Rejuvenating a Bosch Motronic Air Flow Meter

Here's a video description of refurbishing a Bosch AFM for a Porsche 924S/944. On a wide open throttle run, it would go flat at ~2000 rpms before getting itself together up towards redline. This is a good thing to check if you're experiencing any kind of random hesitation and have ruled out the obvious stuff, like vacuum leaks, bad plugs/wires/distributor points, oxygen sensor, ect.

This same repair concept probably applies to any other barn door-type AFM, only getting at the inner workings will be different.

This info was mostly from http://www.the944.com/ under "Air-Flow Meter"

Category:

Autos & Vehicles

Tags:

• Porsche
• 944
• 924S
• Bosch
• Motronic
• DME
• AFM
• air
• flow
• meter
• fix
• rebuild
• refurbish
• barn
• door

[nyko944]

I have a question about the motronic AFM,I do have the same barn door style like yours but with the star screw,other than that,my main issue is my vehicle has some odd sputtering when i raise the rpm,the engine is in great shape when i bought just 7 days ago,i have added new spark plugs and a blaster two MSD coil,new filter and spectre intake,thought after all this would change, it is probably my afm?what do you think?

[GFVagent007]

@nyko944 Check the distributor cap/rotor if equiped. Check for leaky spark plug wires arcing out by looking for stray sparks in the dark. You can also test the airflow meter for proper operation by measuring the voltage signal sent back to the ECU for smoothness, or hook it up to a voltage source (depends on the car) and measure the output (see link in vid info). Sounds like either a misfire or running rich. Try a good injector cleaner, check engine and air temp sensors, fuel pressure, O2 sensor

[newunborn]

i have a 84 e30 bmw 318i it looks the same as your video umm there is a star shape bolt on the top front can you adjust it from there

[GFVagent007]

@newunborn Top front of the AFM housing? Internal or external to under the black cover? It could be the air bypass adjustment for setting the mixture at idle (which is also how you adjust CO emissions at idle) if it is not inside the black covered compartment. The air bypass is near the intake side, often under a steel block off plug. Basicly, do not change anything that looks like it will change the rotational indexing of the wiper contacts in relation to the shaft.

[LittleModig]

hey cool how to .... clip.thankx. I got one question on this older model Bosch AFM.basically on the instructions your talking about at 3.0mints your talking a bout the ground wire that was not done on the older model Bosch AFM, where would I sourer the wire to I guess form the arm to ?????I don't know other than the Alum box?help please.....also what did you do for rerouting the arm on the new track of the ship board???? thank you for your clip....

[GFVagent007]

@LittleModig the added ground strap would need to be soldered to somewhere on the arm itself and the other end to the copper contact that reaches to the top center of the shaft. It's for a cleaner signal than the rotating contact alone. I would be sure to use high quality high strand count wire so it won't break down from flexing all the time. You basicly want to relocate the arc of the wiper, so raising the arm and bending the creases tighter or lowering the arm on the shaft and stretching them

[TestaMetaDeth]

thanks man!!!!

[benautoparts]

I need to watch this when I have time.

[MkoneEscort]

very helpful vid, my Mazda 626 turbo 88' has the older bosch AFM, and it has done 289,000 km's. I will move the wiper arm too a new track now to see if i can fix a unknown running problem my car has (hesitates just when throttle is applied whilst driving in any gear and idle is very poor indeed, fuel ecconomy is bad also- 350 km from 40 litres is bad)

[madmax160764]

Thank man, Have a e30 318 and i just find out why my engine didnt start, the mass air flow door was stock open and by the way i adjust the resistor like you did,. Now the engine run great ! Mad

[gearheadjacobson]

You rock so much my friend! Thank you for this video, saved me 80 bucks. :)

[tenwierdufos]

Awesome, thanks for this, im going to give it a go tommorow and see if it removes my flat spot :) Dont think its been off the vehicle in 19 years so probably is worn out!

[DEWESNE]

My '85 735i has the symptoms you describe... great over about 2500rpm and crap elsewhere (where I drive 90% of the time). The vid is helpful showing exactly how the adjustment is done, not just a typed paragraph.

[osiz1]

why the hell so slow are you talking???