MAF Walk Through

[sneeky]

I've searched the forums. Does anyone know of a walk through to do a cleaning on my MAF sensors? Also, how about a walk through on seafoaming with a vacuum line. Not sure which line to use and do I need to change the oil and spark plugs afterwards? Or is just the oil suffice? Wanted to seafoam using a vacuum line, but if involves changing my spark plugs I'd rather not.

[Nrw]

Unplug MAF

Remove the two tiny screws holding the MAF sensor

Gently remove MAF sensor

Spray with MAF cleaner

[sneeky]

Nrw thank you. I was hoping there was a walk-through with pictures since I'm schmuck when it comes to cars.

[stm25rs]

See attached pictures. Get MAF cleaner from your autozone/pepboys/whatever. CRC is the brand.

 

The picture of the sensor shows where to spray. You want to clean the bulb (green arrow), but part of the sensor is actually inside - you'll see the wires in there.

 

Follow the instructions on the MAF cleaner can, regarding spray distance/length of sprays. Let it dry before reinstalling; should dry very quickly, since you don't need to douse the sensor with cleaner for the cleaner to work.

 

Oh yeah, and disconnect your battery first, to prevent electrical hazard, and to clear the ECU's learned parameters. The car will idle a little funny when you restart it, but that's just the ECU relearning. My car doesn't always like to start on the first turn of the key, after clearing the ECU, don't worry if that happens to you.

[nouse4aname]

I've never disconnected it when cleaning on this one or prior cars. Just undo the two screws, flip it over, spray cleaner inside, screw it back in. I would also take a q-tip with some cleaner on it to the bulb gently if it's really dirty like a first time cleaning of a used car.

[sneeky]

I love this forum!

[Max Capacity]

I've never disconnected it when cleaning on this one or prior cars. Just undo the two screws, flip it over, spray cleaner inside, screw it back in. I would also take a q-tip with some cleaner on it to the bulb gently if it's really dirty like a first time cleaning of a used car.

 

 

This is how I do mine.

[covertrussian]

Here is how I cleaned mine, anything electrical I try to unplug, clean, let it dry, then reconnect it.

 

Make sure you use MAF cleaner only!

[sneeky]

Here is how I cleaned mine, anything electrical I try to unplug, clean, let it dry, then reconnect it.

 

Make sure you use MAF cleaner only!

 

Awesome! This is exactly what I needed.

[Max Capacity]

FWIW, After the second cleaning when I started the car I got 2 CEL's. both dealing with the MAF. I reset the ECU, all has been fine. Now once a year when I clean it, I leave it plugged in.

[sneeky]

FWIW, After the second cleaning when I started the car I got 2 CEL's. both dealing with the MAF. I reset the ECU, all has been fine. Now once a year when I clean it, I leave it plugged in.

 

If it's as easy as just taking a q-tip to it, I'll most likely leave it plugged in also.

[stm25rs]

FWIW, After the second cleaning when I started the car I got 2 CEL's. both dealing with the MAF. I reset the ECU, all has been fine. Now once a year when I clean it, I leave it plugged in.

 

Do you still reset the ECU when you clean it?

 

Here's my thinking on the subject, from a controls engineering perspective, with limited knowledge of ECUs/engine operation....somebody correct me if I'm wrong:

 

The basic principle of operation for the MAF is: there's a wire, heated at a constant current. Increased airflow cools the wire more, which decreases the resistance, which allows more current to flow.

 

As the MAF gets dirty, the sensor's reading will drift, and the ECU is (or should be) slowly adjusting to the sensor drift, which would affect fuel trims, which is why you should reset the ECU when you clean the MAF.

[nouse4aname]

Or just let it slowly adjust itself back.

[zanzabar]

Do you still reset the ECU when you clean it?

 

Here's my thinking on the subject, from a controls engineering perspective, with limited knowledge of ECUs/engine operation....somebody correct me if I'm wrong:

 

The basic principle of operation for the MAF is: there's a wire, heated at a constant current. Increased airflow cools the wire more, which decreases the resistance, which allows more current to flow.

 

As the MAF gets dirty, the sensor's reading will drift, and the ECU is (or should be) slowly adjusting to the sensor drift, which would affect fuel trims, which is why you should reset the ECU when you clean the MAF.

 

a dirty maf makes it run lean, so you dont have to clear it as it would just run rich for a little bit.

[JmP6889928]

Do you still reset the ECU when you clean it?

 

Here's my thinking on the subject, from a controls engineering perspective, with limited knowledge of ECUs/engine operation....somebody correct me if I'm wrong:

 

The basic principle of operation for the MAF is: there's a wire, heated at a constant current. Increased airflow cools the wire more, which decreases the resistance, which allows more current to flow.

 

As the MAF gets dirty, the sensor's reading will drift, and the ECU is (or should be) slowly adjusting to the sensor drift, which would affect fuel trims, which is why you should reset the ECU when you clean the MAF.

 

Your evaluation was pretty much spot on. To take it further so you know WHY it runs lean. The dirt acts as an insulator on the MAF sensing bulb/wire not allowing the wire to cool properly, which in turn tells the engine not enough air is coming in, which causes the ECM to reduce the amount of gas through the injectors, which does, as zanzabar says, cause it to run lean.

 

Lean, as we all know too well, is the kiss of death for boxer engines, ESPECIALLY for cylinder #4. If Subaru would just make 3 cylinders engines.......no more problems with #4....

[Max Capacity]

Do you still reset the ECU when you clean it?

 

 

 

 

 

No, only if I get a CEL.

[artard]

Here is how I cleaned mine, anything electrical I try to unplug, clean, let it dry, then reconnect it.

 

Make sure you use MAF cleaner only!

 

thanks, cleaned mine. all that gunk gone now.

[covertrussian]

Keep in mind the actual maf wire is inside (seen by looking at the bottom of the sensor). The one you cleaned is the IAT sensor.

[LatentWagen]

^ This. Everyone referencing cleaning a "bulb" has cleaned the temp sensor, not the MAF sensor. The MAF is a hot wire (or wires) that also gets gunked up, but it's located inside the tube. Be extremely careful cleaning it, and use a flashlight to make sure it's free of debris.

 

http://legacygt.com/forums/attachment.php?attachmentid=173439&stc=1&d=1390851760

 

Spray your MAF cleaner into the tube (red arrow above)...

[LatentWagen]

Went out and grabbed this pic, after hitting it with some CRC MAF cleaner.

 

http://legacygt.com/forums/attachment.php?attachmentid=221734&stc=1&d=1450812212

 

Hope this helps to clear up how to clean these sensors. I didn't use a Q-tip to clean mine (this is on an 06 WRX w/ 81k), but if you are gentle enough - and there is still debris after liberal spraying - then go for it.