td4 maf

Ok this is only my thoughts on the maf subject, the standard maf fitted to the td4 is a Bosch unit ,this is a very poor bit of kit and can deteriorate after 30k miles as it runs at 200 deg c it will either pack up[open circuit or not perform to its range, or get coverd in gunge, replacement bout£165 the pierburg will fit p /no 434220200 but you will have to shave 3mm of the case cost£55 ,the subject is complex and too deep for me to type out so if you are or suspect your having problems with yer maf and would like the answers [L R diagnostics will not pick up an outa range maf] only an open circuit.So go on e bay and type in td4 maf, and you can read and make your own mind up. . .

Er thanks tiny td4 its the same guy i thinks . . .

Ming,testbook is capable of showing a faulty air flow meter - esp when watching live data displays,out of range values go grey on the screen rather than black.Plus any good tech should have a "black book" of known good values to keep diagnostic time to a minimum.

Hi Ming and tinytdi,

Very good info of someone who installed and tested a Pierburg MAF.
What kind of thing is such a MAFAM he refers to? Is it an in-between box as I see when it is fitted with a Pierburg it substantially increases the values on his chart. Ciao.

eightinavee said:

Ming,testbook is capable of showing a faulty air flow meter - esp when watching live data displays,out of range values go grey on the screen rather than black.Plus any good tech should have a "black book" of known good values to keep diagnostic time to a minimum.

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Sure i take your point, but there is a lot of freelanders with the maf problem and 30-40k miles is about as good as the Bosch unit lasts, my point is that the pier burgh does a lot better job lasts a lot longer and is cheaper, L R know about the problem but have not addressed it, Willo the mafam is an add on ,for [1] Bosch mafs outa spech [2] for use with a pierburg as far as i can understand is not exact match as the Bosch and so re calibrates it, but I'm just starting to get to grips with this, so maybe some one has a bit more info on this subject. . .

hi there,the out of range grey band on t4 is no good for that test due to the pass band values being so different what we do regarding maf diag at a dealer, the test carried out is, using real time on t4 rev engine at a steady 3000rpm and if the value is between 510ish and 620ish then the sensor is ok,

if you are experiencing slugish behaviour and the mafs is tested ok then the probable cause will be the turbo modulator valve,

they are the 2 main causes, allthough there are still lots of other things that can create such behavoir but alot are alot more rare.

LR GUY said:

hi there,the out of range grey band on t4 is no good for that test due to the pass band values being so different what we do regarding maf diag at a dealer, the test carried out is, using real time on t4 rev engine at a steady 3000rpm and if the value is between 510ish and 620ish then the sensor is ok,

if you are experiencing slugish behaviour and the mafs is tested ok then the probable cause will be the turbo modulator valve,

they are the 2 main causes, allthough there are still lots of other things that can create such behavoir but alot are alot more rare.

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Like the VNT vanes siezing in the turbo,interesting that you actually know what values t4 will give on a sensor,most people that use testbook just moan about it,cos they would rather read fault codes and swap bits - rather than see what is actually going on.Do you do much live data work whilst the car is moving or just stationary in the w/shop ?

both really just depends on the complaint, sluggih problems can generally be diagnosed in the workshop but other complaints like ( my car hesitates at 70mph)and no stored fault codes req a little play with t4 mobile,

It must be nice having someone else having t4 mobile,I never took up that offer,still get asked to do quite alot with pre obd2 stuff - t4 is fine,I just use the Dell, connected through the docking station,(sat on the floor,passenger side) onto the cars port.
Bit of a shock when I got the letter from LR saying I need to upgrade as T4 is now obsolete - ouch !
Next year !

yes im glad i dont buy the equipment, they have just splashed out 20 odd grand on 3 new IDS diagnostic machines,

still waiting for them to be fully set up to use though

LR GUY said:

hi there,the out of range grey band on t4 is no good for that test due to the pass band values being so different what we do regarding maf diag at a dealer, the test carried out is, using real time on t4 rev engine at a steady 3000rpm and if the value is between 510ish and 620ish then the sensor is ok,

if you are experiencing slugish behaviour and the mafs is tested ok then the probable cause will be the turbo modulator valve,

they are the 2 main causes, allthough there are still lots of other things that can create such behavoir but alot are alot more rare.

Click to expand...

I've found that on the Rovers (L series in the 45 & BMW in the 75) the maf's deterioration mostly affects the signal in the very low flow range - from 1000-2000rpm.

So measuring it at 3000rpm can't be guaranteed to show up a dodgy one.

Usually you can tell by driving the vehicle - the loss of torque below 2000rpm is very noticeable.
Other signs:
a) most of the accelerator travel does nothing
b) having to rev up to pull away cleanly or hesitation and heartstopping delay if you don't.
c) engine vibration (tingle through the wheel on the 75, don't know about the Td4 though) & rough running.
d) if unplugging it improves performance

Some manufacturers are in denial, or is it the dealers and still fail to diagnose a faulty maf sensor. If it hasn't caused a fault code it isn't faulty seems to be the attitude.
Other manufacturers are on the ball - eg VAG & Nissan who offer replacements at vastly reduced prices.

Ron