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What is the MAF sensor for? And is it that important?

11-05-2007, 10:18 AM
I recently put an air intake on my car. I first left the MAF sensor uninstalled, and just ran it with the air temp sensor, and it ran great. But then I thought to myself, I better but that MAF sensor in there to just to be sure my car gets everything it needs to run. But once I but it in there, the car felt like the horsepower was restricted. The acceleration was poor, and the responce was crappy. I then took it off, and the car ran as great as before.

Is it really that important to have that sensor installed, or can my car survive without it. Thanks for any info.

11-18-2007, 09:18 PM
I've always heard that it was highly important--to the point that if it crapped out, you were lucky if the car would even run. It may be great now, but as the air filter clogs up from use, you go up and down mountains, or there is another change in air intake volume for the RPM and loading of the engine, then your car may not be doing so hot. The mass airflow sensor would give the first clue that something has changed and your car would adjust quickly. I don't even see how it's even running, and emissions would likely stink (literally!). Definitely leave it connected.

11-19-2007, 10:38 AM
Thats what I thought to myslef too. But it runs great without it. But if I connect it, my car would shut itself down. But I've even tryed rotating the sensor 90 degrees so it wont cool down the littlle wires as much, but when I go faster or accelerate, when it shifts to the second gear, my car would stop, them go and stop and go, countinuosly until I deccelerate. Since my previous post I've tried many little things to see how I can have the MAF sensor connected without giving my any problems, but nothing yet that keeps my car running good. So I've left it out, and it runs perfectly. Without any running problems. I've read that its the sensor that regulates the air and fuel mixture, but I wonder when its disconected, how does the car know how much feul to give it? But I guess it knows, because its running and nicely too.

Here is a pic of what I did (I'll post it in the next one). Its a 92 Crown Vic.

11-19-2007, 12:25 PM
Here is the pic of my air intake. Note that I dont have the MAF sensor connected. It used to be in the trunk of my car but I have tried everyway to put the MAF sensor in there so I can make it work somehow. I've even tried turning it 90 degrees so it wont cool the little wires as fast, but this just made the car crazy. Until I find a better way to have the MAF sensor installed, I'm going to put it back in the trunk until I find a better way.


11-19-2007, 08:05 PM
I know the PCM (powertrain control module, the electronic brain) also gets clues on the fuel mixture from the oxygen sensors by the cat, and it may just calculate the amount it needs from the throttle position sensor. If the throttle position sensor's going bad, the car will do all sorts of cussing as there will be an error in the fuel/air mixture from time to time. It sounds like your mass airflow sensor may be fowled up. Are any of the wires inside broken?

12-04-2007, 10:54 AM
Reason it maybe running crappy is because the computer needs reset, since you've left the MAF off the computer as adjusted differently if you want it to run right if you haven't already install the MAF again and unhook the negative battery terminal for bout 10-15 minutes that's usually enough time for the computer to reset then you can hook the terminal back up and run it for awhile and let the computer get readjusted to the air intake its actually getting so it can mix the right combination of fuel.

12-04-2007, 09:49 PM
the MAF just measures the amount of incoming air. when it is dettached, or there is a fault code stored, the ECM uses input from the TPS and BP sensor to make an educated guess about how much air is entering the engine. it will (as you've noticed) run ok like that, but it is not optimum for performance and will increase fuel consumption.

have you tried using a shield inboard of your air filter? when the air filter is in the engine compartment like that it is very common to have fan wash create turbulance that detrimentally affects the MAF sensor readings. with the MAF hooked up how does it idle? rough?

with the MAF hooked up you should have the codes pulled and see whats what.

i didn't check your other thread but if you haven't cleaned the MAF sensor element with electrical contact cleaner or brake cleaner yet, you should. freshly oiled (or new) air filters will leave oil residue on the element that will mess things up.

12-05-2007, 01:52 AM
When the MAF sensor is taken out of the loop the PCM reverts to a richer mixture by default. With a cold air intake it's getting more air and with the richer mixture is probably why it runs so good.

12-05-2007, 08:51 AM
Hmm....never heard of using brake cleaner just that one special alcohol I can't think of and electrical contact cleaner.

12-05-2007, 10:39 AM
Hmm....never heard of using brake cleaner just that one special alcohol I can't think of and electrical contact cleaner.i've always heard that brake cleaner essentially was electrical contact cleaner, just in a larger can. honestly never verified that that was true, but it has always worked well for me on my mustang and on mustangs that i have worked on.

12-05-2007, 12:37 PM
well thanks for the tip, I've been thinking of cleaning mine just didn't know what to use without having to buy a can of something that I'll use once or twice.

12-05-2007, 05:48 PM
My MAF sensor is actualy clean. And it runs nicely when its idle. Its when accelerating like above 20mph when there is a problem. The car would actualy stal for a second and then accelerate a second then stal again and then accelarate and keeps doing this until I just stop. But this is no way of driving, so I took it off completely. I've read more into it, and I've read that the sensor works by cooling the little wires, the more air that flows trough them the cooler the wires become. But it seems that it cools it so fast that the PCM must think that there is a serious problem and cuts fuel to the engine and then the car slows down meaning less air coming in, but then starts to run again and cools the little coiled wired again with the massive air coming in and then it looks like a driving student whos barely learing how to drive is driving the car.

I maby thinking of making a little housing where the coils are, and only have one section of air hitting it, but not enough to cool the wires. But I dont know it this will work.

12-05-2007, 06:57 PM
Well not entirely sure if it cools wires but it is true that it lets the computer adjust fuel and air mixture. And can cause poor gas mileage

12-05-2007, 11:27 PM
sounds like you may have an intermittant wiring problem. may help to do these tests (might want to even jiggle the wires abit while you test them):

12-21-2012, 11:52 AM
Your car can run short term without a mass air flow sensor. It will run at the factory defaults; however your gas mileage will be back. I would recommend replacing it since your vehicle is running lean (not enough oxygen to the fuel ratio) considering your lack of acceleration. Do you have idling problems? If your car runs better WITHOUT the Maf sensor plugged in, than that's a sure way to know the MAF is bad.

mass air flow sensors (http://automammoth.com) from auto mammoth- I would check their blog out if you have any other maf sensor problems

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