Clean That MAF Sensor -- Today!

[tvpierce]

Brief history: I've had my '02 Sport for about 3 years/25K miles (now at 150K). The engine performance has always been a bit sluggish -- weak throttle response, low power at high RPM, etc.
I just chalked it up to the 3.4 engine being a turd. Even the downshift behavior was odd. I couldn't get it anywhere near redline even when I floored it. Made hauling a trailer uphill a chore. I thought maybe the kickdown cable needed adjustment, but I never got around to investigating it. (does this electronic transmission even have a kickdown cable?)

So this week I get a CEL. Its throwing a P0171 code, and exhibiting slight hesitation on acceleration -- it's never done any of this before. My research on this forum leads me to the MAF sensor needing a cleaning or replacement.

It took me longer to walk in the parts store and buy the can of spray than it took to perform the service. Remove the connector, remove two screws, pull MAF sensor out of intake tube, spray BOTH sensors -- the "bulb" you can see, and the wires that you have to search for. Re-insert MAF sensor, re-install two screws, re-install connector, you're done! If it takes you five minutes start-to-finish, you're dilly-dallying.

Completely transformed the engine. No more hesitation, crisp throttle response, accelerates hard to redline.
Just did this last night after work, so don't have MPG numbers yet. I've been consistently at 15-16 mpg around town since I've owned it. We'll see. (I'll update after a couple tanks)

The takeaway: Don't wait for a CEL like me. Clean you MAF sensor as preventive maintenance. Super easy & inexpensive. Might help... can't hurt.

 

[JayRolla]

Adjusting my stretched throttle cable, lockdown cable, maf cleaning and oem plugs/wires transformed my truck. I'm like you. Took me 5 years and a hesitation to finally do it.

 

[JoeT4R]

[MENTION=159439]HMGT4R[/MENTION] I think we should consider doing this just for the sake of cleaning it...

 

[99problems]

Adjusting my stretched throttle cable, lockdown cable, maf cleaning and oem plugs/wires transformed my truck. I'm like you. Took me 5 years and a hesitation to finally do it.

Excellent suggestions. Adjusting the slack on the throttle and cruise control cables really helped with response time(s). I had to get in and clean the MAF sensors after I switched from stock intake tube to the airaid tube; apparently the difference was enough to trigger the code. Whole process was much easier than I expected.

 

[octanejunkie]

Good for you OP

Cleaning the MAF is recommended at the air filter change interval.

If it weren't such a PITA to get the sensor out I think people wouldn't ignore it as much as they do. Wonder why the orientation couldn't be at 12:00 or 3:00.

Would love to see a write up of someone removing the slack from the cables mentioned.

 

[024rnrSport]

K&N filters and MAF sensors do not get along well. One of my first mods was to put the k&n where it belonged... in the garbage can (sorry Tom! )

 

[johnbyebye]

Speaking of throttle cables, there seems to be a rubber bushing on my accelerator that is completely worn out, adding to the slack. Does anyone know this part number?

 

[johnbyebye]

Good for you OP

Cleaning the MAF is recommended at the air filter change interval.

If it weren't such a PITA to get the sensor out I think people wouldn't ignore it as much as they do. Wonder why the orientation couldn't be at 12:00 or 3:00.

Would love to see a write up of someone removing the slack from the cables mentioned.

http://www.toyota-4runner.org/3rd-g...e-response-better-shifts-throttle-cables.html

 

[fwankie]

I just did a new air filter, cleaned the MAF, and cleaned the throttle body all at the same time this past Wednesday; prior to a 1,200 mile road trip to North Carolina. I blasted the "bulb", and the sensor as a whole with MAF cleaner..but can you explain a little more about the "wires you have to search for"? I have a feeling I may have left that part out of the process.

Getting ready to probably knock out the deckplate mod and the ISR mod here probably over the weekend to go along with it all.

 

[BN-2B]

Check the MAF

Chasing codes led me to clean the MAF several times.
I even got a back-up off eBay to swap it out.
Then I learned how to test the MAF :

| Repair Guides | Components & Systems | Mass Air Flow Meter | AutoZone.com

Now I know that I'm cleaning something useful.

 

[tvpierce]

I blasted the "bulb", and the sensor as a whole with MAF cleaner..but can you explain a little more about the "wires you have to search for"? I have a feeling I may have left that part out of the process.

Check out link: (scroll down a little, and there are six pics that are literally the steps you need to take... including putting a Phillips bit in vice grips if you don't have a ratcheting driver. Also, you don't need pliers to remove the connector.)

Toyota Maintenance: Tacoma and 4Runner 30K Mile Service

 

[phattyduck]

I just did a new air filter, cleaned the MAF, and cleaned the throttle body all at the same time this past Wednesday; prior to a 1,200 mile road trip to North Carolina. I blasted the "bulb", and the sensor as a whole with MAF cleaner..but can you explain a little more about the "wires you have to search for"? I have a feeling I may have left that part out of the process.

Getting ready to probably knock out the deckplate mod and the ISR mod here probably over the weekend to go along with it all.

The bulb is only a temperature sensor. The real important part of the MAF is a hidden wire that actually does the air flow sensing.

It is a hot wire that is cooled by airflow through the tube, if the wire gets dirty, it changes the response and causes incorrect readings. It is also extremely fragile, so it is hidden up inside the sensor and air is drawn over it via the bernoulli effect. It should only be cleaned with a spray, never mechanically...

https://www.youtube.com/watch?v=Z3QuuEPef4k

-Charlie

 

[octanejunkie]

Check out link: (scroll down a little, and there are six pics that are literally a the steps you need to take... including putting a Phillips bit in vice grips if you don't have a ratcheting driver. Also, you don't need pliers to remove the connector.)

Toyota Maintenance: Tacoma and 4Runner 30K Mile Service

That's a pretty useful link for newbs :hatsoff:

 

[tvpierce]

Follow-up on this:

I've now gone through a few tanks of fuel.

First tank, normal commute of 10 miles each way. Net: 16mpg (no change)

2nd tank, I took a trip that was about 2 hours each way -- mostly 2 lane roads, 50-60 mph. Net: 20mpg! :thumb3:

3rd tank, back to commuting. Net: 19mpg :thumb3:

Wonder if on that first tank, the ECU had to re-learn? Don't know if the system is that sophisticated.

Anyway, great results from cleaning the MAF sensor.

 

[RedSled]

Follow-up on this:

I've now gone through a few tanks of fuel.

First tank, normal commute of 10 miles each way. Net: 16mpg (no change)

2nd tank, I took a trip that was about 2 hours each way -- mostly 2 lane roads, 50-60 mph. Net: 20mpg! :thumb3:

3rd tank, back to commuting. Net: 19mpg :thumb3:

Wonder if on that first tank, the ECU had to re-learn? Don't know if the system is that sophisticated.

Anyway, great results from cleaning the MAF sensor.

Thank you for the follow up.

 

[2001 Limited 285K]

[MENTION=159439]HMGT4R[/MENTION] I think we should consider doing this just for the sake of cleaning it...

I did this today for the hell of it. Hardest part of the actual job was getting out the bottom screw, which was stripped.

I used a Dremel with a right-angle attachment and a 1/8" left-hand bit (Drill Hog Niobium) to drill on the stripped screw and loosen it up. Once I got it loose it screwed out easily.

The MAF sensor was dirty but not as bad as I expected it to be based on all of the K&N air filter hate out there.

I hit the metal and the bulb with two or three rounds of the CRC MAF Sensor Cleaner spray to clean it then let it dry for a few minutes. Then I reattached the sensor with two Fullerkreg 0.7mm Pitch M4 x 10MM Socket Head Cap Screws from Amazon.

Actual work took only about 20 minutes but it took a few days to round up all the parts and tools. The Right Angle attachment for the Dremel was the hardest to get a hold of.

This is probably the easiest under-the-hood 4Runner mod there is. A good one for beginners to start with, in other words. Now I'm moving on to the hard stuff, like the notorious 4-inch "Deck Plate" and figuring out why I've got a weird engine vibration going on. Mounts?

 

[Endlessblockades]

I did this today for the hell of it. Hardest part of the actual job was getting out the bottom screw, which was stripped.

I used a Dremel with a right-angle attachment and a 1/8" left-hand bit (Drill Hog Niobium) to drill on the stripped screw and loosen it up. Once I got it loose it screwed out easily.

The MAF sensor was dirty but not as bad as I expected it to be based on all of the K&N air filter hate out there.

I hit the metal and the bulb with two or three rounds of the CRC MAF Sensor Cleaner spray to clean it then let it dry for a few minutes. Then I reattached the sensor with two Fullerkreg 0.7mm Pitch M4 x 10MM Socket Head Cap Screws from Amazon.

Actual work took only about 20 minutes but it took a few days to round up all the parts and tools. The Right Angle attachment for the Dremel was the hardest to get a hold of.

This is probably the easiest under-the-hood 4Runner mod there is. A good one for beginners to start with, in other words. Now I'm moving on to the hard stuff, like the notorious 4-inch "Deck Plate" and figuring out why I've got a weird engine vibration going on. Mounts?

The video at the beginning of this thread is useless except for theory. I didn't bother to pull the MAF sensor out of the intake tube, but simply removed the short section of intake ait tube containing the sensor (2 JIS/Philips screws on the clamps). No problem. You can hit the bulb and wires with the pinpoint tube that comes with the CRC spray.