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

Originally Posted by twr7cx

Can you confirm what it is exactly that you mean by this number? You keep writing 30.000km 30.000 is the same number as 30 and 30km is not very much testing - I drive at least that to and from work every day.

Do you mean 30000 or 30,000km perhaps?

i mean 30000 km then, 30.000 means 30 thousands around here exactly like one million is 1.000.000 in all the documents here not 1,000,000

Originally Posted by sierrafery

according to my tests the ECU doesnt "react" on the injector side of outputs no matter how the MAF input is altered as long as it's within limits and the difference from the referrence value are not exagerated... as about RAVE, the description of MAF is in the "Engine management - Description" section where all the other sensors are described and even if i'll admit that it's description has lacks it's not even mentioned in the "operation" chapter where the addaptive strategy is explained.

The MAF input sets those limits. Via the fuel/air calibration tables (aka smoke map).

Originally Posted by sierrafery

starting from the presumption that RAVE is wrong when it describes the MAF's purpose it means that the whole engine mamagement description and operation chapter is wrong which seems quite unbeliavable for me, and it seems exagerated to me to compare the MAF's involvment in the Td5's management with other different engines especially with petrol ones.

Rave isn't wrong. It's just highly simplified in descriptions.

All modern engine controls are speed-density systems which base engine control off torque requests. Just like your TD5.
You keep thinking it's a special case, but it isn't. The biggest difference between petrol and diesel control now is the tightly controlled AF ratios for petrol vs the wider range for diesel.

Originally Posted by sierrafery

if all those apocalyptic theories with how dangerous is that mod and how bad it can affect the engine were real i should have noticed it in the close to 30.000km i've done with it...but no black smoke, no consumption or running issues, nothing... what's the explanation of that if the MAF is involved so hard in fueling?? ...for me it's simple cos i believe what RAVE sais, what my tests revealed and what's happening in reality

Do you tow in hot climates?
Do you run an EGT gauge? The TD5 can produce some seriously high EGT without showing smoke.

Just a quick one..

Whilst seat of the pants is ok, have you got EGT readings or A/F data under all loads and conditions?

i dont have EGT gauge, i keep an eye only on the coolant temp constantly with nanocom, i'm towing a loaded shetland 536 boat with 100bhp engine(around 1500kg) all summer and the temperature is quite often 40*C around here... my dillema still remains that even if the descriptions are highly simplified in RAVE why they dont mention the MAF(being so important) at least once when they describe the addaptive strategy...it's mentioned and described being more important in the V8 section or on freelander engines in RAVE's simplified manner though.... and for thpose engines where the MAF is described being more important than for Td5 is always combined with the IAT like the MAP on the Td5 but the functions are reverted... i reiterate e'g for Td5 they say about the MAF that's only for EGR controll and
1. the MAP/IAT is there:
l To calculate the delivered fuel limits.
l To calculate the air mass in the cylinder.
l To calculate the air speed density.
l To calculate air temperature.

2. The ECM uses the signal from the AAP sensor for the following functions:
l To maintain manifold boost pressure.
l To reduce exhaust smoke emissions while driving at high altitude.
l Control of the EGR system.
The sensor also supplies a voltage between 0v and 5v proportional to ambient temperature. The ECM uses this signal
for the following functions:
l Exhaust gas over temperature protection.
l Turbocharger overspeed protection.

for Td4 they say:
1. The MAF sensor output is an analogue voltage proportional to the mass of the incoming air. The ECM
utilises this data, together with information from the other sensors and the fuelling maps, to determine the correct fuel
quantity to be injected into the cylinders. It is also used as a feedback signal for the EGR system.

2. Boost Pressure (BP) Sensor (which is actually the same as the td5's MAP)
The ECM uses
the signal from the BP sensor for the following functions:
l To maintain manifold boost pressure.
l To reduce exhaust smoke emissions while driving at high altitude.
l Control of the EGR system.
l Control of the vacuum control module

so for the Td4 the MAF/IAT is for fueling and injector engine management and the BP(MAP) is for what the AAP is for the Td5, but on the Td5 the MAP is the most important and it's for the engine management

so IMO simplified or not if those informations are NOT WRONG that's one of the proofs how different can be the management on two different engine... so o won't recommend that mod for a Td4 or V8 whatsoever

and there are more such things but you must have the patience to read the whole RAVE page by page more times like i did...took me one year to do that study just out of hobby... and dont forget that at the basics i'm an engineer

Hmmm... I can belt EGT well outside comfortable levels under load and not see more than 2° temp change at the coolant sensor.

Some good debating going on here
With the usual

Engineers designed the Titanic.
And the Mars lander that impacted like a stone!

I'm going to pass this discussion to a couple of very qualified individuals.
I'm interested to see what will come of it..