Air Mass Sensor: Compatible Alternatives?

Hello, I decided some time ago to install a TDI 1Z engine from a 1993 Audi 80 into my 90s T2 BlueStar.
I actually thought I had everything after a long search. However, I've now realized that the mass airflow sensor (MAF) I have doesn't fit. Only 4 wires are available on the wiring harness, but the MAF has 6.
Control unit number: 0281 001 185 and 8AO 907 401 B.

'I didn't really want to buy a new Bosch part (number 0 281 002 072), and I was wondering if a Mass Air Flow (MAF) sensor with 6 pins would also work, or if a newer Bosch MAF sensor (which can be found a bit cheaper on eBay) that also has 4 connections would be compatible.'

I'm not completely clueless when it comes to technology, but 1. I can't find anything online about it (except for the pin assignments of the mass airflow sensor), and 2. electronics isn't really my area of expertise.

What also surprises me is that the LMM with the 4 pins is connected to the control unit with three pins, while the other one is only connected with 2.

I believe that if anyone can help me, it's one of you.



Greetings, Andi.

Hello T2-TDI!

If I'm not mistaken, the 1Z engine should have a mass airflow sensor (MAF) from Pierburg. I believe that Bosch MAFs were only installed in later models (but I'm not entirely sure).

If the Pierburg part fits your vehicle, then you can be happy for two reasons:
1. It's cheaper.
2. In my experience, it lasts much longer.

Regards,
Alex.

T2-TDI wrote:

What also surprises me is that the LMM with the 4 pins is connected to the control unit with three pins, and the other one is only connected with 2.

Hi Andi,

While I'm not entirely clear on which mass airflow sensor (MAF) you plan to install, both MAFs actually have 3 connections to the engine computer: 5 volts, sensor ground, and the MAF signal.
Both receive 12 volts from relay 109.
The old, large Pierburg unit also has a mass connector connected to the battery.

However, I would recommend installing the mass airflow sensor (MAF) that is specifically designed for the engine control unit (ECU), because the performance characteristics differ significantly, especially in the idle and low-load range.

Using the wrong mass airflow sensor (MAF), you could experience either significant sluggishness in the lower load range, or an excessively high fuel injection volume, which could consequently lead to problems during the emissions test.

I really appreciate that you have a response ready so quickly.
The mass airflow sensor I have is from Pierburg, it has 6 pins, and it only fits models manufactured in 1994.
I can forget about buying one from Bosch, as it costs €450 according to Bosch.de.

That's why I need an alternative.

According to my wiring diagram, the Pierburg unit only has two connections at the control unit.
Pin 1, control unit.
Pin 2: Sensor ground.
Pin 3: Power relay.
Pin 4 is free.
Pin 5: Ground.
Pin 6, control unit.

Do you have any detailed specifications for the Bosch fuel injector 0281002072, or do you have any idea where I might be able to find such information?

Greetings Andi

T2-TDI wrote:

I really appreciate that you have an answer ready so quickly. The mass airflow sensor I have is from Pierburg, it has 6 pins, and it only fits models manufactured in 1994. I can forget about buying one from Bosch, as it costs €450 according to Bosch.de. Bitte gib mir den deutschen Text, den du übersetzt haben möchtest. Do you have detailed data for the Bosch LMM (mass airflow sensor) with part number 0281002072, or do you have any idea where I could find such information?

Hi Andi,

Have you read the LMM technical article yet?

And which lambda sensor (oxygen sensor) is compatible with your engine control unit (ECU)?

I read the article some time ago.
However, I'm also stuck on this, because according to this description, both mass airflow sensors (MAF sensors) are powered by 12V, which should actually be controlled by the relay. According to the wiring diagram for my control unit, three wires from the MAF sensor go to the control unit, and one pin goes to ground.

'My engine is a 1Z model from 1993, and it uses the older engine control unit. The Bosch mass airflow sensor (MAF sensor) part number 0 281 002 072 is supposed to be used with this control unit. However, I don't have that Bosch sensor; I only have a Pierburg sensor.'

I would be happy to send a picture of the wiring diagram for the control unit to anyone who can help me.

Thank you and greetings.

Andi.

Hello T2-TDI,

'I'm not entirely sure, but you probably have almost the same engine as I do, and therefore an airflow sensor that uses a potentiometer connected to a deflectable pressure flap(?). This would also explain why your airflow sensor doesn't receive power from relay 109. Unfortunately, I had some parking issues this week and I don't have my repair manual with wiring diagrams, nor my tools, with me. So, I won't be able to provide more information until Thursday, unless your problem is solved by then.'

Regards,
Michael.