Mileage to replace MAF and O2 sensor?

anniesball72

anniesball72

Member
I have ~145000 on my 2002 4Runner that is supercharged, 2.2 pulley, URD 7th, w/ 5speed. I keep my foot out of it for the most part.

I live about 3000ft elevation and only get 12mpg city and up to 20mpg fwy.

My city mpg really dropped off in the last 20,000 miles.

The MAF and O2 sensor are both OE and I'm wondering when it's time to replace them?

In the hopes of better mileage.
 
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anniesball72 said:
I have ~145000 on my 2002 4Runner that is supercharged, 2.2 pulley, URD 7th, w/ 5speed. I keep my foot out of it for the most part.

I live about 3000ft elevation and only get 12mpg city and up to 20mpg fwy.

My city mpg really dropped off in the last 20,000 miles.

The MAF and O2 sensor are both OE and I'm wondering when it's time to replace them?

In the hopes of better mileage.
Click to expand...

Correction! replace A/F sensor
 
anniesball72 said:
I have ~145000 on my 2002 4Runner that is supercharged, 2.2 pulley, URD 7th, w/ 5speed. I keep my foot out of it for the most part.

I live about 3000ft elevation and only get 12mpg city and up to 20mpg fwy.

My city mpg really dropped off in the last 20,000 miles.

The MAF and O2 sensor are both OE and I'm wondering when it's time to replace them?

In the hopes of better mileage.
Click to expand...

Why replace the MAF? Is it damaged or just dirty? Get some CRC MAF cleaner and have a go at it.
 
I bought my 4runner with 111,000 miles on it. Replacing the Air/Fuel sensor and the Oxygen sensor was one of the first things I did on my rig. I wasn't throwing any codes at the time but I saw it was a recommended to change these so I did. My sensors could have been perfectly fine but I was thinking I might get better gas mileage by changing the A/F sensor and decided to do the oxygen sensor as well while I was underneath the rig.

For us California folks, the front sensor, closer to the engine, is an A/F sensor and the rear is an oxygen sensor. You may just want to start with replacing the A/F sensor, cleaning the MAF sensor, and cleaning the throttle body. I imagine you could wait until you're throwing a code to replace the rear oxygen sensor but it might be good just replace both of them like I did.

Here's a link to a good write-up on replacing the sensors:https://www.4x4wire.com/toyota/4Runner/tech/O2_Sensor/

Just do a Google search for cleaning the MAF and Throttle body. You should be able to find everything you need to do this job properly because it's been covered very well on multiple forums. The MAF can get dirty pretty quick if you're driving a lot on dusty dirt roads. I wouldn't replace the MAF sensor unless you're getting codes that you can't clear from cleaning it.

Good luck!
 
Before all that replace things that will have just as large an impact, plugs and plug wires, clean the throttle body out, maybe run some fuel injector cleaner in your fuel tank, clean things up. I'd rather do that 1st than replace the 02 sensor and MAF.
 
I'm at 230K+ miles and I've got 33s lift, etc.

4WD Auto.

I just got 17 MPG solid on a long 300 mile plus road trip, kept the speed below 70 the whole time.

Original MAF. Original CATs.

O2 sensors, plugs, wires, fuel filter etc all relatively new.

I don't have any plans to replace the MAF at this time. I usually clean it with the proper spray about once every 2 years.
 
BrianSD_42 said:
I'm at 230K+ miles and I've got 33s lift, etc.
Original MAF. Original CATs.

O2 sensors, plugs, wires, fuel filter etc all relatively new.

I don't have any plans to replace the MAF at this time. I usually clean it with the proper spray about once every 2 years.
Click to expand...

This is the right idea. Check fuel mileage over a month for an accurate average based on driving habits, etc. Replace ignition parts, filters, et al if needed. MAF condition will reveal itself. No need to guess at it.
 
BrianSD_42 said:
I'm at 230K+ miles and I've got 33s lift, etc.

4WD Auto.

I just got 17 MPG solid on a long 300 mile plus road trip, kept the speed below 70 the whole time.

Original MAF. Original CATs.

O2 sensors, plugs, wires, fuel filter etc all relatively new.

I don't have any plans to replace the MAF at this time. I usually clean it with the proper spray about once every 2 years.
Click to expand...

This is pretty much exactly me, everything relatively new (last 10k miles) except for the cats and MAF, lift, extra weight, all that good stuff also... Cruising 70-80 last weekend I got right around 17, 16.9 to be exact. I know when I keep it closer to 60-65 she'll get close to 20 though. Speed makes a huge difference, but when the limit is 70 and everyone is already running 15-20 over running 10 under is dangerous in my eyes. I stay around the speed limit or with the flow of traffic if needed.

In the city I get like 14.7 on average though. Driving to work in the cold, driving home from work in stop and go rush hour. Driving around town in stop and go, etc.
 
I agree with everything being said. I bought my 2000 in december and on the drive home on the highway cruising 70...i got 14.5!!!!!! over the next month i changed plugs, wires, fuel filter, front oxygen sensor, cleaned MAF (make sure you spray the wire, mine was throwing a code and I blindly sprayed the MAF not knowing about the wire, I then looked in and saw the wire was gunked with dust/dirt. no more code) cleaned my TB, and ran seafoam. I took a 2 hour (90-95%) highway cruising 70 and got about 19.5. around the city in ohio, I'm lucky to see 15.5 at best.

Best of luck.
 
!!!

Yoter said:
Holly shit you have a 5 Speed with Multi Mode! Thats awesome!
Click to expand...

Yeah 5 speed with Multi mode!!!! I just had it done about a month ago. It's sooooooo much better on hills. With the supercharger I can hold almost any hill in 5th. It temporarily has a grey Hilux shift knob on it till I get a black FJ style shift knob.

Thanks to all who replied to this thread. I am going to get a new Denso A/F sensor.

 
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