MAF (again) What does it do and affect

[thechevyhdman]

Can someone tell me the exact purpose of the MAF sensor and what works in unison with the MAF. Like the MAF measures air coming in correct?. If my MAF is bad like in my prior posts, does the info the MAF sense change timing, fuel delivery, etc. Basically what I am asking does the MAF have such an importance in engine electronic systems...that it can chage timing etc? I dont know if you understand where I am coming from on this thread. Obviously my truck doesnt like to run properly in the rain......only with the Juice on too. Im leaning towards the MAF sensor being the culprit....what I am trying to say is does the MAF sensor play such an important role in engine "controls" that it could tell another sensor or computer to change timing start knocking and start blowing huge amounts of white smoke......Before I go out and spend 150 bucks on a new MAF I want to be sure that this is what my problem is. I always thought that the MAF sensor adjusted fuel/air mixture/timing....If so then I bet thats my wet Juice issue if it purpose isnt as importat as that.....Im going to start looking for other Gremlins causing my problems, TIA Bill

[FightinTXag]

>start blowing huge amounts of white smoke

I always thought white smoke meant burning coolant, blue smoke (sometimes mistaken as white) meant burning oil, and black smoke meant a fuel delivery (or turbo) problem. I'm new to diesels though so maybe they're different.

[Geerrhead]

Bill,

The definition of the acronym "MAF" is Mass Air Flow. There are basically 2 kinds of Electronic fuel injection system's. MAF & Speed Density. Speed Density was common on Mustang's. It had no MAF, instead it used predetermined software to calculate air/fuel mixture's. The Mass Air Flow sensor tell's the computer the actual amount of air the engine is ingesting.In laymen's term's, the computer will want to to reach a target air/fuel ratio. If under full power, the ECM is under acceleration enrichment. It uses the MAF value to figure out how much fuel to add. If you add a free flowing air filter and exhaust, the MAf will show ahigher amount of air going into the engine.I'll try to explain how this sensor works, so you understand how water effect's it. If you look inside the MAF, you will see a thin wire, AKA "hot wire". Voltage is supplied by the ECM to the MAF. As air moves across the "hot wire", it cools it. The ECM try's to maintain a constant temp on the "Hot Wire." When more air moves thru the MAF, the ECM has to supply more electricity. There are tables in the ECM that translates the electricity into into Grams Per Second. Are you still with me? When a foriegn substance reaches the "hot wire" it skews the value's. For instance, when water hit's the "hot wire" it cools it more than air, fooling the computer. The computer thinks that you are ingesting an enormous amount of air, so it add's a lot of fuel! The result is smoke out the tailpipe and the motor bog's, from being overly rich. It would be similar to pulling a manual choke closed on hot engine, lot's of smoke and no power. I have seen this occur on Sevilles. They had a large air box that would hold a gallon of water. The car would drive fine, except under full throttle, when there was enough vacuum to suck the water into the MAF. If you have access to a Tech 2, you could monitor MAF,TPS, and O2. When the failure occurred, take a snapshot. YOu should see the MAF go straightline. I hope this helps. ;)

[Geerrhead]

FightinTXag,

You are correct with gas engines. Unburned diesel is also white smoke. Have you even seen a tired Diesel start in the winter? I can remember Cab Over Mercedes Smoking out the parking lot until they warmed up. Diesel's are compression ignition. So when they are tired and cold, a lot of the fuel is not burning, hence the white smoke. We all know when it burn's, and you are running rich, it's black as coal.

[TraceF]

If you can get a MAF sensor for $150 you may want to go ahead and trouble shoot. The last one I bought for my 2000 gasser was $290.

[thechevyhdman]

Im just guessing on it being a MAF sensor. I think dollars to donuts thats what it is. What is funny though. Truck will only screw up when the humidity out is high like rain is obviously 100 percent humidity. Today I went trashing through puddles all day up and down RT 7 in CT...no problem....I cannot see any visible signs of water being sucked down my intake tube...I mean I dont know if this makes sense at all.....Water spray (wet roads) doesnt seem to be the cause of this...but high humidity in relation with wet roads seems to be when TSHTF. Im also thinking maybe TPS sensor...or I dont even know if these trucks have any but maybe an 02 sensor?....Geerhead....shoot me an email when you have a chance..Gmanjr96@aol.com

[mackin]

Wonder if Edge intercepts Barometer sensor.....??

When the weather changes, i.e., raining, it is out of range or has running issues with 02's?? Just a guess......

Bill my stock box is ready, I'll bring it Friday,oily couch cushion in place.....

MAC :D :D :D

[TraceF]

thechevyhdman-

Gotta symphathize with you. I've been lucky I guess, so far no problems in any weather.

[Kennedy]

The MAF sensor measures a PORTION of the air and uses that to give the computer the amount of air flow in g/s. If the MAF sensor reads low, OR the path of flow is altered so it no longer flows the same at the sensor, off idle performance is the first to suffer. I modified an air box lid and the subsequent changes in air flow caused the truck to run almost like you took the turbo off! It was really mushy, and unresponsive. I corrected this modification, and it was good as new again.

I doubt the MAF sensor is truly bad if it is intermittent. SoMN can comment on how a failing sensor acts...

[thechevyhdman]

JK today I took a risk and sprayed my MAF sensor with water from a spray bottle. Didnt do a thing.....starting from scratch again :mad: Bill