Disco 2 EGR removal improvements

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sierrafery said:
You know your stuff about how the engine works i have no doubt about that off course i know that the suction through MAF will be throttle dependent but it seems you refuse to aknowledge what i'm trying to demonstrate: vehicle stationary, no load change on the engine, i fixed the throttle with a piece of wood to keep constant 2500 rpm , ECT and FT were constant as well then i played with the MAF input between 1.5 and 4.5V and the signal from ECU to injectors reacted to the MAF voltage changes so did the rpm(+/- 50)....period, even a small puff of black smoke was visible on low MAF input... I've seen this with my own eyes but next time i'll record it on video if you dont believe me
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You believe whatever you want to believe but i can assure you the airflow through the MAF sensor does NOT control fuelling. Providing the EGR system is working properly the only benefit of disabling it is that you don't have to clean the crap out of the EGR valve on a regular basis. You say yours is disabled was it EGR 1 or EGR 2?
 
Mine was EGR1(provided you mean the one valve version with that), just to clarify, i'm not saying that the air flow through MAF CONTROLS fuelling, just that the MAF's input is part of the ECU's addaptive strategy for fuelling and has a certain effect on it so the MAF is not there ONLY for EGR controll as long as the electronic unit injectors management is affected by it's inputs, cos that was how thois whole discussion started...also it's a fact that in the Td5 ECU's fuel map there's a fuel-air calibration table stored part of the addaptive strategy and the EGR management is not part of this particular ''file''. If the MAF was there only for EGR then with an unplugged modulator and "EGR stuck closed"(or any other EGR related) fault code logged the ECU would have switched to a default where the MAF signal to be completely neglected cos that's how electronic management are working.

to cut a long story short, you need a well working MAF sensor for a well running Td5 engine with a decent consumption even without EGR so everybody can throw his own conclusion if the MAF is partially involved in fuelling or not.
 
sierrafery said:
Mine was EGR1(provided you mean the one valve version with that), just to clarify, i'm not saying that the air flow through MAF CONTROLS fuelling, just that the MAF's input is part of the ECU's addaptive strategy for fuelling and has a certain effect on it so the MAF is not there ONLY for EGR controll as long as the electronic unit injectors management is affected by it's inputs, cos that was how thois whole discussion started...also it's a fact that in the Td5 ECU's fuel map there's a fuel-air calibration table stored part of the addaptive strategy and the EGR management is not part of this particular ''file''. If the MAF was there only for EGR then with an unplugged modulator and "EGR stuck closed"(or any other EGR related) fault code logged the ECU would have switched to a default where the MAF signal to be completely neglected cos that's how electronic management are working.

to cut a long story short, you need a well working MAF sensor for a well running Td5 engine with a decent consumption even without EGR so everybody can throw his own conclusion if the MAF is partially involved in fuelling or not.
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Fuelling is not adjusted subject to airflow. I will say again for any given RPM, power demand, manifold pressure, air is constant. The ONLY thing that determines fuelling is the RPM required. More fuel higher RPM less fuel lower RPM. I have seen it mentioned on here to remove the electrical plugs from the vacuum valves when disabling EGR. This is a mistake they should be left connected, just the vac pipes removed and blanked off. Any circuit left disconnected will confuse the ECU.
 
I'm convinced now that even if you are expert in how the combustion process is achieved within the engine you don't know much about how the Td5 electronic management works.... the ECU is never "confused", it's prepared for any open circuit with various default modes addapted for each situation, by removing the vacuum from the valve(s) the ECU will recognise that exactly based on MAF and IAT inputs so it will be on "EGR stuck closed" default anyway but will "insist" through the soilenoid to get it opened so the unnecesary load on the MAF's and wastegate modulator circuit(as they're on the same fuse) is completely futile especially that the solenoids will get hot and draw more by working in vain.

as about that statement: "for any given RPM, power demand, manifold pressure, air is constant" IMO the rpm and manifold pressure will depend on how the management adjusts fuelling based on ALL sensor inputs not just on TPS and the fuelling is determined by the ECU niot by the engine

what do you mean by "air is constant" though cos i presume you mean only volume while it's much more involved when we speak about air mass, and for the management the mass is important
 
sierrafery said:
I'm convinced now that even if you are expert in how the combustion process is achieved within the engine you don't know much about how the Td5 electronic management works.... the ECU is never "confused", it's prepared for any open circuit with various default modes addapted for each situation, by removing the vacuum from the valve(s) the ECU will recognise that exactly based on MAF and IAT inputs so it will be on "EGR stuck closed" default anyway but will "insist" through the soilenoid to get it opened so the unnecesary load on the MAF's and wastegate modulator circuit(as they're on the same fuse) is completely futile especially that the solenoids will get hot and draw more by working in vain.

as about that statement: "for any given RPM, power demand, manifold pressure, air is constant" IMO the rpm and manifold pressure will depend on how the management adjusts fuelling based on ALL sensor inputs not just on TPS and the fuelling is determined by the ECU niot by the engine

what do you mean by "air is constant" though cos i presume you mean only volume while it's much more involved when we speak about air mass, and for the management the mass is important
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If you want to keep talking nonsense then that is up to you. Fuel amount injected is a result of RPM and power required, more fuel more RPM, less fuel less RPM. Simple as that. The fuel quantity needing to be injected to achieve any particular engine speed is subject to fuel temperature. Less cold dense fuel or slightly more warm fuel will be injected. How much air goes in through the MAF has nothing to do with it. I will say again. For any given throttle request, manifold pressure, engine speed, air is CONSTANT. That is how a diesel engine works. "Air is constant" is very easy to understand. Take a none turbo diesel engine with cylinders of 500 cc each, there can never be more or less than 500 cc of air in the cylinders. Therefore air is constant. Fuel is injected to give idle speed, where the air to fuel mixture ratio maybe well in excess of 100 to 1, if an higher speed is needed, more fuel is injected to give that speed and so on an so forth up to the maximum governed speed. The air remains constant. On a turbo engine the MAP sensor signals the ECU to increase fuel to maintain any particular power request subject to manifold pressure and fuel map constraints. For any given manifold pressure air in the cylinders is constant. Fuelling is NOT controlled by air flow through the MAF sensor. Simple as that. Fuelling is determined by the speed the engine is requested to run at, and the load the engine needs to overcome to maintain that requested speed and power, within the fuel MAP constraints. On EGR engine with the EGR in operation, exhaust gas is ingested to reduce the amount of combustible oxygenated air to reduce combustion temperatures and reduce Nox production. The MAF sensor is used to measure this exhaust gas ingestion and inform the ECU by signaling reduced air flow. The ECU then modulates the vacuum valves to control this ingestion. This was explained earlier.
 
wammers said:
Each to their own. Carry on. Some day the light will shine.
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Maybe, the question is for whom?, for me and those ho wrote the quoted parts already shown here https://www.landyzone.co.uk/land-rover/egr-removal-improvements.289849/page-2#post-3597703 , or for you when it'll become clear that IF and electronic unit was built as to work with the MAF signal too for injector management that's what it will do, not become confused or do what the engine wants

another flavour of some guys who are speaking nonsense in official documents:
Td6 MAF.jpg
 
Someone might have hooked it up to the EGR, and we would all be speaking German now.
Least we would have a football team to cheer for.
 
Pity they didn't have a TD5 ECM at Bletchley Park in 1941 the war would have been over by 1943.
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I think that's why it's so hard for you to accept how the MAF can be involved in injector management cos you compare a new generation 100% electronic ECU + EEPROM with an ancient electro-mechanical cipher machine:cool:
 
sierrafery said:
I think that's why it's so hard for you to accept how the MAF can be involved in injector management cos you compare a new generation 100% electronic ECU + EEPROM with an ancient electro-mechanical cipher machine:cool:
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There is ALWAYS more air than needed for combustion in a diesel cylinder. What makes the engine go bang to give any particular requested RPM or power demand is the amount of fuel injected into that air. Diesels are not throttled by air but by fuel. That is something you seem not to be able to grasp.
 
I'm n ot speaking about diesel engine that's the problem of out debate, i'm speaking about the electronic control unit connected to the injectors which reacts to MAF voltage signals on the output to injectors, not about combustion, air, throttle, RPM, etc. ... and according to my own measurements and tests made with reliable tools that's what happens so i'm not gonna think i've had some optical illusions only based on the theory how a diesel engine works from mechanical point of view... blame those who built the Td5 ECU to do that not me cos i'm just observing things ... also those ho wrote the workshop manuals for L322, Td4, Td6 were all stupid? , at post 25 you mentioned BMW...it seems that there are guys who are speaking nonsense about that too: http://bmwgt1.com/bmw-maf-mass-air-flow-sensor/

IT'S ABOUT THE MAF SENSOR AND WHAT THE ECU DOES WITH IT'S SIGNAL FROM ELECTRONIC POINT OF VIEW HERE NOT ABOUT HOW MUCH AIR OR FUEL IS NEEDED FOR COMBUSTION
 
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I'm not too sure what all the squabbling is about?

1 - @wammers is correct The % throttle controls the fuel not the MAF.
2 - @sierrafery is partly correct. The ECU detects when the MAF falls below a certain value and retards the fuelling to compensate (e.g in alpine conditions). This is done in its "Hunt" for optimum value. If The MAF input voltage increases above the set point (assuming standard not remapped ecu) the fuelling is not altered (i.e this only happenen if the MAF reduces, due to thinner air or a larger quantity of EGR). This is why you see the effect when you change he input voltage. This is what Wammers means by "Confused" when you remove the MAF, and why it was also fitted on the early African models without EGR as the basic principle is the same.

The point that is being missed here is that the MAF does not control anything, its used as more of an alarm for the EMS so you don't start belching out diesel.
 
Retrospaceman said:
The point that is being missed here is that the MAF does not control anything, its used as more of an alarm for the EMS so you don't start belching out diesel.
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it wasnt missed by me, see post #62 : "i'm not saying that the air flow through MAF CONTROLS fuelling, just that the MAF's input is part of the ECU's addaptive strategy for fuelling and has a certain effect on it so the MAF is not there ONLY for EGR controll as long as the electronic unit injectors management is affected by it's inputs, cos that was how this whole discussion started"
 
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its very clear in post 72 what the people who designed the system think the MAF does, as i said there is a clue in the name.
 
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