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better mass air senser


Active Member
August 19, 2001
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City, State
sparkle city, SC
Year, Model & Trim Level
93 XLT
The Hi-flow Mass Air Sensor will make a solid performance improvement - horsepower gains of 5% on normally aspirated 4.0s to a whopping 9% with a supercharger. This part should be on your hp wish list. Includes electronic module that has been specially calibrated to perform with stock air box*, K&N air filter and stock injectors for easy bolt-on horsepower. Very simple installation - no adjustments required. EO approval pending. Will not fit SOHC. For V6 and V8. Fits 91-94/96-00.

* Also available specially ordered with calibration for use with Hi-po Air Filter.

that was straight from explorer expresses's website....are the gains they claim true? And the KKM kit would just be the same as the hi-po K&N filter they sell, correct? Any info on this or any other mass air sensors would be apreciated!

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I don't know about most vehicles, but I can say without a doubt my 77mm Pro-Flow MAF made absolutely no difference to my 1/4 mile times on my '94 4.0L Ranger. My Ranger also had a K&N filter with 1/2 the air-box cut away, and an Exhaust-Tech cat-back exhaust. I made a few passes with my Pro-Flow MAF sensor then a few passes with my stock MAF sensor and my times were all within .1 seconds of each other. You couldn't tell when it was removed based on the times. Go to Pro-Flow's web-site and see what they say what horsepower a 55mm MAF is good to (which is smaller than the 4.0L). Here's a hint: 320 HP.

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That's a GREAT point. If that is true, then is there any reason for a larger throttle body?

Yes, the larger TB is about equal to the stock MAS size and besides size, the butterfly is usually better constructed.

my understanding is that a small maf will allow you to make tons of horsepower if you have a intake/mill/exhaust that really pulls the maximum amount of air through the maf. but on certain applications adding a larger maf will force a little more air into the engine and increase horsepower.

the max power a 55 mm maf will allow is like if you had a small straw in a drink with a lid and you turned it over and sucked on the straw. you could get a ton of the beverage through the straw right. but some mills don't really do that much sucking they just take whatever can pour through the straw, in that case a larger maf allows a little more air to come through and therefore can increase the power. i think that is the idea behind larger maf's

that all also goes for throttle bodies too right?

When I bought my MAF sensor from 4.0L Performance (Central Coast Mustang), they talked me out of the throttle body and talked me into getting the MAF sensor. They said the stock 4.0L throttle body was larger than the stock MAF sensor so if I changed the throttle body without changing the MAF sensor, I would never feel the difference. The funny thing was, I couldn't feel the difference with the larger MAF either :( A larger throttle body and a larger MAF sensor would likely benefit a highly modified engine. My experience on my 4.0L which was hardly modified showed no improvement. Of course if someone was willing to donate one to a worthy cause (me) I would be willing to try it on my SOHC. I will not buy another one until someone shows me actual experience in real world numbers of an improvement.

Going with a larger bore throttle body while keeping everything else stock will actually degrade performance, especially in the low rpm range. This is due to decreased incoming air velocity into the intake. A stock motor uses a certain volume of air, and using a larger bore throttle body will not change the volume of air that the motor uses, it will just slow it down.

Now if the motor has been modified to be able to use more air (internal mods and/or power adder), of course with more fuel also, then possibly a larger throttle body may be warranted.

There's always a balance when it comes to performance, and bigger is not always better.

I didn't mean a larger TB was necessarily good on a stock motor, just that it's usually better than a MAS. The BBK 66mm TB is a good match with an intake kit, catback exhaust, and a chip.

humble opinions sought:

So I have the KKM, and a bigger exhaust / Flowmaster 50 muffler. I also have the bigger TB, and have definitely noticed the loss in low rpm range power / torque. I AM getting a chip (Diablo chip). Should I get the MAF? In addition to that, I'm looking for a solution to the crappy intake Ford gives you which bottlenecks at the turn, and decreases the diameter by like +25%.
Will the bigger MAF help then?

For your intake tube, there are 2 options that I can think of that wouldn't be that hard or expensive:

1) go to your local muffler shop and see if they can make you a pipe, preferably mandrel bent. Also, auto stores frequently have exhaust sections that you could use to make an intake tube. They're almost always mandrel bent.

2) go to Home Depot and get some PVC piping that's the right size. Epoxy the joints to get a good seal, and make some flanges out of H.D. plastic.

For both options, you'll need some silicone tubing sleeves and hose clamps.

good luck!

Let me add some insight also. Mustangs don't even go with 77mm MAF until you plan on running 350+ horses. Normally you also put a 70mm TB to go with it. So putting a 77 on a V6 would definetely e overkill.

so looks like a "No"

What I'm hearing is:
There are cheap ways to get the bigger intake without the elbow. I'll explore those options.
Don't get the bigger MAF unless you plan on running more performance parts than a blower and headers (which I don't).


I still run the stock MAS and won't upgrade unless I upgrade injectors and have to match the MAS programming.

a year and half ago i did a TB and mass air swap on two rangers one a 2000 and one a 95 and both had exhaust. in both cases i used the pro-m 75mm and the bbk TB on both trucks there was a big increase in power. i recomend for all 4.0 to go with the 75mm and for all V8 mustangs or explorers to use the 77mm unit. if you want to do a good test you need to give the computer enuf time to correct for the changing of the mass airs other wise you wont get the correct numbers out of your mod so changing mass airs at the track is a bad idea for a performance comparsion.

Hey Guys.
I'm new to this thread as well as trying to squeeze a little bit more performance out of my 91 explorer. I must say all of you on this forum have some great tips and are helping me shape the mods I am going to do.

To get you guys acquainted with my project it is an almost stock 91 explorer 4 door 4x4 I have a mild exhaust on it and thats about it no headers. I was in the middle of changing the intake manifold gaskets as they were leaking coolant externally. While I had it all appart I started to look at the engine components and thought there must deffinately be a cheap way to squeeze some power out of this thing and some of my first ideas were flow flow flow. I have opted to fabricate a new plenum out of aluminum as it just seems restrictive I would then consider a new throttle body as that would be the bottleneck at that point I would then fabricate a new intake tube topped off with a K&N or equivilant. Where the intake meets the heads I was going to port the intake to match.

I assume some better injectors than stock would help?

As far as the exhaust goes I will most likely run headers.

Internaly the engine will remain the same, at least for now.

One of my problems is that I really don't know a ton about these engines I have built many carburated V 8's but that is an entirely different beast than this project

I was wondering if you guys could lay down a little input into my ideas and maybe where I could locate some of the neccesary and available parts IE: Larger throttle bodies, headers injectors and what is compatible.

Do they make high performance cams, pistons and related parts for the 4.0L

Once again thanks for all the tips and i look forward to any input you all would have.

now being 19 and not having much knowledge on engine parts i have read a few times about making larger holes inside the cold air box will improve your horse power and cost 0$ to do.. while what all of you are saying makes alot of theoretical sense to be honest i have no idea but will be doing the air box mod when i start working on my 99' sohc xlt. ohh and why not just go to ram air?? im not sure the cost differnce but if it isnt that much im sure youll get madd horespower compared to those costly non improving mods..

just food for thought

IMHO, the only way a larger MAF sensor or throttle body will have any perceptible effect on engine power is if the one you're currently using is restricting the airflow. Going to a larger one jus because of some claims or dyno charts is a waste of money IMHO. Unless the current one is a restriction point, what's a larger one going to do for the air flow? Nothing.