Servicing mass airflow sensor

[zendriver]

Honestly, I’ve never touched one before, but the ‘O2 Silverado is starting to idle a little rough so I thought I would look there first. Previous owner had a K&N sir filter that probably didn’t help much.

Any tricks to it other than using the proper cleaner? Or, should I just go for it and replace it with a $30 Amazon special? The MAF cleaner alone is probably half that price. 200,000 miles.

Thanks

 

[AJHD]

I wouldn't replace it unless you need to. But yeah, the price for a can of MAF sensor cleaner is stupid.

I take mine out every once in a while and spray it off. They can get surprisingly dirty.

Note that some vehicles may have a relearn process for replacing or cleaning the sensor.

 

[Qualitytools]

Use the correct Mass Air Flow Sensor cleaner, follow the direction on the can. Also check your idle control valve, that will need to be cleaned also.

 

[bwringer]

Ergggghh... the aftermarket sensors are NEVER right, unless you just happen by sheer dumb luck to get one made by the same OEM in the same factory.

Yeah, it's worth carefully cleaning the MAF (easy) and the IAC and throttle body (slightly less easy) while you're in the neighborhood.

FWIW, MAF spray smells different than carb cleaner, etc., but it does seem to work well. The MAF is a delicate component with plastic parts, so yeah, I use the dedicated sauce. No clue what's actually in it or not in it compared to other spicy sprays on my shelf, but I'd rather not risk damaging an OEM sensor that was working up to a few minutes ago.

 

[zimman]

If it's not throwing a CEL I wouldn't fool with it. Run some fuel system cleaner through it and see if that clears it up. Is it time for a tune up? Are you using the correct plugs? Lot's of other questions. here.
Zim

 

[JerseyBoatBuilder]

Maf cleaner for the Maf and Throttle body cleaner for the thottle body if you are going to clean the IAC spray the throttle body cleaner in the IAC ports. If you remove the IAC just dont push in on the Pintle at the end of the IAC that is what controls air going through the ports.
It should only be two torx bits and an O ring on the IAC

 

[signcrafter]

Don't replace with some cheap knock off sensor, your problems will most likely only get worse. I get a few vehicles a year that owner had misfire so changed plugs which didn't help. So they go to amazon or ebay and buy a set of injectors for 40 bucks and replace them. Now it's running worse then before they started, but they always say new plugs and injectors so can't be them. I learned real quick to tell them I'll be putting OE plugs and injectors in before I start to diagnose. Most of the time just putting OE parts in fixes all their issues. Point being don't buy cheap junk for important parts because more times then not it will cause more issues and have you chasing your tail because you think it isn't the part you just changed.

Clean the sensor, clean the throttle body and IAC. I don't know if an 02 needs a relearn or not. Do you have a scan tool to read live data? I've also ran into a handful of issues caused by K&N filters, mostly owners not keeping them cleaned properly. This will throw off the MAF sensor.

 

[zimman]

Maf cleaner for the Maf and Throttle body cleaner for the thottle body if you are going to clean the IAC spray the throttle body cleaner in the IAC ports. If you remove the IAC just dont push in on the Pintle at the end of the IAC that is what controls air going through the ports.
It should only be two torx bits and an O ring on the IAC

Holy good call. IAC gets very dirty. Nice work.
Zim

 

[zendriver]

Don't replace with some cheap knock off sensor, your problems will most likely only get worse. I get a few vehicles a year that owner had misfire so changed plugs which didn't help. So they go to amazon or ebay and buy a set of injectors for 40 bucks and replace them. Now it's running worse then before they started, but they always say new plugs and injectors so can't be them. I learned real quick to tell them I'll be putting OE plugs and injectors in before I start to diagnose. Most of the time just putting OE parts in fixes all their issues. Point being don't buy cheap junk for important parts because more times then not it will cause more issues and have you chasing your tail because you think it isn't the part you just changed.

Clean the sensor, clean the throttle body and IAC. I don't know if an 02 needs a relearn or not. Do you have a scan tool to read live data? I've also ran into a handful of issues caused by K&N filters, mostly owners not keeping them cleaned properly. This will throw off the MAF sensor.

Yes, I do have a scanner that reads live data. What should I be looking for?

I swapped that filter out right after I got the truck five years ago, but it has seemed to start idling more rough recently.

 

[zimman]

Yes, I do have a scanner that reads live data. What should I be looking for?

I swapped that filter out right after I got the truck five years ago, but it has seemed to start idling more rough recently.

Forgot to tell you if you use a fuel system cleaner use "Berryman's B12" It's awesome and they've been around 100 years.
Zim

 

[zendriver]

Maf cleaner for the Maf and Throttle body cleaner for the thottle body if you are going to clean the IAC spray the throttle body cleaner in the IAC ports. If you remove the IAC just dont push in on the Pintle at the end of the IAC that is what controls air going through the ports.
It should only be two torx bits and an O ring on the IAC

Thanks I’ll look at that too

 

[signcrafter]

Yes, I do have a scanner that reads live data. What should I be looking for?

I swapped that filter out right after I got the truck five years ago, but it has seemed to start idling more rough recently.

Bunch of stuff to look at to try and get an idea. Misfire data to see if there are any misfires causing the rough idle. Fuel trims to try and see if there is a vacuum leak. MAF reading at idle should be around the displacement of the engine in grams per second. One other thing to look at would be the evap purge valve sticking open.

 

[jimindm]

If you can read live data, go on a test drive.

Get to a stretch of road that you can full throttle accelerate. You should see the load pid max out at about 100%.

I don't think there is an actual sensor for load, but it is a calculated value.

Every MAF I have ever doubted would never get close to 100%.

 

[toplessHO]

First problem is the K&N oil used on filter.
Dealership my son worked at wouldnt honor any induction related warranty if it had a K&N.
Too many owners put excess oil in the filter,which pollutes the MAF.

 

[charbar]

I've cleaned a million and one of those MAF sensors with brakleen. Even bending a Q-tip to reach in from the back side (since they have a screen on the inlet side) to give everything a little wipe. OH NO!!! INTERNET SAYS YOU CANT DO THAT!! Those particular MAFs can handle it fine. Save the 20 dollars for a can of MAF cleaner that you will only use four sprays out of and grab the brakleen off the shelf.


Flame on

 

[charbar]

Fuel trims to try and see if there is a vacuum leak.

You probably know this but OP might not.....leaking intake manifold gaskets are not uncommon on these engines (Im assuming he has a V8).

Will cause a rough idle when cold or all the time if they are leaking bad enough. Fuel trims will read high at idle and should return to normal when you run the engine up to 2KRPM or so and hold for a little bit.

I use BRAKLEEN to confirm then

 

[Buckaroo5]

Yes, I do have a scanner that reads live data. What should I be looking for?

I swapped that filter out right after I got the truck five years ago, but it has seemed to start idling more rough recently.

I service Toyota's and would not use anything other than an OEM (or OEM Mfr Denso) MAF so would clean it if possible rather than buying a cheap one. The rule of thumb is at idle, the flow should be equivalent to the displacement of the engine in liters. I use the CRC Electronics Part Cleaner which is not much more costly than brake clean. For the hot wire MAF's I clean, you definitely don't want to touch the wire and it is located around the corner from the temp sensor.

 

[richfinn]

Yes, I do have a scanner that reads live data. What should I be looking for?

I swapped that filter out right after I got the truck five years ago, but it has seemed to start idling more rough recently.

Basically you would want to see a distinct smooth change from idle to full load (preferably on a test drive). It might display in voltage or density (grams per second) or both on the scan tool.

I like to use a volumetric efficiency calculator on naturally aspirated engines, if your scan tool will graph data you can record the test drive and plot the results in the calculator at different RPMs to look for an under/over reporting MAF.

Volumetric Efficiency Calculator | OTC Tools

Performing a volumetric efficiency test can reveal the accuracy of a vehicle's Mass Airflow Sensor (MAF) as well as potential issues with the engine and can be the key to successfully diagnosing and fixing a vehicle.

otctools.com

Once you understand what the ECM does with the MAF data it's a little bit easier to understand.

 

[Wrench97]

MAF at idle should read close to the engine size IE a 5.3L will show about 5.4-5.6 grams per second, if it's dirty it'll read high air leak after the sensor will read lower.
I also have used a lot of brakekleen to clean them.
If need a sensor do yourself a favor and stick with OEM or OEM brand AC Delco in this case.
Short term and long term fuel trims when added together ideally are 0 but anything between -10 and +10 will run fine unless each bank is opposite ends of readings IE bank 1 is +10 while bank 2 is -10.
Positive numbers means the ECM is adding fuel to that bank negative numbers means it's taking fuel away.
Check trims at idle and 2000 rpm.

 

[zimman]

You still haven't said if there are any codes? Vacuum leaks would cause a lean code. MAF malfunction would cause a MAF code. Misfire's would throw a misfire code. If there's no codes it leans to fuel delivery right? Mostly because sensors don't mix well with fuel. Something about electricity and gas. LMAO There are none.
Zim

 

[zendriver]

You still haven't said if there are any codes? Vacuum leaks would cause a lean code. MAF malfunction would cause a MAF code. Misfire's would throw a misfire code. If there's no codes it leans to fuel delivery right? Mostly because sensors don't mix well with fuel. Something about electricity and gas. LMAO There are none.
Zim

No codes.

Runs and drive great, recently got 17.5 MPG. Just has a slightly rough idle, it did have before.

 

[zimman]

No codes.

Runs and drive great, recently got 17.5 MPG. Just has a slightly rough idle, it did have before.

Cool. I'd still run some Berryman's B12 through it. Probably clean up the idle. I've recommended it for years and actually put some in a customer's tank in the parking lot and within minutes, it was running better. I love that ****. LOL I'd use it in my beef stew if it didn't kill me. LMAO
Zim