Mass air flow meter

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Mass air flow meter

Postby tangoman » Sun Jan 24, 2016 2:50 am

Alfa 156 twin spark come into my work shop with bad flat spot when cold the car had a new Air flow meter just a few hours old and was ask to see why it had bad flat spot so check for codes no codes so set up the 02 sensor and TPS and airflow PID on scan tool and went for a drive give it full throttle and the 02 went lean so I know it needed more fuel I knew it had a new air flow meter so I check fuel pump and pump flow was ok ?? ok let check the new air flow meter .

The new air flow meter went to 4.454 volts so looks like the new air flow meter was ok ? so I scope a few Alfa 156 air flow meters before and had a look at the my Pico library yes good air flow meters go to about 4.4 volts with motor hot ?
but then I had a good look at the time it took to get there and wow the new air flow meter was a lot slower to get to 4.4 volts so I had a good look at the new air flow meter and did not see Bosch on at any where so I called the work shop they give me the job and ask he where did he get this new air flow meter from he said it was some after market thing and was told it was just as good as the Bosch one ! ok I ask him if I can put in a new Bosch air flow meter because it looks like on the picoscope your new aftermarket air flow meter is just a bit to slow

so the next day I get a new Bosch Air flow meter and bingo car run great again

so next time you get a car with a big flat spot always scope before and after you clean the air flow meter so you know what a good one look like if you just clean the air flow meter and never scope then you will never know when you have a bad one if I did not have a know good Alfa 156 air meter in my pico scope library it would had made my job very had to see the so call aftermarket air meter that was slower then the new Bosch air meter ..
Attachments
Screenshot (15).png
New Bosch air flow meter
Screenshot (18).png
New aftermarket air flow meter see how much slower it take to go to 4,4 volts
DSCF2889.JPG
Alfa 156
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Re: Mass air flow meter

Postby Fat Freddy » Sun Jan 24, 2016 7:26 am

Yes. You always get nervous when new parts are involved.

I recently had a similar issue with a MAF on a Mazda. Brand new, same part number as OE, same manufacturer from a supposed reputable dealer.
I was convinced it was the MAF but not enough to splash out nearly $400 on a new one. So I sourced another genuine second hand one. Performance was increased massively.
On closer inspection things didn't quite add up. The brand new one on first look was identical and the numbers matched. But each digit was slightly chunkier. Each corner slightly radiused. The finish was slightly smoother, the detail not quite as sharp. Just like if you make a mould of something, the same but not. I couldn't prove anything but I had my suspicions.

I did have pics to put up sometime but didn't have the time but now... 8) :D . If I find them I'll post them up.

cheers
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Re: Mass air flow meter

Postby Fat Freddy » Mon Mar 21, 2016 4:28 am

Suspect faulty new v's second hand.

Here are the images. Sold by a major (you will know the name) independent Australian EFI parts supplier as a genuine part at genuine prices. Does not sell Chinese copy's. If I find the psdata files I'll add them as well.
Bad Maf 1.jpg

Bad Maf 1.jpg
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Maf.jpg
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Re: Mass air flow meter

Postby STC » Tue Mar 22, 2016 10:59 pm

I always scope Maf alongside Pedal Position. Pedal sharply to the floor and watching MAF reaction to pedal signal is a good benchmark as to Maf condition / reaction time
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Re: Mass air flow meter

Postby xandro » Fri Sep 02, 2016 12:00 am

tambem tive aqui um problema parecido com o seu em um mx3 , fluxo de ar lento . deixa a marcha lenta muito ruim mesmo :D :D :D :D :D :D :D :D :D :D :D
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