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

Yes, it is the mass of the air. I put litres for simplicity of the description (flow is usually expressed as volume/time). The voltage output represents the rate of attempted cooling of the hot wire. One litre of denser air will cool the wire more than one litre of thinner air so the voltage represents the mass (like kg of air per minute). There are other functions of the MAF's circuitry (like compensation for the temperature of the incoming air) that I left out.

 

I disagree with most of the above.

Starting and running fine is definitely not verification that a maf has an identical output vs airflow. A vehicle can run quite well with the maf output even over 20% off, especially after fuel trims have learned.

The only way to know if the output curve is in fact identical/correct is to verify this on a test bench. (as mentioned in your post 44 is good but ideally at more points) Second to that, verifying fuel trims are correct at several different airflow rates would be a good indication but simply starting and running is not.

Also, I have seen a dirty maf sensor result in up to 20% positive fuel trims at part throttle and (on vehicles that reference it at WOT) 1.5 points lean at WOT. Cleaning the sensor with electrical contact cleaner brought fuel trims to zero correction and also corrected WOT air fuel ratio.

Aside from being incorrect or dirty these also can fail with time, almost always as a reduced output resulting in a lean condition/positive fuel trims.

 

The basic principle described is correct. Just to add - in the case of the type of Bosch MAF's we are talking about, the varying current through the hot wire (translated into varying voltage by the MAF's electronics) is not the current as naturally dictated by the cooling of the hot wire (via the Ohm's law) as the wire does not actually cool-down. It is the electronics that send higher current through the wire to keep it at 155C (temperature in the case of the 348's MAF). So, there is a continuous "fight" between the cooling action of the air and the electronic circuit response over the 155C.

 

MAF 0 280 212 017 (Saab) has voltage output readings (measured at my 3 points) about 9% lower (at each point) than those of the 348's 018. The engine would not even start; well - started with a fairly good sound for only a second then coughed a lot and died quickly. I gave the ECU-s a few more chances to "learn" but they did not.

Yes, of course. Before testing the alternative MAF-s on my 348 (Volvo's 016 and Saab's 022) I bench tested their voltage outputs. Both showed readings that were no more than 0.01 / 0.02 volt different from the readings of the 348's 018.

 

Perhaps other types of MAF-s. The 348 MAF (and many other similar Bosch MAF-s) heat-up the hot wire to 1,200 C during the self cleaning (burn-off) process. This should not allow dirt build-up to such an extent.

I observed this burn-off process once. Ran the engine without the air cleaner box, revved it past 4000 rpm, switched off and ran like hell to the engine - the MAF's wire lit-up like a bulb for a second or two.

 

Inside, both MAFs look exactly the same except the newer one (SAAB) still has some flash from the mold/forming. The one from the 348 seems to be finished better, possibly to improve the airflow? These views are downstream.
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The intake on both look exactly the same, wires and all.
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So here's what I did this evening:

1. Disconnected the battery cable for 10 minutes (or so)
2. Reconnected the battery, and started the car using the ECU learning procedures
3. Went for a spirited drive, car ran perfect
4. Back home, pulled the codes and received 4444 only on both ECUs (i.e. no codes)
5. Removed the old MAFs (348 018) and installed the new ones (SAAB MAF 022)
6. Did NOT set the ECUs to "relearn" anything, just fired her up and went for another drive.

Well, the car ran awesome and felt as if the throttle response was better as well. The drive was a mix of stop and go plus some "drive it like ya stole it" runs just to trip a code or something.

But everything was perfect.

Back home I pulled the codes; 4444 on both sides (no codes).

I think I'll leave these new MAFs just where they are.

Thanks Miroljub!
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Well, this is why the MAF, when bought as a genuine Ferrari part, costs much more. Polishing the venturi is very expensive.

 

A quick look this morning of those offering the Ferrari MAF (prices are for one each):

$875 new
890 British pounds new
$950 rebuilt
$700 used

I paid 99 Euros each.

 

I also noticed that Ricambi are now offering a MAF for 348 at the mentioned price but the MAF shown on the picture does not have a CO2 screw (?). Perhaps another Bosch equivalent to 0 280 212 018 but without the CO2 Pot, or perhaps another brand (not possible to recognise the writing on the MAF cover).

 

Hey Guys!

Interesting to read what you found out. I just bought a 1990 348 ts from Texas with a engineburn Damaste. Although the MAF are a total loss. After reading this Chat i found a Data-sehet for the "22s" http://www.farnell.com/datasheets/23599.pdf

 

Hey Guys!

Interesting to read what you found out. I just bought a 1990 348 ts from Texas with a engineburn Damaste. Although the MAF are a total loss. After reading this Chat i found a Data-sehet for the "22s" http://www.farnell.com/datasheets/23599.pdf

 

thanks for posting the update

 

That's great info, Paul. Please post a followup once you've run the second rebuilt one for a while.

 

How in the world did I miss this thread?

Awesome info guys!!!!

 

Hello,

Does anyone knows where to buy a 0280212022 at a reasonable price?
I tried the links in the previous posts and the part was no longer available. Finally I managed to find one in Russia but it was lost in shipping and the vendor don't have another one.
He offers 0280212014 as a replacement, any idea if it will work ok?

Many thanks!