How to reset Air Mass Flow (MAF) sensor adaptives? Topic is solved

GDiode · Post by **GDiode** » 02 Mar 2017, 16:36

I did some research when my 2004 V70 NA started stalling after the engine warmed up and then coming to a stop. I put some additive in the gas tank when a thread talked about water in the gas. That didn't help. I then cleaned the MAF, unplugged the battery and held the cables together. That didn't help I then bought a new Volvo MAF unplugged the battery for 10 minutes and went through a series of steps like making sure all the accesories were off, turning the key to position 1, ect, that I had found on a Forum. That didn't help.
Is there a way I can reset the adaptives without taking it to a shop that has VIDA or something else. I've driven it about 300 miles since replacing the MAF. Will the computer reset the air setting on it's own after a certain number of miles? Thank you, Shannon.

Post by **oragex** » 02 Mar 2017, 17:18

Not sure the MAF is the issue. First make sure the butterfly valve on the throttle body is clean on both sides.
Revs dropping when coming to a stop may also point a leak near or at the brake booster.
To reset the car ECU I keep the key in ignition Pos II then disconnect the red battery cable for several hours. The fan speed knob on the CCM module won't have any light and turn at full speed when the ECU has reset. Same thing key in Pos II when reconnecting the battery.

Post by **JRL** » 02 Mar 2017, 20:32

There are none.
Nothing TO reset on a MAF
If a new one didn't help .... look, elsewhere!

Post by **abscate** » 03 Mar 2017, 04:02

Check your short term fuel trim or a removal-inspection of vacuum hoses looking for leaks.

Check fuel pressure regulation on these cars, check fuel pressure at the rail.

GDiode · Post by **GDiode** » 04 Mar 2017, 17:27

Thank you guys for your responses.
I hadn't mentioned in my original post that along with the stalling it is making a high pitch whine also when the engine warms up. That along with the stalling and the slight "diesiling" at stops is what lead me to the post about the MAF needing to be replaced. It almost seems like there is to much pressure inside the engine when it's idling.
Abscate, I'll check the fuel pressure at the rail. What is an acceptable PSI?
Oragex, I'll see if the butterfly valve is clean. Would a leak at the brake booster show as the brake fluid level dropping? Because it has been consistantly full.
Thanks,
Shannon

Post by **MadeInJapan** » 06 Mar 2017, 18:37

Then clogged PCV? Do a glove test...put a latex glove on the oil inlet on your engine and start your engine and let it idle. See if the glove blows up...it shouldn't. If it does you have positive pressure in your engine that needs to be taken care of with a PCV over-haul.

Post by **abscate** » 08 Mar 2017, 04:31

GDiode wrote:Thank you guys for your responses.
I hadn't mentioned in my original post that along with the stalling it is making a high pitch whine also when the engine warms up. That along with the stalling and the slight "diesiling" at stops is what lead me to the post about the MAF needing to be replaced. It almost seems like there is to much pressure inside the engine when it's idling.
Abscate, I'll check the fuel pressure at the rail. What is an acceptable PSI?
Oragex, I'll see if the butterfly valve is clean. Would a leak at the brake booster show as the brake fluid level dropping? Because it has been consistantly full.
Thanks,
Shannon

P2 pressure should be 50 psi and there is a spec for holding a certain pressure at shutoff too

Search of "P2 fuel pressure specification "

viewtopic.php?f=9&t=75015&p=398621#p398621

GDiode · Post by **GDiode** » 09 Mar 2017, 17:23

I took the oil filler cap off and it took a little more strength to open due to a vacuum that had been created. When the vacuum seal broke on the cap it made a whoosh sound and the high pitch whine went away. I put the glove on and it sucked the glove in. I believe the engine dieseling went away as well. What would cause this? If the PCV is clear would a severely plugged catalitic converter cause the vacuum? Would it also cause the stalling when the whine starts. It runs totally fine at idle and driving until it warms up enough to create the whine? Any ideas? I still haven't checked the throttle body butterfly valve to see if it's gummed up because I assumed I would need a new gasket when I put it back on. Any ideas?

Thanks, Shannon

Post by **JRL** » 10 Mar 2017, 08:42

That is a bad PCV (breather system) it needs to be renewed.
N/A's whistle when clogged up
I have replaced several of these, I don't know why non turbos whistle when clogged up and turbos don't but they do...(fact of Volvo life).
You need to bite the bullet, do a complete breather with all new parts and hoses and at that time clean the throttle (carefully)

GDiode · Post by **GDiode** » 10 Mar 2017, 16:12

How accurate is the glove test? It sucked in the glove really fast. The sound does sound like its coming from the front of the engine under the injectors which could also be from the oil trap part of the PCV. Today as it was making the whining sound I removed the oil filler cap with the engine running and the noise went way put the cap on it immediately comes back. If its the PCV cool I can handle that but how often does the glove test not work? Could it be a NA versus turbo thing?

Thank you,
Shannon