850 and S/V70 TDI D5252T - DIY MAF (Mass Airflow) repair
 

It works only for MSA 15.7 (not MSA 15.8) cars which have a mechanical MAF - Mass Airflow sensor.
In those cars, it is actually a VAF - Vane Airflow sensor.

The repaired MAF lasted for 8 years and 8 months with 97.000 miles driven and it was replaced by another MAF repaired in the same way :-)

First eight pictures speak for themselves - How to open the MAF carefully.

After opening, clean it from the small debris which might have fallen in and also clean it with some good contact spray and let it dry completely. Would be best to leave it overnight somewhere dry and warm.


Pictures 9 and 10 show how the resistance stuff on the board has three wear marks cut by the constant moving copper part with three little contact "heads".

So, when the wear marks become to deep, electric signal becomes absent or distorted which results in erratic behavior of the MAF and the ECU receives wild signals which make the engine go crazy and sometimes make it go into limp mode, lose power or produce very rough idle, black smoke etc.

So, the idea is to get the healthy part of the resistance stuff go beneath the moving copper part.

It is achieved by moving the board just 1 mm up north.

That is shown on the picture 11. Marked red is the 1 mm free space where the board must be moved all the way to the housing.

Marked yellow are the three screws which need to be removed and then those screw holes on the board must be slightly enlarged to allow the board to be moved 1 mm upwards north and firmly tightened to keep the little board in the new position.

And that's it. Moving copper part will now have contact with the healthy resistance stuff and the signal to the ECU will be right and pure.

Close the MAF plastic cover with some non acidic silicone (or similar) and let it dry before installing in the engine bay. Also clean the MAF connector contacts with the contact spray.

Dirty MAF connectors can give you headache :-)

Enjoy your new MAF :-)

Hope it will help all faithful 850 and S/V70 TDI owners :-)

Excellent, Hal, thanks for taking the time to document! This needs to go in the 850/x70 S1 Articles before it gets lost.

Do I have to do it? Or the moderator will do it?
Tnx.

It needs to be moved by a moderator - if a mod reads this, can you move this to "articles" please? It's really useful and will be difficult to find otherwise.

By clicking on the report icon https://www.volvoforums.org.uk/image...ons/report.gif the moderating team will receive a notification. I've sent them a request.

I thought of doing that, but it says only to be used for abusive or spam posts, hey ho, hopefully they won't mind. :teeth_smile:

I asked them nicely :tongwink:

That post is certainly abusive for all the dishonest repairmen and dishonest stealerships which made heavy profit while "repairing" that MAF :rolleyes:

This fix price is very close to zero :angel_smile: