Thread: How to completely get rid of MAF on de-EGR'd TD5

on a second thought, the fact that for Td4 and V8(or others) the MAF is more important is that it's mounted closer to the inlet manifold and it measures the IAT too which is again important...so the fueling calculations are made on the same air for mass and temperature cos that's the air which goes directly into cylinders...i tend to think that this Td5 kind of thing is more accurate as it's based on universal thermodynamics law PV/T = constant, and it's a more stabile environment in the inlet manifold than near the airbox where the MAF is on a Td5. Also for the way it works based on hot filament cooling principle the Td5's MAF will send different readings for the same air mass according to the air's temperature e'g at -5 degrees the element will be cooled by a smaller amount of air like at +30 and the voltage output will be different...while in the inlet manifold once the engine is up to running temperature the outside temperature is not so important ... think about that too before you "sanctify" the Td5's MAF which is near the air intake(measuring the intake air flow) not near(or in) the inlet manifold together with the IAT like on other cars ... i hope we all agree that for good management the calculations have to be made on the inlet air not on the intake air...off course i'm not saying that tey're not interdependent

and please dont forget that my title was How to completely get rid of MAF on de-EGR'd TD5...not any other engine... now i think i should have said manual? maybe?

anybody can point me to a suitable EGT gauge which i can find in Europe?...they are not very popular around here and i have no experience with one.

Hey sierrafery looks like you haven't slept for the last 30 hours going by your post times. Have a break from the keyboard we'll still be here when you get back.

You should be proud of your English. And your manner in engaging in this thread.

thanks...no probs i've been working in shifts as an air traffic controller for 25 years now so dont underestimate my insomnia i've been engineer only for 3 years maybe that's why the other engineers dont understand me

I agree with pibby and rangieman, thanks for your contribution sierrafery and the way you have presented your own personal experience. Have seen your posts on other forums and you are certainly a respected contributor and will be a valued member here.

The debate on what the MAF does is one which has happened on many forums around all 4 corners of the world. RAVE seems to be the source of this confusion based on what it does not say about the MAF. Based on RAVE, the MAF should have no impact once the EGR is removed and yet if faulty it does have an impact. The MAF must have a function beyond just controlling the EGR else it should have no impact when faulty. And for countries which sold the Td5 with the EGR removed then LR engineers being penny pinchers would have removed the MAF as well. These are the same people who removed the CDL internals on the transfer box to save a few dollars.

The best insight into the link between the MAF and impact on fuelling rates can be found in the experience of this post in a South African forum. The post summarised the findings and links to more detail.

http://www.4x4community.co.za/forum/...hp't=52601

With the MAF removed it was found that with the ECU using the default value, it would over fuel at low revs (explaining why it would feel better) but then under fuel at high revs. The MAF was impacting on fuelling rates. RAVE would suggest this should not be the case, but this is what this person found through testing following a remap.

My guess is your mod sierrafery is a more accurate approximation of an over ridden MAF value and could give a crude method of over fuelling over the full rev range which in many circumstances gives better performance. Much like the boxes which intercept the injector harness signal and extend the injection time. The best way to add more fuel and get perfect would still be a remap.

So my view would be if you have a faulty MAF then sierrafery's mod may give a better approximation of the correct MAF reading than the ECU's default values and hence give better performance over the full rev range. And you have to admit that if the mod improved performance by approximating the air flow over the full rev range, then it must be doing something. Otherwise the solution would be to just disconnect and run with the default value.

So I give this a big thumbs up for being a great mod for a faulty MAF, but watching the EGT must be a critical part of this mod to protect the Engine. I would still want to have a proper working MAF connected so I could see what is happening and to allow the ECU to use all the info available to it.

This has been a great and informative topic.

that's what i name friendly polemic , i went through the posts in the link and the link in the link in your post and getting to the same conclusion...that the general approach for that issue is based on the presumption that for the Td5 the MAF is used for fueling calculation contradicting what's in the manual which states that this is based on the MAP/IAT readings... i checked the documentation for what's in my RAVE and i can tell that every engine's management there is different so there isn't a clear pattern to generalise, from what i have, based on what's stated in the book the conclusion is this(to simplify i'll name genericly "engine management" the fueling/timing/injection/turbocharger/mapping/etc calculations and addaptive strategy)

in conjunction with all the other INVOLVED sensors:
1. the MAF/IAT sensor is used MAINLY for engine management on V8 and Td4 engines
2. for Td5 the engine management is MAINLY based on the MAP/IAT input
3. for the 1.8 and KV6 Freelander petrol engines(MEMS and Siemens management) the engine management is based on the MAP/IAT sensor as well and these dont even have a MAF

i'll fit an EGT gauge on mine soon especially to get to the end of this debate and if it will show that this mod is dangerous i'll be fair enough to admit that i was wrong... but based on my tests untill now and the fact that i drove 30000km with this mod often towing 1500Kg from time to time at more than 30*C outside temp without any probs i'll stick to my ideea and believe what's in the BOOK that FOR the Td5 the MAF is used MAINLY for EGR controll and it will disturb the management when it's faulty but an emulated signal which is close to the reality will not cause any trouble.

it seems more accurate to me the MAP signal anyway for management cos it comes from a more stabile environment with smaller temperature differencies and measuring the actual air which is used for combustion, as i explained sooner the MAF will have up to 1.5V difference in reading at the same air flow if the temperature difference is 40*C( let's say -5 and +35)which is very common around here cos it works based on the filament'resistance change achieved by cooling...to not say that here the temp in winter goes down to -25 and rises to +40 in the summer so at 65*C diffrence there could be even 2.5V difference in the output AT THE SAME AIR FLOW so for the ECM based on the voltage input there is a different air flow then(even if it's not) cos it corroborates the voltage with the mass of intake air if you see what i mean.

Originally Posted by sierrafery

that's what i name friendly polemic , i went through the posts in the link and the link in the link in your post and getting to the same conclusion...that the general approach for that issue is based on the presumption that for the Td5 the MAF is used for fueling calculation contradicting what's in the manual which states that this is based on the MAP/IAT readings... i checked the documentation for what's in my RAVE and i can tell that every engine's management there is different so there isn't a clear pattern to generalise, from what i have, based on what's stated in the book the conclusion is this(to simplify i'll name genericly "engine management" the fueling/timing/injection/turbocharger/mapping/etc calculations and addaptive strategy)

It appears you are putting 100% faith in a few sentences in the manual not only become completely correct, but being all inclusive and covering all MAF operational functions.

Which is not a move I would take. Especially with all the evidence to the contrary.

Originally Posted by sierrafery

it seems more accurate to me the MAP signal anyway for management cos it comes from a more stabile environment with smaller temperature differencies and measuring the actual air which is used for combustion, as i explained sooner the MAF will have up to 1.5V difference in reading at the same air flow if the temperature difference is 40*C( let's say -5 and +35)which is very common around here cos it works based on the filament'resistance change achieved by cooling...to not say that here the temp in winter goes down to -25 and rises to +40 in the summer so at 65*C diffrence there could be even 2.5V difference in the output AT THE SAME AIR FLOW so for the ECM based on the voltage input there is a different air flow then(even if it's not) cos it corroborates the voltage with the mass of intake air if you see what i mean.

That is how a MAF works. This i why it is called a Mass Airflow Sensor and not a Volume Airflow Sensor.
The same volume flow at cooler temperatures gives higher mass flow and a higher reading on the MAF.

Originally Posted by rangieman

But its still possble and happens with out all the doom and gloom

A petrol with a MAFless tune has the engine management severely compromised. Fuel economy will be complete poo. It is a modification only done when chasing maximum power for a dyno queen.

Originally Posted by clubagreenie

Got a solution for 38L/100 economy when EVERY sensor and ECU have been replaced and the engine overhauled and stripped back down to check cam timing etc?

Get thee a wide-band O2 sensor and gauge. Stick on the end of the exhaust and the results should give you some clues. It was the first vital step in remapping my rover V8.

Originally Posted by Dougal

1.It appears you are putting 100% faith in a few sentences in the manual not only become completely correct, but being all inclusive and covering all MAF operational functions.

2.Which is not a move I would take. Especially with all the evidence to the contrary.



3.That is how a MAF works. This i why it is called a Mass Airflow Sensor and not a Volume Airflow Sensor.
The same volume flow at cooler temperatures gives higher mass flow and a higher reading on the MAF.

1. everything i've learned in my life(and i've learned a lot) it was from books and real life experiences, when i'll realise that i can't rely on these things i'll quit thinking

2. so you name "evidence to the contrary" the fact that i've done 30000km with this mod without any issues and average 9.5% consumption? , for me it's everything but to the contrary... IMO untill now in this thread there were only various OPINIONS from both sides, no EVIDENCE

3. we agree on how MAF works(what's bolded, except the red part)...how is that(maybe my english is not good enough to understand) afaik air mass is about volume and density, not about temperature, that's why on those cars where the MAF is mainly used in engine management it's together with the IAT, as the management to calculate the REAL air mass from the two inputs, again according to the book here's the chart on which the engine management is based(from RAVE)


so for the ECM that's what the MAF reads, e'g for 4V = 400 Kg/hr let's name it "mass" cos in reality it isnt as we agreed that the temperature is important... you are mechanical engineer so i won't enter in sophisticated explanations about how the microprocessor and the EEPROM in the ECM works but if you use just simple logic youl realise that IF this simple ecuation is so important for the Td5's "engine management" then those who are living in areas where there are big temperature differencies between seasons or even day and night(like in the desert) would have serious troubles with the fueling/consumption etc and theyr engine would be in great danger...at least as great as with my mod ... IMO that's why on those cars where the MAF reading is used mainly for engine management it's together with the IAT on the same port and the ECM is specially built/programmed to make calculations based on those two inputs... which the Td5 ECM is not, i've just received the complete database about the ECM (thanks Ian) and i can confirm that ... actually IAT is INLET air temp for some and INTAKE air temp for the others as for the Td5(or other similars) is on the inlet and for V8(and other similars) is on the intake... these things are looking more like an EVIDENCE to me than some simple statements based on a general and pure mechanical/physical view about how a motor works
... but in the end it's also just an opinion...MY opinion ... any other opinion will be gratefully received and respected...at least by ME