John Griggs’s Ford Ranger:
“Edge”

General Index
[1 - Overview] [2 - My wreck!] [7 - Crazy Robin!] [9 - Candy's Ranger] [10 - Keypad entry system]

Meets and Outings
[11 - Centralia adventure Part I] [21 - Centralia adventure Part II]

How-To Articles
[3 - Overhead Console Install] [4 - Overhead Console Wiring] [5 - MAF mod] [6 - LED switch mod] [8 - Homebrew Remote Bass Control] [12 - Headlight/4x4 Switch LED Mod] [13 - General LED tutorial] [14 - EATC install how-to (pages 14-19)] [20 - IAT Resistor Mod (older engines only)] [22 - Automatic Power Windows] [23 - Cruise Control Pod LED's]

Modifying the Newer Plastic MAF

Introduction: (Must Read and 4.0 owners note warning!)

This modification is for the Newer Plastic Stock MAF's (2001 through 2003 at least). This involves changing a key element of your air/fuel ratio control system. If you don't understand it, what it means, and what the risks are, then don't do it! I will provide a link to some supplemental reading on MAF (Mass Air Flow meter) modification, explaining the pros and cons of this technique. I don't recommend that you glance at this page, figure you've got it down, and run out and cut your MAF. Take a little bit of time, think about it, and plan if you're uncomfortable with the risk.

What this modification does is remove some obstruction from the air intake system. Our Fords use a MAF which is basically a round tube with a sensor element inserted into it. The sensor element diverts a small sample of the air through it's innards, and generates a voltage proportional to the flow. The MAF sensor doesn't measure ALL the air, it measures SOME of the air, and the PCM assumes the sample accurately represents the total airflow. The photo to the right shows the full bore of a 4.0 liter MAF. Although the sensor has already been cut, it used to extend down to the red line in the photo. If you look at the two photos beneath step 1 of the instructions below, they show the MAF sensor element alone, before it was modified. As you can see, the size of the sensor blocks a significant portion of the bore. On 3.0 MAF's, because they are smaller, the blockage is even more dramatic. There is virtually no discernible physical difference between the 3.0 and 4.0 MAF sensors and they may in fact be the same. However, in application they are different enough to make the mod iffy on 4.0 engines.

So then, what we do with this mod is shorten and (redesign) the sensor tube so we can flow air with less restriction -- this CAN allow more air to flow into the engine. Why is it CAN instead of DOES? Because whether or not it WILL depends on whether your airbox, filter, exhaust system, etc. will all cooperate to allow greater (breathing). This mod may do almost nothing if you haven't done other modifications as well. The mod will convert the MAF from an impulse damped internal bypass design to a simple flow-through sample tube design, removing significant obstruction in the process.

Okay, then what might you expect to get from this mod? More top end power. This mod will do nothing for your low end torque, and part throttle power will not be noticeably affected. This mod it to give you more air at wide open throttle and high RPM when your engine is trying to take in the most air. But this can make quite a difference over 3000 RPM with the throttle wide open.

Why am I WARNING you to read this? Because things can go wrong. You can damage the sensor if you're not careful, and you can end up with a check engine light (CEL) or an unacceptably running engine. So many variables and tolerances enter in to a modern engine control system that it's possible the changes this mod introduces in your air/fuel ratio control may be outside acceptable tolerances and upset your PCM in some way. If you are concerned that this might happen, then get a junkyard or new MAF sensor and modify it so you have a fall back position. Read this article on MAF operation and modification to get some background and an explanation of the (dark) side of MAF changes. This is a great article, but somewhat discouraging. Be of stout heart! It can be done -- usually.

Literally dozens and dozens of 3.0 users have used my instructions to do this mod and no one has had any difficulties yet. The chief disadvantage is that the Idle may become a little rougher. This is because that tube design is supposed to reduce how much the MAF picks up the little puffs of air that result from the way the cylinders pull their air at lower RPM.

4.0 Owners PLEASE READ! The 4.0 has seen a fairly common problem with this mod. I'd estimate that one out of every three we've done has had such a rough idle that it was a problem -- sometimes even leading to chronic stalling problems. Although some performance gain was realized, it was not as great as with the 3.0. I DO NOT RECOMMEND THIS MOD FOR 4.0 SOHC ENGINES. If you do it, you really should have a spare MAF sensor to fall back on.

Hopefully you understand what we're trying to accomplish, and what the risks are. If you're ready to proceed, read on!

Time Required:

* Not much! You can do this in well under an hour. Take your time though, and do it carefully and well.

Materials Required:

* 1 security torx bit, size T-20, and suitable driver handle.

* Hack saw or other suitable cutter for thick plastic. I don't recommend power tools because the plastic is EASY to cut, and the sensor elements are delicate. It's at your discretion though, it's your MAF.

* Fine grit sandpaper or a fine file. You don't need much, just enough to smooth the cut edges.

Instructions:

Warning: Avoid all contact with the small sensor elements inside the MAF. Don't touch them with your hands, or tools. If cutting debris falls on them, blow or shake it off carefully, or use a clean soft brush.

To reset or not to reset: I did this mod WITHOUT resetting my PCM (disconnecting the battery for 5 minutes or more). I did this because I didn't want the automatic transmission to lose it's learned behavior, and I wanted to know if the mod moved the MAF so far off calibration from where it was before that the PCM could not tolerate it. Some think it's a better idea to reset the PCM before starting up after the mod. Among those of us who have done it, it's been done both ways and it works both ways. If you are going to reset your PCM, take off the battery cable first, before you start the mod, so the PCM can definitely reset and you won't have to wait when you put it back together (although, you should let it idle for 15 minutes if you reset it).

1. Remove your MAF sensor. You DO NOT need to remove the entire MAF. Photo 1 (right) shows the MAF sensor in place on top of the housing. You can see the two torx screws, and the T-20 bit that is used to remove them. The connector to the MAF is at the top of the picture. Push in on the latch in the top center of the connector, and pull it off. Then remove the two screws and pull the sensor out of the housing by pulling it straight up. It is entirely self contained and nothing is loose or will fall off so don't worry. Don't lose the screws though. When you get it out, it looks from the front like Photo 2 (below left) and from the back like Photo 3 (below right).

2. Make the first cut. Looking into the airbox (front) side of the sensor, into the hole near the top, you can see the floor of the arched hole that leads to the sensor elements. Cut just below the floor as you want it intact. Cut carefully and as straight as you can. The photo to the left below shows a rough cut 3.0 sensor after the first cut. The photo to the right below shows a nicely cut 4.0 sensor (although this is after both cuts).

3. The second cut is a little more delicate. You now need to remove the back of the sensor tube, so that air can flow straight through past the sensors. On the back (engine side) of the MAF sensor will be a slightly protruding area that is arched at the top like the arched hole in the front (airbox) side. You need to cut now from the bottom of the protruding part, towards the top of the arch so the back piece falls off. When you are done, a fingernail sized piece of plastic will have been removed (depending of course on the size of your fingernail). The image to the right shows a rough cut sensor from a 3.0.

4. Smooth the cuts with the fine sandpaper, being very careful not to damage or come into contact with the sensor elements. Clean any debris off the sensor carefully when completed.

5. Reassemble the sensor into the housing.Inside a 4.0, it will look like the photo to the right -- but you won't see this unless you have removed the MAF housing (unnecessary). Inside a 3.0 the housing is smaller and the sensor sticks down further. Don't forget to plug the connector back in!

6. Start the truck and let it idle for a bit, particularly if it's cold. If it is cold, let it warm up. If you reset the PCM, it's a good idea to let the truck idle for 15 minutes. This is the time Ford says it takes to (learn) to idle properly. The fast adaptation of the idle strategy occurs only after PCM reset. After that it's much slower. So, if you let it idle, it will learn to do it the best it CAN learn. Observe the idle afterwards. Our trucks never have a really smooth idle, but several (me included) report more kick periodically in the idle. Large changes in idle speed should not be present. Rev it a little after it warms up, or after the adaptation if you reset. If you get a CEL light anytime then STOP. It's time to consider your back up plan if you have one -- that is, put an unmodified MAF back in the modified one's place. If everything is okay, then take it for a drive.

Results:

You should notice an definite increase in power at higher RPM's. Power between 4000 RPM and red line in particular should be better. Have fun!

The numbers: -- for those who are interested

Here's what kind of increase in cross section you will get from a 3.0 and 4.0. This does NOT mean you will get that much more air flow. It just illustrates how much (resistance) you've removed by the modification.

OHV 3.0L V6: (Based on a 50mm MAF)

* 1.1 inch x 0.675 inches = .74 sq. inches (plastic area removed with cut).

* A 50mm MAF is 50/25.4 = 1.97 inch diameter MAF.

* The area of the MAF is 3.14 x 0.985 x 0.985 inches = 3.05 sq. inches.

* The old post was 1.97 inches x 0.675 inches = 1.33 sq. inches (blockage).

* Effective area of the MAF before modding was 3.05 - 1.33 = 1.72 sq. inches.

* Total effective area with mod is 1.72 + 0.74 = 2.46 sq. inches.

* Total percent increase is 2.46 / 1.72 = 1.43 (43% increase).

SOHC 4.0L V6: (Based on a 70mm MAF)

* 1.1 inch x 0.675 inches = .74 sq. inches (plastic area removed with cut).

* A 70mm MAF is 70/25.4 = 2.76 inches diameter MAF.

* The area of the MAF is 3.14 x 1.38 inches x 1.38 inches = 5.98 sq. inches.

* The old post was 1.97 inches x 0.675 inches = 1.33 sq. inches (blockage).

* Effective area of the MAF before modding was 5.98 - 1.33 = 4.65 sq. inches.

* Total effective area with mod is 4.65 + 0.74 = 5.39 sq. inches.

* Total percent increase is 5.39 / 4.65 = 1.16 (16% increase).

Acknowledgments:

I want to thank the MANY folks who did this mod to older style MAF's, and those who have posted articles on this mod, allowing me to easily do the research I needed to figure out if I was even going to try it.

Photo 2 through Photo 5 inclusive courtesy of Randy Salge (aka: riceburner, member of Generation-Edge.com).

Throttle shaft half-shafting

The throttle plate sits in a slit in the shaft which controls the throttle position. By removing half the shaft (leaving it with a "half circle" cross section) you gain about 10% increase in cross sectional area in the throttle body -- not huge but everything helps. After modifying the airbox, using a high flow filter, and doing the MAF mod, the next major restriction to "breathing" is the throttle body.

I didn't take any pictures of this as I did it very quickly with my Dremel one afternoon -- it took less than 1/2 hour including dismounting/remounting the TB.

Go to the Rogue Performance site listed in my links at the top of the page for further information, or just click here.