Mass Air Flow Sensor (MAF) Available Anywhere? (Saab Version)

From the BOSCH Vehicle Application Guide:

Bosch 0 280 213 012 is used on:

Ferrari F50 1995 on
Ferrari 456 1993-1996
Saab 2.3 Lit. Turbo 1990-1993
Volvo 2.0 Lit 16V Turbo 1989-1994 (7 & 9 series)
Volvo 3.0 Lit NA 1990-1994 (960)


Bosch 0 280 212 016 (works on 348 with addition of CO2 resistor) is used only on:

Volvo 240, 740, 940 2.0 & 2.3 Lit NA & Turbo 1987-1998

 

Thank you much appreciated I will grab some spares

For the archives my challenge cars have these MAFs as stock

0280212018 348 challenge

0280213012 355 challenge

 

My 95 355 2.7 ECUs have the same 0280213012 MAF. I just bought one off ebay and that worked too.

So, it seems the Bosch Vehicle application guide is not complete. No surprise !

 

All info points to 0 280 213 023 as then correct MAF for 355 M2.7:

The BOSCH Catalogue

Vehicle Parts Database - BOSCH Air Mass/Flow Sensor 0 280 213 023 for FERRARI 512 TR 5.0

A post here

However, it is possible that 213 012 and 213 023 are interchangeable.
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348 MAF-s:
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Finally found the best alternative MAF for the 348 - BOSCH 0 280 212 022 (BOSCH 0 986 280 133 if factory re-manufactured). Saab p/n 7872385 & 8827461.

This MAF has identical voltage readings as the original 348's 0 280 212 018 and also has the CO pot. The only thing it needs is an additional plastic ring to the side that engages the filter box. I managed to get a pair of new 0 280 212 022 (from Sweden, last two that they had) and tested them on my car - runs perfectly.
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To add some additional information:

I just got off the phone with Tampa Volvo and they looked up the
part numbers of these for me:

Volvo 2.0 Lit 16V Turbo 1989-1994 (7 & 9 series) = 8251497 - $390 (looks like it matches bosch 0 280 212 016)
Volvo 3.0 Lit NA 1990-1994 (960) = 8251498 - $513 (looks like it matches bosch 0 280 213 012)

Pricing shown above is new and available in 24 hours from distribution in Atlanta.

 

More info:

This is the MAF off my car. Both sides identical. 1995 2.7 Motronic computers.
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More info on the 012 model
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Very cool. The number on my car (1990) is 280 212 022. So I just ordered 2 of 8827461 from here:

Airmass Saab 9000, 8827461
.
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Volvo 2.0 Lit 16V Turbo and 3.0 Lit NA use the same MAF - 0 280 213 012

MAF 0 280 212 016 (Bosch Reman. 0 986 280 101) is used on Volvo 8V engines (2.0 & 2.3, T & NA), p/n 3517020, 8251497 & 8602792

I noticed that some Volvo parts suppliers are offering "no name" substitutes for 0 280 212 016 (probably China made, $45 - &100 on Ebay). Original 0 280 212 016 is very hard to find but the factory remanufactured version of it (0 986 280 101) is still available, probably not for much longer.

 

I typoed the above post (#35), obviously my car has MAF 280 212 018.

And two of these (280 212 022) just came in the mail from Holland today, which I plan to try out this weekend. My car is running awesome as is so it'll be a nice comparison.
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The MAF does not have any "map" in it. It only provides one very simple signal to the ECU - a varying voltage, from approx. 1.5 V (at zero flow) to some 4.8 V representing the varying air flow through the MAF. What is special about the MAF is that it provides very accurate voltage signal representing certain air flow. The tolerance is some 0.02 to 0.05 Volt (two to five hundredths of a volt). If the MAF output voltage is just slightly out of the said tolerance, the engine would not run or would run rough. So there cannot be a situation where the engine runs fine but the MAF is not quite correct; it either runs or it doesn't.

 

If your MAF is dirty, it will send the wrong voltage without you even knowing it, unless it is REALLY dirty, or you have an air/fuel calibrated nose. So your engine would still run, but you MAY notice hesitation and harder starting. So saying it runs or it doesnt, isnt exactly correct. And at what point does one consider an engine running rough? Thats relative i'd say. Some people would freak out if their idle RPMs are at 950 instead of 1000, and some probably wouldnt even notice. Id like to know if there is a definitive way to tell if a maf is not working properly due to being dirty, or when it is not working properly due to pin readings. And how do you know if those bad pin readings arent there because of dirt remaining on the maf that sensor cleaner may have not removed?

 

I have tried a MAF that has just 0.12 Volt lower voltage reading (1.3 v.s. correct 1.42, at zero air flow) than the 348 MAF. The engine couldn't even start. So, the MAF output accuracy is quite critical. What I am trying to say is that, if you find an alternative MAF and the engine starts and runs fine (as with the original MAF), that MAF has identical voltage/airflow curve as the original, otherwise the engine would not run. If the MAF has a different voltage/airflow curve, it will be different enough so that the engine will not run with it. The MAF voltage/airflow curve is not unique to a particular Bosch number. There are MAF-s with identical curves but carry different Bosch numbers for other reasons/differences.

I don't think the hot wire of the MAF can really get dirty - any dirt is burned off during the self cleaning cycle. However, poor pin contacts in the MAF connector can reduce the MAF voltage output sufficiently to cause stumbling, sudden loss of power/acceleration, difficult or no start etc. Of course, a MAF output voltage can go out of accuracy due to age when it has to be re-built or replaced.

 

So, the best choice for replacing 348 mafs is BOSCH 0 280 212 022 With machined little plastic collar that it firs the airbox? If u dont find an oe one

 

I have tested the 0 280 212 022 in two ways:

1. Compared its voltage output readings with readings from a good (12k miles) 348 MAF 0 280 212 018. On a bench, I was able to simulate 3 points: no Flow, Flow 1 and Flow 2. I do not know what air flows 1 & 2 were (not important as I was just comparing 2 MAF-s) but the Flow 2 was quite high as it produced about 4.2 Volt which is fairly close to the maximum. At all points, the readings between the two MAF-s were no more different than 0.01 volt which is well within the MAF's normal tolerance.

2. Put two 0 280 212 022 on my 348 and the engine ran perfectly well, exactly the same as with the original good condition MAF-s.

Anyway, will have another feedback from Wade very soon.

 

I guess you can call it a map, or calibration. It is semantic. In the end, voltage value x has to stand for xx liters per second, and voltage value y has to stand for yy liters per second. The ECU uses those "calibration values" to calculate the volume of air it receives, compensates for air temperature, and gives the engine the amount of gasoline it needs.

So, I guess there is a map somewhere. So the map is in the ECU, not the MAF.

 

The MAF is actually a fairly simple analogue device. It has a wire the temperature of which is maintained at 155C by the electronic circuitry. The air flowing pass the wire tries to cool it down but the circuitry responds by sending more current through the wire to keep it at 155C. The higher the flow (higher cooling action) the higher the current sent through the wire. The electronics also produce a voltage signal that is proportional to the current it sends through the wire and this voltage is the signal to the ECU. The ECU has a "look-up table" (or something) programmed to correctly interpret the voltage signal received from the MAF and inject adequate amount of fuel.

The curve (on a graph) showing the MAF's output voltage v.s. airflow is called the "MAF Curve". This curve is not "tuned" to any specific engine. The MAF's (looking at one "family" or diameter) have a relatively small number of different standard curves designed to cover engines which require up to A Lit/min, up to B Lit/min etc. The engine manufacturer will select one of the standard curves suitable for the engine's demand for air and then programme the ECU based on that standard curve.

With regard to the CO2 Pot on the MAF, it is actually not connected to the MAF's circuitry in any way so it does not alter or "trim" the MAF's output signal. The Pot is part the ECU circuitry, connected between certain ECU pin and the ground. The reason why it is placed in the MAF is for convenience when adjusting the CO2 level (a remote ECU trim).

 

Just one clarification, an MAF signal reflects the mass flow rate of air, (Mass Air Flow hence MAF) not the volume flow rate. And mass is what is needed as the A/F ratio is a mass ratio. An A/F ratio of 14.7/1 means 14.7 kg of air to 1 kg of fuel.

 

I am an analog designer. I find this educational and fun. There must be an Opamp in that feedback loop.

 

Simplest case, a resistor in series with the hot wire. Constant voltage applied across the series pair. As the hot wire cools, resistance goes down. As a result of the constant voltage, current goes up (Ohms law). Current is related to mass (not volume) flow rate. ECU related current to mass flow and adjust injector pulse width to achieve desired A/F ratio.