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

I agree with what Pete is saying Tombie, but how does the ECU run perfectly well with the MAF disconnected which no noticeable loss in performance, engine response, or change in EGT, and without even triggering a fault code?

The theory everyone is quoting make sense, but in my own testing disconnecting a perfectly working MAF had no impact on a manual Td5 with the EU3 motor and EGR bypassed. It is as if when the MAF is good it is purely a comparison reading to the calculated mass air flow from the MAP compensated for temp and altitude, but disconnecting it does not use nor need to use this reading.

Having thought about EU3 TD5s, I think that they had to get AF control very accurate to get through EU3 tests. AFAIK it would not meet EU4 and that is why they went to 2.4 PUMA , which then could not meet EU5, and so to 2.2PUMA
I have read an article in LRO by one of the development engineers that the EU3 TD5 was so clean that it didn't really need a Cat But with production tolerances some may be outside EU3 and they couldn't Guarantee compliance without the cat.

Why otherwise would they fit a fuel temperature regulator, air temp sensors, and have a MAF as well?.

When you disable the MAF, I would think the thing is still pretty clean , but maybe not enough to pass EU3, which they have to do at every MOT in UK.

So maybe in the real world it doesn't matter that much, but I still wouldn't replace the MAF signal with an accelerator position signal , as it MUST be dirtier and create conditions that the ECU cannot handle..
Interesting discussion though.
Regards Philip A

Interesting.

With MAF disconnected on a perfectly functioning manual vehicle and using varying degrees of throttle for take off, acceleration etc I managed to get hesitation, jerking, and copious amounts of smoke.

Originally this was found when the dealer at the time failed to reconnect the MAF after a service

I then went on to repeat the tests connected and otherwise, logging the outputs from the MAF on rovacom.

There is a huge difference between throttle position and air flow, something the linear behaviour of the mod above cannot match.

Eg, loaded, low rpm up a hill will have the throttle reading high, whilst the engine is only gulping air for low rpm.

i didnt want to resurect the old debate about what the MAF does or what it generaly means, IMO the only important thing which is to be clarified here is that how the MAF signal involvment was conceived IN THE Td5 MANAGEMENT cos from what i've seen untill now an open circuit would not affect anything and other kind of faults like some short or modified signal due to some inmternal electric cfailure of the MAF's electronic board might have a bad effect to the engine's running cos the MAF is on the same circuit with the wastegate modulator and a drain below F2's power(as to not blow it) could induce a voltage drop and affect it's behaviour.... i have some more electric tests to do on this but i'll check well this theory too

i'll make a complete log with different tests along a long term observation with the EGT readings cos at the first sight there's no problem there

what is really interesting and i hope i or we'll find out together is that IF the Td5 management isn't eventually based on the speed-density method, a friend of mine who works in ECU tuning business claims that the Td5 ECU is a transfrormed older generation petrol ECU so it might not be impossible ... and then even RAVE was not to be blamed as inaccurrate

what's REALLY strange is that it's different from one car(Td5) to another ???

Waste gate modulator doesn't even enter into the equation when it's a defender either...

The Lucas TD5 ECU was built from the ground up and has many features never implemented into vehicles.

At the end of the day, looking at it logically - you are providing a linear signal to a variable input.
As seen, the results are increased fueling outside normal behaviors which in un chipped vehicles gives a slight increase.

However, your insistence that the MAF is only used for EGR control is debunked by all results, and the associated tables within the ECU which take a feed from said component.

Yet, you continue to push your point as correct. As per several posts I have seen where you provide "text book" or anecdotal evidence (battery thread springs to mind) your mind set is not based on real world experience.

We have a lot of those people at work - recent Degree holders - we call them Graduates. And the truly successful ones adjust their thinking when out in the real world.

i'm just searching for a CLEAR answer here in a completely unclear situation... if the fact that i'm not from down under means i'm not from the real world it's a shame what can i say... i'm not gonna repeat all i've said but please dont expect me to just forget all i've seen with my own eyes and tested from pure electronic point of view with the oscilloscope just cos it doesnt look good for others and snub me all the time instead of giving clear counterarguments others than i'm just stupid or my studies are not as good as other's

i'm trying to find out why it's not the same for all and for some it really behaves like the MAF was mainly for EGR and for others not, that's all

so IMO and by other low class Graduates like me, based on a unreal world experience some facts:

1. If with unplugged MAF the Td5 doesnt behave normally(i dont say perfect) then something else is wrong too and must be investigated.
2. Td5 engine when it was first used it was conceived with EGR so with MAF too and if later on some markets they've got rid only of EGR but kept the same ECU which expects MAF inputs it seems normal to me that they didnt get rid of the MAF too
3. using a linear input instead of a logaritmic one in an application where only a short circuit or a signal out of a range can hurt is not a crime ... why dont you blame the so named "boost boxes" which are simple voltage limiters used on the MAP signal and could hurt much more the engine

i tried to use as much as possible the IMO prefix especially to highlight that it's MY opinion and i didnt expect that in "anno domini" 2014 to be humiliated for that by somebody from a civilised world(or real world?) just cos my opinion differs by other's ...also i dunno what anecdotal evidence did you find in a battery thread but maybe even Kirchhoff's law might seem anecdotal to you

if i became annoying with my research and opinios i hope that a moderator or administrator will notify me on that and i'll shut up for ever



My best regards Fery

Firstly let me offer you an apology for my blunt post; subtly discussion isn't my primary skill set.

Your location had no bearing on my statement...

Real world means "got out there and experienced" not "sat at a test bench probing ports" - not your geographic position on this globe.

Now back to the engine:

The South African market never had EGR, so was designed that way from the get go - the files used there suit their region and vehicle.

The vehicle will baulk with the MAF disconnected even if all the remaining components of the engine are in spec - it depends on how you load it up.

ECU safety cuts are a combination of MAF, IAP and RPM so a boost box will only impede one, not all safety parameters and the better units have a threshold that triggers if exceeded on input to prevent getting to over zealous.

I am not annoyed by your enthusiasm, not your attempts to decipher the workings of the TD5 engine management.

I am however cautious of persons who waltz into a forum, post unproven "fixes" and proceed to vehemently argue that they are right against all other information to the contrary.

The worlds best tuners do not disable the MAF function even though all recommend the removal of EGR on tuned (& stock) TD5s.

***I also at no stage called you a low glass graduate, rather I hinted at lacking real "in the field" experience with this engine. Very different, and something all learned people need to hone their skill set.

As for background, I did electronic warfare systems for a living on military aircraft. I have the raw code from these ECUs and like another, now less active member of this board have a pretty darn good understanding of the Lucas ECU.

I look forward to your continued participation in this forum; you bring a passion for knowledge that can only drive better outcomes for you and the broader community.

Thank you, i accept that...so to start with a "clean page", what's the explanation of the fact that for some of them disconnecting the MAF would mix up the behaviour and others dont even notice it ?