Basically - it implies that after all diagnosis , the most logical and simplest is the solution on most cases. As in here, the MAF measure the airflow into the engine (The MASS and Temperature- hence knowing the O2 content) .
The MAF is connected between the air intake and the turbo intake and is supposed to measure ALL air intake and adjust fuelling accordingly - WHEN a leak occurs - such as you had (The intake air BYPASSED the maf, then the MAF signals a lower air mass intake (hence O2) to the ECU and the fuelling is limited.
Because you replaced the maf it was logical that that was NOT the issue. Hence the most likely, simple and most logical explanation was an air intake LEAK after the MAF and BEFORE the turbo - as you found..
When you disconnect the MAF you go to a failsafe mapped setting ignoring the MAF - As this worked ok, you can then logically assume that ALL fuelling / pressure etc is absolutely fine and the issue is one of MAF bypass.

"In science, Occam's razor is used as a heuristic technique (discovery tool) to guide scientists in the development of theoretical models, rather than as an arbiter between published models.[1][2] In the scientific method, Occam's razor is not considered an irrefutable principle of logic or a scientific result; the preference for simplicity in the scientific method is based on the falsifiability criterion. For each accepted explanation of a phenomenon, there may be an extremely large, perhaps even incomprehensible, number of possible and more complex alternatives, because one can always burden failing explanations withad hoc hypotheses to prevent them from being falsified; therefore, simpler theories are preferable to more complex ones because they are moretestable.[3][4][5]"

Joe. and glad all sorted, our repair rates are free lol...
 
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blue beasty said:
Did someone mention cake?
Click to expand...
No !!! NEVER !!! - GO AWAY -- It is only a small c.... :D
Begger me, tis like a blood hound after a crumb.........:rolleyes:
Can you not buy a spray can for them BB's ???

Come to think of it - we will have Master Tech @wammers next telling us about how MAF units make no difference and it is only the fuel and other sh!te....:eek::oops::rolleyes::D

Ho Hum......

;)

Something about his knowledge not being able to fit on a postage stamp ? - or was it a pinhead ? (on his EGO wall / signature) LMFAO !!:D:D:D:D:D
 
Joe_H said:
Sorry, I didn't realise English was not your first Language - search - in your native language for Occams Razor.

Basically - it implies that after all diagnosis , the most logical and simplest is the solution on most cases. As in here, the MAF measure the airflow into the engine (The MASS and Temperature- hence knowing the O2 content) .
The MAF is connected between the air intake and the turbo intake and is supposed to measure ALL air intake and adjust fuelling accordingly - WHEN a leak occurs - such as you had (The intake air BYPASSED the maf, then the MAF signals a lower air mass intake (hence O2) to the ECU and the fuelling is limited.
Because you replaced the maf it was logical that that was NOT the issue. Hence the most likely, simple and most logical explanation was an air intake LEAK after the MAF and BEFORE the turbo - as you found..
When you disconnect the MAF you go to a failsafe mapped setting ignoring the MAF - As this worked ok, you can then logically assume that ALL fuelling / pressure etc is absolutely fine and the issue is one of MAF bypass.

"In science, Occam's razor is used as a heuristic technique (discovery tool) to guide scientists in the development of theoretical models, rather than as an arbiter between published models.[1][2] In the scientific method, Occam's razor is not considered an irrefutable principle of logic or a scientific result; the preference for simplicity in the scientific method is based on the falsifiability criterion. For each accepted explanation of a phenomenon, there may be an extremely large, perhaps even incomprehensible, number of possible and more complex alternatives, because one can always burden failing explanations withad hoc hypotheses to prevent them from being falsified; therefore, simpler theories are preferable to more complex ones because they are moretestable.[3][4][5]"

Joe. and glad all sorted, our repair rates are free lol...
Click to expand...

am not that technical with cars , but am fine with boilers , lol

after reading this a few times. it got me thinking , would the maf be something similar to a potentiometer, as was just trying to compare that with the way a maf works and this fault

but think I understand about the maf, due to it not getting the correct designed amount of air the maf goes into a default setting that is governed by the ecu as a way of a fail safe

so if the large turbo hose at the front was off it was getting far more air than it should do

hope that may make some sort of sense or am I barking up the wrong tree and miles off track

sorry being a bit dense , lol
 
gstuart said:
am not that technical with cars , but am fine with boilers , lol

after reading this a few times. it got me thinking , would the maf be something similar to a potentiometer, as was just trying to compare that with the way a maf works and this fault

but think I understand about the maf, due to it not getting the correct designed amount of air the maf goes into a default setting that is governed by the ecu as a way of a fail safe

so if the large turbo hose at the front was off it was getting far more air than it should do

hope that may make some sort of sense or am I barking up the wrong tree and miles off track

sorry being a bit dense , lol
Click to expand...
Hi Gary, ok, look at it this way, the MAF - a MASS AIRFLOW SENSOR is just what it says. I basically consists of a heated element and intake air temp sensor. In a normal working environment, ALL air entering the engine comes through the MAF... as air enters, the heated sensor decreases in temperature depending on the airflow past the heated sensor... this enables a measurement of the MASS of air... the MASS of air is related to the air temperature (Boyle's law) - so given both mass and temp the actual mass of air entering can be measured - consider it the 'amount' if you will but corrected for temperature -. The partial pressure of the O2 will be in direct proportion to the overall pressure (Mass) (See Dalton's Law.)
As 'air' contain around 20% oxygen we can calculate the amount of O2 in the incoming air in direct relationship to the weight (mass) of air... the O2 percentage remains constant IF you allow for the changing temperature or the mass of incoming air (MASS - weight in effect here)
So, we now know the Oxygen content consumed - or /inhaled/ by the engine. We know the best ratio of mass of air to mass of fuel (Stoichiemetry) (google lol)
SO, the ECU can apply a maximum fuelling value based on the MAF )(MASS) sensor reading.
Ok, so now put a split or a leak in the system from the MAF TO the turbo inlet.... this means 'air' -of unknown mass) is entering the system as well as the air from the MAF - the MAF sees a LOWER MASS of air - hence lower O2 - hence signals the ECU to reduce fuelling !! !(BIG PROBLEM!) ... the issue is the leak in the air intake that is effectively allowing intake air to bypass the maf... the maf thinks the air intake *weight* or 'partial pressure' content (O2) is less, the ecu signals less fuel - hence - in Occams Razor terms (more or less :) - ) then engine cannot perform - cannot achieve power correctly and runs like Sh!t......

So, to sum up,, if you get an air intake leak /tween maf and intake manifold it is not good and runs like bo11ox --- if you disconnect the MAF and it runs ok - *Hence putting the ECU into fail-safe mode and giving it a basic map - then you have proven your hypothesis (to more than 95% certainly)
The failsafe is a simple map in the ecu that allows for a lower temp air intake (hence higher mass) - it can effectively over fuel the engine but this is of little consequence. (apart from MPG or a tad of black smoke)
The failsafe WILL NOT NORMALLY happens with MAF connected ! - this is important .... it needs a MAF disconnect to work, hence the radical difference noted that indicates a major issue in wither the MAF or the intake - here - the OP replaced the MAF so we can effectively rule that out as the cause - leaving only the intake air bypass as a factor reducing the MAF info to the ECU....
:)

Occams Razor again lol... hope that makes sense Gary mate ?
Joe

Joe ;)
 
Last edited:
Joe_H said:
Sorry, I didn't realise English was not your first Language - search - in your native language for Occams Razor.

Basically - it implies that after all diagnosis , the most logical and simplest is the solution on most cases. As in here, the MAF measure the airflow into the engine (The MASS and Temperature- hence knowing the O2 content) .
The MAF is connected between the air intake and the turbo intake and is supposed to measure ALL air intake and adjust fuelling accordingly - WHEN a leak occurs - such as you had (The intake air BYPASSED the maf, then the MAF signals a lower air mass intake (hence O2) to the ECU and the fuelling is limited.
Because you replaced the maf it was logical that that was NOT the issue. Hence the most likely, simple and most logical explanation was an air intake LEAK after the MAF and BEFORE the turbo - as you found..
When you disconnect the MAF you go to a failsafe mapped setting ignoring the MAF - As this worked ok, you can then logically assume that ALL fuelling / pressure etc is absolutely fine and the issue is one of MAF bypass.

"In science, Occam's razor is used as a heuristic technique (discovery tool) to guide scientists in the development of theoretical models, rather than as an arbiter between published models.[1][2] In the scientific method, Occam's razor is not considered an irrefutable principle of logic or a scientific result; the preference for simplicity in the scientific method is based on the falsifiability criterion. For each accepted explanation of a phenomenon, there may be an extremely large, perhaps even incomprehensible, number of possible and more complex alternatives, because one can always burden failing explanations withad hoc hypotheses to prevent them from being falsified; therefore, simpler theories are preferable to more complex ones because they are moretestable.[3][4][5]"

Joe. and glad all sorted, our repair rates are free lol...
Click to expand...

got it got it hehehe - Occam's razor - getting wiser with each post on this forum :D

what happened is that when I was replacing the maf, I dislodged the pipe myself, since the bloody thing doesn't even have a jubilee clip or something - mehhh
 
Joe_H said:
Hi Gary, ok, look at it this way, the MAF - a MASS AIRFLOW SENSOR is just what it says. I basically consists of a heated element and intake air temp sensor. In a normal working environment, ALL air entering the engine comes through the MAF... as air enters, the heated sensor decreases in temperature depending on the airflow past the heated sensor... this enables a measurement of the MASS of air... the MASS of air is related tot he air temperature (Boyles law) - so given both mass and temp the actual mass of air entering can be measured - consider it the 'amount' if you will but corrected for temperature -
As 'air' contain around 20% oxygen we can calculate the amount of O2 in the incoming air in direct relationship to the weight (mass) of air... the O2 percentage remians constant IF you allow for the changing temperature of the mass of incoming air (MASS - weight in effect here)
So, we now know the Oxygen content consumed - or /inhaled/ by the engine. We know the best ration of mass of air to mass of fuel (Stoichiemetry) (google lol)
SO, the ECU can apply a maximum fuelling value based on the MAF )(MASS) sensor reading.
Oj, so not put a split or a leak in the system from the MAF TO the turbo inlet.... this means 'air' unknown mass) is entering the system as well as the air from the MAF - the MAF sees a lower MASS of air - hence lower O2 - hence the ECU reduces fuelling ... the issue is the leak in the air intake that is effectively allowing intake air to bypass the maf... the maf thinks the air intake *weight' of partial content (O2) is less, the ecu signals less fuel - hence - in Ocaams Razor terms (not really but) - then engine cannot perform - cannot achieve power correctly and runs like Sh!t......

Joe ;)
Click to expand...

thanks joe , most appreciated and believe it or not do now understand the principle

compared it to how a boiler works ,as I find that easy with the complicated sensors etc and how the adjustments are made and controlled through sensors

bless u for taking the time , always had the view in having to understand in how something works before u can ever know the fault or repairing it

am getting there slowly but surely in how engines work , lol
 
gstuart said:
thanks joe , most appreciated and believe it or not do now understand the principle

compared it to how a boiler works ,as I find that easy with the complicated sensors etc and how the adjustments are made and controlled through sensors

bless u for taking the time , always had the view in having to understand in how something works before u can ever know the fault or repairing it

am getting there slowly but surely in how engines work , lol
Click to expand...
Actually Gary, I tend to think in your sort of terms.. Airflow can be equated to 'liquid' flow - a MAF issue could be related to an intake leak prior to a pressure pump on a water system. The MAF reading could also relate to a pressure reading POST pump... if air is allowed PRE pump then the POST pump reading is lower.
Most airflow situations are totally in proportion to fluid flow dynamics - air is a fluid to all intents.
Just look at it in that way... all the fancy names could be replaced in terms that you know and work with every day....
Joe
 
Joe_H said:
Actually Gary, I tend to think in your sort of terms.. Airflow can be equated to 'liquid' flow - a MAF issue could be related to an intake leak prior to a pressure pump on a water system. The MAF reading could also relate to a pressure reading POST pump... if air is allowed PRE pump then the POST pump reading is lower.
Most airflow situations are totally in proportion to fluid flow dynamics - air is a fluid to all intents.
Just look at it in that way... all the fancy names could be replaced in terms that you know and work with every day....
Joe
Click to expand...

thks joe , does indeed make a lot of sense , have a very good technical knowledge of the heating systems and its controls and making a lot more sense in u putting it in that terminology

was the same when I started to learn wiring up heating controls and boilers, struggle then one day the penny just dropped and came considerably easier

agree also is better to not ever over complicate things but starting with the basics of what the engine needs and what can effect that
 
Joe_H said:
Hi Gary, ok, look at it this way, the MAF - a MASS AIRFLOW SENSOR is just what it says. I basically consists of a heated element and intake air temp sensor. In a normal working environment, ALL air entering the engine comes through the MAF... as air enters, the heated sensor decreases in temperature depending on the airflow past the heated sensor... this enables a measurement of the MASS of air... the MASS of air is related to the air temperature (Boyle's law) - so given both mass and temp the actual mass of air entering can be measured - consider it the 'amount' if you will but corrected for temperature -. The partial pressure of the O2 will be in direct proportion to the overall pressure (Mass) (See Dalton's Law.)
As 'air' contain around 20% oxygen we can calculate the amount of O2 in the incoming air in direct relationship to the weight (mass) of air... the O2 percentage remains constant IF you allow for the changing temperature or the mass of incoming air (MASS - weight in effect here)
So, we now know the Oxygen content consumed - or /inhaled/ by the engine. We know the best ratio of mass of air to mass of fuel (Stoichiemetry) (google lol)
SO, the ECU can apply a maximum fuelling value based on the MAF )(MASS) sensor reading.
Ok, so now put a split or a leak in the system from the MAF TO the turbo inlet.... this means 'air' -of unknown mass) is entering the system as well as the air from the MAF - the MAF sees a LOWER MASS of air - hence lower O2 - hence signals the ECU to reduce fuelling !! !(BIG PROBLEM!) ... the issue is the leak in the air intake that is effectively allowing intake air to bypass the maf... the maf thinks the air intake *weight* or 'partial pressure' content (O2) is less, the ecu signals less fuel - hence - in Occams Razor terms (more or less :) - ) then engine cannot perform - cannot achieve power correctly and runs like Sh!t......

So, to sum up,, if you get an air intake leak /tween maf and intake manifold it is not good and runs like bo11ox --- if you disconnect the MAF and it runs ok - *Hence putting the ECU into fail-safe mode and giving it a basic map - then you have proven your hypothesis (to more than 95% certainly)
The failsafe is a simple map in the ecu that allows for a lower temp air intake (hence higher mass) - it can effectively over fuel the engine but this is of little consequence. (apart from MPG or a tad of black smoke)
The failsafe WILL NOT NORMALLY happens with MAF connected ! - this is important .... it needs a MAF disconnect to work, hence the radical difference noted that indicates a major issue in wither the MAF or the intake - here - the OP replaced the MAF so we can effectively rule that out as the cause - leaving only the intake air bypass as a factor reducing the MAF info to the ECU....
:)

Occams Razor again lol... hope that makes sense Gary mate ?
Joe

Joe ;)
Click to expand...
This.
Unless your name is Wammers, when you'll argue that it's wrong and a diesel just shirts in fuel.
 
Joe_H said:
lol ;) .......... Noooooooooooo.. that is normal, I have been programming for nearly 8 hours solid today - so is quite therapeutic to discuss 'normal' things :D

Or, would you prefer to discuss C programming function call syntax in Arduino ? :(:confused::rolleyes:

:mad:
Click to expand...

hang on while I pick up my exploded brain off the floor , :D:D

I always enjoyed doing fault finding on heating systems and wiring faults within them , sense of satisfaction when others tried and failed to find the fault
 
Joe_H said:
Hi Gary, ok, look at it this way, the MAF - a MASS AIRFLOW SENSOR is just what it says. I basically consists of a heated element and intake air temp sensor. In a normal working environment, ALL air entering the engine comes through the MAF... as air enters, the heated sensor decreases in temperature depending on the airflow past the heated sensor... this enables a measurement of the MASS of air... the MASS of air is related to the air temperature (Boyle's law) - so given both mass and temp the actual mass of air entering can be measured - consider it the 'amount' if you will but corrected for temperature -. The partial pressure of the O2 will be in direct proportion to the overall pressure (Mass) (See Dalton's Law.)
As 'air' contain around 20% oxygen we can calculate the amount of O2 in the incoming air in direct relationship to the weight (mass) of air... the O2 percentage remains constant IF you allow for the changing temperature or the mass of incoming air (MASS - weight in effect here)
So, we now know the Oxygen content consumed - or /inhaled/ by the engine. We know the best ratio of mass of air to mass of fuel (Stoichiemetry) (google lol)
SO, the ECU can apply a maximum fuelling value based on the MAF )(MASS) sensor reading.
Ok, so now put a split or a leak in the system from the MAF TO the turbo inlet.... this means 'air' -of unknown mass) is entering the system as well as the air from the MAF - the MAF sees a LOWER MASS of air - hence lower O2 - hence signals the ECU to reduce fuelling !! !(BIG PROBLEM!) ... the issue is the leak in the air intake that is effectively allowing intake air to bypass the maf... the maf thinks the air intake *weight* or 'partial pressure' content (O2) is less, the ecu signals less fuel - hence - in Occams Razor terms (more or less :) - ) then engine cannot perform - cannot achieve power correctly and runs like Sh!t......

So, to sum up,, if you get an air intake leak /tween maf and intake manifold it is not good and runs like bo11ox --- if you disconnect the MAF and it runs ok - *Hence putting the ECU into fail-safe mode and giving it a basic map - then you have proven your hypothesis (to more than 95% certainly)
The failsafe is a simple map in the ecu that allows for a lower temp air intake (hence higher mass) - it can effectively over fuel the engine but this is of little consequence. (apart from MPG or a tad of black smoke)
The failsafe WILL NOT NORMALLY happens with MAF connected ! - this is important .... it needs a MAF disconnect to work, hence the radical difference noted that indicates a major issue in wither the MAF or the intake - here - the OP replaced the MAF so we can effectively rule that out as the cause - leaving only the intake air bypass as a factor reducing the MAF info to the ECU....
:)

Occams Razor again lol... hope that makes sense Gary mate ?
Joe

Joe ;)
Click to expand...

For diesel engines total rubbish. At any given manifold pressure air is constant and there is always more oxygenated air in the cylinders than the engine needs to burn the fuel. Even with the engine flat out. The mixture ratio at idle will be well over 100 to one. EGR is used to reduce oxygenated air cool the combustion and reduce Nox output. When EGR is in operation the MAF sensor measures the REDUCTION in air flow as exhaust gas is introduced. The ECU then uses this airflow reading to modulate the EGR valve to control the input of exhaust gas to reduce the amount of oxygenated air to that needed to provide good combustion and reduce Nox. The TD4 uses ECD3 as it's emissions standard. Over active EGR can cause soot deposits to form later version Eg ECD4 are even closer controlled and are fitted with particle filters to collect the resulting output of much finer controlled EGR. Diesels are throttled by fuel NOT by air, what part of that do you not understand?
 
Last edited:
Nodge68 said:
This.
Unless your name is Wammers, when you'll argue that it's wrong and a diesel just shirts in fuel.
Click to expand...

It does. Diesels are throttled by fuel NOT bloody air, what part of that do you not understand? Dear me. At idle of 780 RPM with there is 487.75 cc of air in the firing cylinder. The ECU is injecting enough fuel to maintain 780 RPM into that air. The mixture ratio at this time will be well over 100 to 1 how is the airflow through the MAF effecting that. If there was no turbo to consider for easy of explanation, with the engine flat out there would still be 487.75 cc of air in the firing cylinder. The only thing that changes to make the engine rev flat out is the fuel being injected into that air. If there was no EGR on the engine to accommodate ECD 2 and up there would be no need for a MAF sensor.
 
wammers said:
For diesel engines total rubbish. At any given manifold pressure air is constant and there is always more oxygenated air in the cylinders than the engine needs to burn the fuel. Even with the engine flat out. The mixture ratio at idle will be well over 100 to one. EGR is used in to reduce oxygenated air cool the combustion and reduce Nox output. When EGR is in operation the MAF sensor measures the REDUCTION in air flow as exhaust gas is introduced. The ECU then uses this airflow reading to modulate the EGR valve to control the input of exhaust gas to reduce the amount of oxygenated air to that needed to provide good combustion and reduce Nox. The TD4 uses ECD3 as it's emissions standard. Over active EGR can cause soot deposits to form later version Eg ECD4 are even closer controlled and are fitted with particle filters to collect the resulting output of much finer controlled EGR. Diesels are throttled by fuel NOT by air, what part of that do you not understand?
Click to expand...

Errrm, Mr Moron... Nobody here is talking about EGR.. WTF ate you talking about ? - or - do you want to start another 'think before you post'' thread' You have obviously not moved on from tractors of the 1950's to any modern diesel. Diesels are 'controlled' (throttled if you want' by 'air' (loose term for morons like you) in relation to O2 content and a precise fuel mix. You REALLY have not got a clue. I am amazed. You can read fact, or you can believe fiction. You are thee Beatrix Potter of Diesel engine operations. Absolutely unbelievable.
Good to have 'enticed you back' though, the dumb factor from you is a pleasure to behold and written forever on these walls - I will quote every post so you cannot change your tiny mind.

Ok, numbskull -- ;) - WHAT is a MAF sensor on a TD4 ? - what function does it perform oh knowledgeable one. ? - I await your description with lube in hand...

"Wammers, the things you know wouldn't fit on a postage stamp."
 
Last edited:
Sorry Joe. I couldn't resist seeing if that tractor loving dope would show up. It's so funny to taunt someone well and truly stuck in the early days of diesel power.
I'm waiting to read the answer as to what the TD4 MAF is actually for.
:p
 
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