So I recently got a new Bosch Mass Air Flow sensor. They have completely modified it. The wires are gone and replaced with a circuit board. Bosch has removed the screen on the air filter side and has a new screen on the engine side. I cannot remember but I do not think I saw any cooling fins inside the MAF sensor. There are the two plastic bosses to secure the MAF sensor to the metal part which holds it to the body of the car but they are not threaded to secure it to the metal part. However, the two plastic bosses fit securely into the rubber bushings in the metal part.

 

That's odd. Wells and MicroTech have been making that same MAF for 10 years. It's called a TFT (thick film transistor) sensor instead of a hot wire sensor. I wonder if Bosch just finally threw in the towel on the MAF design they stole from Hitachi and started stealing from MicroTech instead. (Actually, there's probably a license/royalty fee involved).

It should look a little like this:



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I have the micro tech of the same design and have trouble with it.Brand new it only has 50 miles on it.I can put my bosch stock maf in and no trouble.Hoppfully you wont have trouble with the new design.The only reason i got it was everyone said it was better.

 

I tried the Wells unit some time back. My 89 TPI couldn't use it. I have no idea why but the stocker worked fine, the Wells gave my SES light some face time.

 

Ok, upon further inspection I do not see the Bosch name. It looked so much like the Bosch MAF sensor from the outside that I thought it was one. There is a sticker on the outside with the name BWD Automotive Group with a part number 57878. It looks like the one in the picture to the right. Sorry for the confusion.

I did not think the Wells unit was still available. People use to talk very highly of them. This one seems to have much better flow characteristics.

The engine was running very rough and when the mechanic tapped the old Bosch one the engine would run better inspite of the air problems I described in the other post.

 

Boss 355 that is what my 88 iroc did.I just wish I could figure out why.It didnt do it all the time tho.I also put the stocker in and was just fine no ses light.

 

The Wells / Microtech Maf reads more air at the same air flow/rpm as the Bosch does (hits 255, increases LV8 values, at a lower rpm), so this makes the engine tune run richer. It causes all kinds of open loop issues.

Thats why the Granatelli has a adjusting screw.

They are also temperature sensitive, rich/lean.

 

I too had a few SES lights when I had this new MAF sensor installed; however, as I fixed the vacuum problems documented in another post the SES light did not reappear. I know ours cars prefer Bosch sensors; however, people use to talk highly of the Wells unit. As my engine problems are corrected and during the hot summer driving months if any other problems with this MAF sensor occur I will update this post.

 

I just swapped in a wells the blm's went from, 160 idle and 128 at cell 10, to 132 at idle and 108 at cell 10. This is with just changing the maf and after letting the ECM do its learning. Also injector pulses increased 2 ful ms from 12 to 14 at wot.