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

I intend to reread this thread in detail later on.

But to stir it up a bit more, I thought I would share some details from my own experience with you. When I first started modifying my vehicle I had issues with the engine cutting into limp home mod (significant reduction in power and performance) every time I tried to accelerate hard.
The cause of this was the amount of airflow through the MAF was exceeding its capabilities to read. I tested various other MAFs with no improvement. But if I disconnected the MAF the problem was not there.

The first solution was to fit a modified MAF sensor from Alive Tuning (the old TD5 Alive Alive Tuning ) - the product doesn't exist on their website and they supplied it to me after I had some direct discussion with them, this product resolved my issue, but being a non genuine/OEM MAF it created a new issue of the automatic transmission being a bit rougher in it's operation.
My conclusion therefore - the MAF certainly does effect the automatic transmission, how or why I don't know.

I therefore purchase an IRB Developments Fully Adjustable IRB Anti Limiter Box < IRB Developments > - this is a dual channel product similar to that which Alive Tuning and Bell Auto Services sell - the key difference is that the IRB products effects the signal to the MAF sensor AS WELL!
I therefore removed the Turbo Booster Module < Td5 Turbo Booster Module > and MAF that I had purchased and fitted from Alive Tuning and fitted a brand new OEM MAF and IRB Developments box.
The end result was that it resolved my performance cut out issues and the automatic transmission operates as nice and smooth as a 220,000km unit can be expected to.

I know that there are guys in the UK who have experienced similar issues to me, who run a secondary air intake pipe from the air filter housing into the inlet pipe post-MAF and pre-turbo charger. The purpose is to allow the excess air to not go through (and therefore not be measured by) the MAF sensor.

What you have discussed in this thread offers a possible fourth solution to this issue - i.e. just remove the MAF from functioning.

Your proposal is interesting and I believe certainly has it's merits. I think a large number of people doesn't understand the operation of the MAF on the TD5 vs the functions of the MAP sensor.

Originally Posted by sierrafery

what i can respect is that Mr. Dougal knows lots about diesel engine management

i'm really embarrased that as a newbie here i must contradict you Sir but as Mr. lpower85 , well observed(shame on me i missed that) is that you must speak about some other engine as long as you stated that there's no IAT sensor on a TD5... i quoted only the relevant parts from the workshop manual but all the tests i've made are based on the complete database and electric circuit diagrams too and the results are all relevant

I didn't state there was no IAT. I didn't however know there was one integrated into the MAP sensor. I do now and it doesn't change my concerns at all: Land Rover Workshop Manuals > TD5 Defender > ENGINE MANAGEMENT SYSTEM > SENSOR - MANIFOLD ABSOLUTE PRESSURE (MAP) / INLET AIR TEMPERATURE (IAT)

Please tell us what tests you have actually run and what operating conditions you have simulated!

Originally Posted by sierrafery

the question is what we want from our cars? to run nice and economic or to insist on keeping a (IMO)useless MAF while we've already decided to get rid of the EGR considering it malicious for the engine just cos for the majority of other different diesel engines is important... IMO the description from RAVE is not vague at all when it describes the sensors which are taken into account by the addaptive strategy.... even in a vague description they should have mentioned the MAF if it was so important...but they didnt, in exchange theyn highlighted the CKP, ECT, MAP/IAT, FT and TP sensors... and that's strange isnt it?

What you want from your car and what you consider acceptable may be completely unacceptable or even damage another.
You didn't state if your run an EGT gauge. But I'd expect an engine with your mod (telling the engine it has much higher airflow than it is getting) to run much hotter and even smokier than the factory tune intends.

It would really suck for someone else to melt a piston or two towing after following your advice.

Here is the workshop manual description of the MAF: Land Rover Workshop Manuals > TD5 Defender > ENGINE MANAGEMENT SYSTEM > SENSOR - MASS AIR FLOW (MAF)

It is extremely simplified.

IMO it's a good thread and a nice discussion from which we all can learn something and i hope it will not create animosities... unfortunately i can't vouch 100% that this mod is the best for an auto or not as mine is manual and i know that the autos are more complicated


it's not something vital and can't ruin the engine on a short run anyway(it didnt ruin mine in 30K km, so those who are suspicious about it can try the mod for a short time cos it's very easy to do and completely reversible... then we'll all know if it's good or not regardless of the different theories... as long as we vitiate the system with boost boxes, modified wastegates, bypassed EGR's, voltage clamps, etc it doesnt seem to me that such mod would be bad near the others... cos the fact is that it's tested live and works ... imo it's not "worst" than the voltage limiter on the MAP input ... formally named "Boost box"

Originally Posted by Dougal

I didn't state there was no IAT. I didn't however know there was one integrated into the MAP sensor. I do now and it doesn't change my concerns at all: Land Rover Workshop Manuals > TD5 Defender > ENGINE MANAGEMENT SYSTEM > SENSOR - MANIFOLD ABSOLUTE PRESSURE (MAP) / INLET AIR TEMPERATURE (IAT)

Please tell us what tests you have actually run and what operating conditions you have simulated!



What you want from your car and what you consider acceptable may be completely unacceptable or even damage another.
You didn't state if your run an EGT gauge. But I'd expect an engine with your mod (telling the engine it has much higher airflow than it is getting) to run much hotter and even smokier than the factory tune intends.

It would really suck for someone else to melt a piston or two towing after following your advice.

Here is the workshop manual description of the MAF: Land Rover Workshop Manuals > TD5 Defender > ENGINE MANAGEMENT SYSTEM > SENSOR - MASS AIR FLOW (MAF)

It is extremely simplified.

i know the Discovery 2 workshop manual by heart believe me so there's no reason for those links about Td5 Defender which is a bit different anyway as one of the major differencies is that it doesnt have a wastegate modulator...so we better not compare them


i made too much tests to reveal them here but i can explain one at least even though it's quite hard for me to do that in english

so using a multiple port signal generator and the D2 harnesses, based on the circuit diagrams and description from RAVE i gave all the necessary inputs to the ECM to simulate a running engine at normal operating temperature, which means 3.8V from ECT, 3V from FT, 6.5V from CKT and the dual signal from TP track 1 and 2( neglected 3) + MAF variable ..then i measured the outputs for the EGR modulator, wastegate modulator and for the injectors with oscilloscope and what i found is that even if i imposed a delay or a slight difference on the MAF input as long as it was between 1 and 5 V regardless of throttle position input the only noticeable difference was on the EGR modulator outputs, a max 1% difference on the wastegate modulator downwards(compared to the live measurements on the running car) and no difference on the injector pulsatory outputs...so based on these and on the descriptions i did the mod on my car to realise that it works

imo our "dispute" mr Dougal starts from the fact that you consider that the MAF reading can affect the real air flow or the combustion which is there due to the suction anyway so the engine get it's air to create the combustion without caring of the MAF input cos the fueling/turbocharger is managed based on the MAP/IAT, AAP, TP, ECT and FT inputs... that's also tested cos when i modified the MAP or IAT inputs the signal to the injectors changed accordingly

it's a too long story anyway, especially if you stick to your own theory as i do


aaaa i forgot to mention i have a Hawkeye and a nanocom too and i keep the nanocom permanently on instrument mode first page concentrating on the coolant temp cos i had many problems in the past due to the old pipes which failed one by one and realised only when it went to overheat protection due to lack of coolant once and failed viscous fan other time...but since i've fitted a new genuine viscous unit and a complete silicone hose kit( for coolant system, friggin nexpensive) the coolant temp stays there between 80 and 90 all the time

Originally Posted by sierrafery

imo our "dispute" mr Dougal starts from the fact that you consider that the MAF reading can affect the real air flow or the combustion which is there due to the suction anyway so the engine get it's air to create the combustion without caring of the MAF input cos the fueling/turbocharger is managed based on the MAP/IAT, AAP, TP, ECT and FT inputs... that's also tested cos when i modified the MAP or IAT inputs the signal to the injectors changed accordingly

The MAF doesn't affect the air. The air is determined mainly by rpm and boost. The MAF simply reports the current mass airflow reading to the ECU.

Your modification will always report a higher airflow at full throttle regardless of rpm and boost.
This will cause the ECU to think more air is present and inject more fuel. This is not a good thing.

Originally Posted by sierrafery

there's no reason for those links about Td5 Defender which is a bit different anyway as one of the major differencies is that it doesnt have a wastegate modulator...so we better not compare them

What effect does the wastegate modulator have on this?

D2 owners who have installed the VGT/VNT type turbochargers have removed/disconnect/bypassed their electronic modulator unit.

Hello,
I have been reading this thread with great interest, having no EGR and and Auto I will try this mod...... and see how it goes. Like you say cannot be more harmful than a boost box. The shifting might be a problem.......but my MAF is not in the best condition. Hopefully get onto it today as baby sitting my grandchildren right now. Will keep you posted.
Ian

This is going down very dangerous road of loss of functionality and major misinformation based on a little bit of information is a dangerous thing.

Firstly with all due respect to the original poster, You have no idea of how a MAF work is you only think it does what that excerpt from RAVE describes. You need to understand the RAVE breaks information down into its individual sections and if its talking about MAF control of EGR it's because that information is relevant to the topic it's in relation to.

A MAF sensor measures MASS AIR FLOW. Period. Other systems will use this information in conjunction with other to perform various functions. Example; the auto shifting uses some 30 inputs to calculate when to change gears. MAF is just one, as such EGR control is a function of many inputs not just a voltage signal based on air mass.

Loss of the MAF signal may or may not throw a code and this in conjunction with what may otherwise be a non event fault can combine to create a major fault. For instance, in a V8 model, an intermittent fault with the MAF will interact with O2 sensor signal and cause fueling to go massively awry and from that throw auto codes as the auto cannot deal with the engine load signals combined with the road speed fluctuations, actual TPS signal (which doesn't match air mass flow (intermittently) and send it into limp mode at best (at least it's running) at worst it'll just act up at a certain set of inputs and when plugged in to asses faults, Test Book, Nanocom, Hawkeye and any other OBD2 tester will show an auto fault. A mechanic driving it will also say theres an auto issue as for all intensive purposes it drives like a clutch fault. Rebuild the auto and it will do exactly the same thing. Replace a $2000 MAF sensor and the issue goes away.

MAP sensor detect MANIFOLD ABSOLUTE PRESSURE, may have an inbuilt temp sensor and the signal output is compensated for with temp and ambient atmospheric pressure. They work better for boosted systems as there doesn't need to be an ECU map compensating for air mass and boost pressure. It calculates mass based on pressure (absolute) and avoid having to route inlet tract lines from turbo to intercooler, shove a MAF sensor in there somewhere and then to the plenum.

MAP sensors are used with boosted systems and as asked earlier about why boost boxes use map sensors. One, they are quite small and fit into an aftermarket unit, surface mounted quite easily. It's easier to run a line into the cabin and sense MAP pressure in an aftermarket box than fit a MAF and ru a wiring harness or piggyback onto the OEM MAF signal from somewhere in the wiring.

I would apply this mod with the same caution applied to hi-clones, speaking of which. If I remove the MAF where will my hi-clone fit?