jamesmartin · Jul 30, 2019

Bobdog said:
Ahh... so in a non-turbo diesel, the air is constant, so fuelling is decided by the 'right foot'. However in a turbo diesel, the air flow is variable so there needs to be a way to measure it to adjust fuelling accordingly - i.e. a MAF sensor?....

not exactly on a turbo with a mechanical fuel pump, turbo has a pipe to the injection pump boost valve so as boost increases the amount of fuel is increased which is why boost pins and adjustment are used to increase that further so more power,air to fuel ratio isnt really the issue unless theres not enough air to get full power,but that creates nox , with the need to control emissions high injection pressures ,egrs and sensors fine tune the air to fuel ratio to reduce emissions, whereas a petrol engine allways used a butterfly to control the air entering the cylinder and so the amount of fuel with carbs as it was air that took the fuel, when they became injected you still had a butterfly altering the air but that had to be measured so the injectors could be told what amount to inject , so with a petrol it was the amount of air you let in that governed the engine speed where with a diesel primarily its the amount of fuel

jamesmartin · Jul 30, 2019

Bobdog said:
Oh I've read it....
I can see both sides of the argument but I haven't seen conclusive evidence either way, as to whether you need a MAF if you have deleted the EGR, or not...

in theory you dont and didnt,if you think of a egr 300tdi it has and maf sensor and a temp sensor separate to the dash gauge sensor,but a td5 messures air pressure ,flow and temp as well as engine temp , all modern engines will use every sensor to fine tune fueling for emissions,even to the point knock sensors are used to fine tune ignition timing

Bobdog · Jul 30, 2019

jamesmartin said:
in theory you dont and didnt,if you think of a egr 300tdi it has and maf sensor and a temp sensor separate to the dash gauge sensor,but a td5 messures air pressure ,flow and temp as well as engine temp , all modern engines will use every sensor to fine tune fueling for emissions,even to the point knock sensors are used to fine tune ignition timing

So would i be right in saying, that on a de-EGR'd Td5, (due to all the other sensors) whether the MAF is working or not makes little or no difference?

sierrafery · Jul 30, 2019

Bobdog said:
So would i be right in saying, that on a de-EGR'd Td5, (due to all the other sensors) whether the MAF is working or not makes little or no difference?

Sorry Sir. I promissed that i'll not comment on this but you said you read the "debate" i linked ... maybe you didnt pay attention then cos there are clear explanations and evidences.

about the bolded part i'll comment just that it's valid only for Eu2 engines but completely wrong for Eu3 which's fuelling management is based mainly on MAF/rpm algorythm albeit it kicks in for Eu2 too through the EGR management's "back door" as long as the ECU is not remapped as the EGR to be "erased" and the airmass to be neglected completely cos only by removing the EGR valves the ECU's set up remains the same and it will go to default for "EGR valve stuck closed"... and with that i hope i can rest my case for good, i'm sure that this link was already revealed in my endless debates with mr Wammers but if you want evidence and you can understand here's the full explanation http://www.discotd5.com/td5-tuning/airmass ... if what's there is not enough then nothing will be and you can compare the td5 with Rudolph Diesel's first prototype and get rid of the MAF completely.

Bobdog · Jul 30, 2019

sierrafery said:
Sorry Sir. I promissed that i'll not comment on this but you said you read the "debate" i linked ... maybe you didnt pay attention then cos there are clear explanations and evidences.

about the bolded part i'll comment just that it's valid only for Eu2 engines but completely wrong for Eu3 which's fuelling management is based mainly on MAF/rpm algorythm albeit it kicks in for Eu2 too through the EGR management's "back door" as long as the ECU is not remapped as the EGR to be "erased" and the airmass to be neglected completely cos only by removing the EGR valves the ECU's set up remains the same and it will go to default for "EGR valve stuck closed"... and with that i hope i can rest my case for good, i'm sure that this link was already revealed in my endless debates with mr Wammers but if you want evidence and you can understand here's the full explanation http://www.discotd5.com/td5-tuning/airmass ... if what's there is not enough then nothing will be and you can compare the td5 with Rudolph Diesel's first prototype and get rid of the MAF completely.

I read the debate, you make some valid points but it appears you didn't convince wammers....

I'm not an electrical engineer so I'm trying to simplify this into layman's terms. Based on your (and Jamesmartin's) explanations and the link you provided,
If I were to refine my earlier statement to- 'on a de-EGR'd EU2 Td5, whether the MAF is working or not makes little or no difference'
Would that be correct?
The link even says that on an EU3 engine, if the MAF is faulty, the ECU reverts to using the MAP and the IAT to measure airflow- as in the EU2 engine.

sierrafery · Jul 30, 2019

Bobdog said:
If I were to refine my earlier statement to- 'on a de-EGR'd EU2 Td5, whether the MAF is working or not makes little or no difference'
Would that be correct?
The link even says that on an EU3 engine, if the MAF is faulty, the ECU reverts to using the MAP and the IAT to measure airflow- as in the EU2 engine.

Now it's correct... albeit i'd remove the red bolded part cos what ever it does there is a slight difference as long as it's not remapped as i explained above

it's well known that the Eu3s are running sweeter and with a bit more power than the Eu2s(provided they are 100% OK) so it would be a shame to degrade an Eu3 engine to work like a Eu2 one just to get rid of the MAF IMO

as about convincing someone who's convinced already about the opposite is like trying to convince a surgeon that a tumour can be cured with herbal tea and no need for surgery

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