PIERBURG MAF SENSOR INFO
Pierburgh are a German company that manufactures various parts for motor vehicles, both as oe (original equipment) and after market applications. Their products tend to be cheaper than Bosch equivalents whilst in many cases being of superior quality.
All maf sensor manufacturers produce many versions to suit particular engines, so whilst they may only appear to differ by the connector design and the presence or absence of an air temp sensor, they are calibrated differently.
See graph below which is for various Bosch mafs showing quite a wide variation in signal versus mass air flow. For example, if you fitted maf type 5 to a smaller engine that used maf type 1, the signal would never reach the expected value at 4.5volts. In fact it would barely reach 3v, giving very poor performance.
This means that you cannot just fit any maf to any engine and expect good results. You may get some sort of a result but both performance and mpg will suffer over much the the rpm range even if the car is actually driveable.
A classic example of this is the Pierburgh 7.22684.090 maf which is specified by Pierburgh for use on over 100 BMW and Mercedes vehicles. It is NOT specified for the 75/ZT/TD4 versions of the BMW engine and buyers & sellers should not assume that because the engine is a BMW one, a BMW maf will work. Don't take my word for this - check Pierburgh's parts website
ROVER, MG & FREELANDER TD4 MAFS
The standard Bosch Mafs fitted to the later L series & BMW engined 75/ZT & TD4 are expensive - about £200 + vat and delivery = ~£250. They become unpredictable and temperamental and are easily damaged by moisture & oil contamination. So if your car has done over 30-40k and the performance &/or fuel consumption has worsened, the maf is probably to blame.
Pierburgh recently brought out a new maf (7.22701.090 which is for many Fiats and also the L series Rovers) - it doesn't need a Digimafam, although many owners say that the 070 maf + a Digimafam gives a better result, and I also recommend this option is any other tuning is being undertaken. They also launched the 7.22684.11.0 for the 75/ZT & TD4 which sells fro around £130. Better results are also to be had with a DGM2 + 070 maf for around the same cost.
The Pierburgh 070 maf we supply is an original Mercedes part and not a cheap clone and was chosen for its excellent value for money. This means it is NOT calibrated for any Rover, MG nor Freelander. For this reason, to make it compatible, you need either a Digimafam DGM1 (L series Rover & MGs)or on the the 75/ZT/TD4, a RonBox 2A or DGM2. (obviously, with a RonBox 2, the maf switch must be on for the recalibration to work.) It also lacks and IAT which is therefore provided by the Digimafam or RonBox 2 cable.
The photos show the Bosch & Pierburgh mafs - L series etc (left) & 75/ZT/Td4/BMW/VAG (right).
The screw holes are offset so you can only fit it the correct way round.
Mechanically & dimensionally they are identical so fit the existing housing without any mods being needed.
The sensor is held in using two security screws. These will be either security Torx 6pointed or 5pointed. We now stock the hard to find 5pointed type for under £10
(NB. The Bosch unit is supplied as the complete air mass meter i.e. the sensor plus its duct, whereas the Pierburgh maf is just the sensor as shown above. It therefore replaces the Bosch sensor without the duct needing to be removed.)
Pierburg on left, Bosch (Rover) on right.
Both output about 1v engine stopped and the PB reads about 2v and the Bosch 2.2v engine idling & EGR closed.
BMW MAF SENSORS:
Some have a 5pin Bosch maf and Pierburgh's 0.722684.090 is listed as a replacement. BUT the car must be taken to the dealer for an ecu update. Alternatively, fit a DGM2 or Ronbox 2A.
Many other models use a 4pin pulse type maf and so you cannot use a DGM2 nor RonBox 2 with these, nor change to the 5pin type.
WHY CAN'T I LEAVE THE MAF UNPLUGGED?
Some owners have been advised that its okay to just leave the maf unplugged. This is not a good idea for the the following reasons:
a) Not only is there no air flow measurement, but no intake air temp sensing either so the ecu defaults to -5C. This results in over fuelling, especially in warm weather leading to poor fuel consumption and lump running.
b) The lack of air temp sensing means the timing is not optimum as the ecu uses the IAT to adjust the injection timing.
c) The ecu's overrun fuel cut off feature may be disabled, also making fuel consumption worse and engine braking worse.
d) Performance is worse: A higher revs on the L series - the engine won't rev past 4000rpm and on the 75/ZT/TD4 there is a stodgy, choked feel probably due to the overfuelling.
A WORD OF WARNING: Beware the non Bosch mafs and suspiciously cheap Bosch ones - years of feedback from owners who have tried these confirms that you get what you pay for. So its a 100% genuine, unopened Bosch maf for which you will pay ~ £200+ vat or a Pierburgh with Digimafam or RonBox 2in my view.
Finally, many thanks for Pierburg subsidiary Motor Service International for emailing me the data sheet.
ROVER 75, MG ZT AND FREELANDER TD4 OWNERS:
I would draw your attention to the requirement to have the MAF SWITCH DOWN (ON) when the Pierburgh maf is fitted, and normally you would need to use the higher maf compensation - ie settings 6 to 10.
The reason for this was given above and is repeated here:
The Pierburgh one we supply is an oem Mercedes part and not a cheap clone and was chosen for its excellent value for money. This means it is NOT calibrated for any Rover, MG nor Freelander TD4. For this reason, to make it compatible, you need either a Digimafam DGM1 or on the the 75/ZT/TD4, a RonBox 2A or DGM2 which recalibrates it.
If you try to use it alone, or without the RonBox 2's maf switch on, the performance will be very poor below 2500rpm - just like a very weak Bosch maf in fact.