Cleaning the MAFS - I'll Be Damned!

[8thTon]

OK, I admit it - I read about cleaning the MAFS and snickered a bit. But then I read a little more and realized it made sense, so I tried it. I'm pretty surprised in the difference it made in throttle response. I swear the transmission is responding differently too - more willing to kick down and perhaps holding gears longer.

It makes sense too. The hot wire MAFS works by passing an equal current through two identical pieces of heating wire. One is located in the air flow and one is sheltered. When air flow passes over one, it is cooled and the resistance changes. By comparing the voltage across the two you can directly measure the air flow.

If the one that is supposed to be in the air flow gets coated with stuff, then it isn't cooled the same. It becomes like the one that isn't in the airflow, so there isn't much signal and the computer sees less airflow than is there. This will change the fuel mixture in open loop modes, and might also change the load calculation for shifting.

 

[RoofHopper]

As a note MAF or any other sensors should only be cleaned with electronic parts cleaner, and not throttle body/carb cleaner, or any other harsh abrasive

 

[8thTon]

Yup!

 

[8thTon]

I drove it to work today and the difference is quite noticeable. I think the biggest change is in shifting of the auto - it is more willing to downshift and runs to higher rpms on normal upshifts.

 

[RangerDanger2]

I drove it to work today and the difference is quite noticeable. I think the biggest change is in shifting of the auto - it is more willing to downshift and runs to higher rpms on normal upshifts.

I did the same thing by using CRC (CRS) MAF cleaner. The difference in my '04 - 4.0 was nothing short of amazing. Before cleaning, I was getting 13.5 mpg on the highway. I'm now getting 14.5 mpg in town driving.

 

[8thTon]

And I got over 18 on my last tank, up from under 15 when I got it - though the MAFS is not the only contributer.

 

[sgtsandman]

I think it's about time to hit mine with some cleaner again. The mpg average is down a bit. I might be that the winter fuel blend is still in circulation but it has been a few years.

 

[Dirtman]

Winter vs summer fuel doesn't change mpg. Winter vs summer does. You could run winter fuel in summer or summer fuel in winter. No difference except how it evaporates. You will always get less mpg in winter no matter what fuel. Cold dense air needs more fuel to maintain 14.7:1 ratio. Technically your engine is running more efficient in winter, but warm ups, idle with heat on, driving the same way negates all that.

 

[8thTon]

Winter vs summer fuel doesn't change mpg. Winter vs summer does. You could run winter fuel in summer or summer fuel in winter. No difference except how it evaporates. You will always get less mpg in winter no matter what fuel. Cold dense air needs more fuel to maintain 14.7:1 ratio. Technically your engine is running more efficient in winter, but warm ups, idle with heat on, driving the same way negates all that.

Winter blend fuel contains more butane increase vapor pressure, allowing for easier starting (mostly on carbed engines). It reduces mileage pretty significantly, I usually lose a couple mpg as soon as it's out, regardless of the temps. I watch my mileage and can always tell right away.

This is about the time they switch back over so I'm hoping the step to 18mpg isn't due to that, but it's possible.

 

[Ranger850]

I had no idea they had a summer/winter blend. ?

 

[Dirtman]

They may not where you live. Its more of a cold climate thing like in the northeast. I doubt it gets cold enoigh in florida for them to be able to use winter mix fuel

 

[8thTon]

I'm still surprised by the difference in driveabiity, and mostly how much differently the transmission shifts. It changes the whole driving experience, and while I had been a bit disappointed that I didn't hold out for a manual, now the auto is what I had hoped it would be. It will run the engine up in rpm if I get on it harder and downshift much more willingly. The shift algorithm must be using the air flow as part of the load calculation - this makes sense because it does not appear to have a manifold pressure sensor so they must be calculating load from the throttle position, rpm and air flow.