MAF going bad?

**Lunatikgixxer** · 12-03-2011, 08:11 AM

I think maybe my MAF might be going bad? But im no expert.. Lately my car has been smelling like gas fumes pretty badly and i couldnt figure out what it is. So this morning i had the bright idea to unplug the MAF and the sensor that goes into the lid, then i went for a few test drives. The car doesnt smell nearly as bad as it did with it plugged in. So u plugged in the sensor for the lid and ran it a few more times.. Still doesnt smell too bad so maybe im thinking my MAF could be throwing off the PCM to dump fuel when there is no need to dump fuel? Any thoughts?
Also is it bad to drive you car around with the MAF unplugged?

**pajeff02** · 12-03-2011, 08:13 AM

Any codes?

**Lunatikgixxer** · 12-03-2011, 08:20 AM

No codes before unplugging and no codes after unplugging

**pajeff02** · 12-03-2011, 02:12 PM

When you unplug the MAF it sends the system into speed density mode. Airflow is calculated primarily using the MAP sensor. Once the engine is warmed up and goes into closed loop, feedback from the O2 sensors then results in the addition or subtration of fuel. Therefore, air entering the exhaust upstream of the sensors can result in a false lean reading and a call for more fuel. Can you see your fuel trims and O2 data stream with your scanner?

**Lunatikgixxer** · 12-03-2011, 04:12 PM

Originally Posted by pajeff02

When you unplug the MAF it sends the system into speed density mode. Airflow is calculated primarily using the MAP sensor. Once the engine is warmed up and goes into closed loop, feedback from the O2 sensors then results in the addition or subtration of fuel. Therefore, air entering the exhaust upstream of the sensors can result in a false lean reading and a call for more fuel. Can you see your fuel trims and O2 data stream with your scanner?

not with my scanner... It is very basic, my friend has a predator i will plug it in and see if it works but i doubt it..

**cammed goat** · 12-06-2011, 06:06 PM

Does the car hesitate when you are accelerating? I *think* that would be the first sign the MAF is going bye-bye. But, I could be wrong.

**JayTA98** · 12-06-2011, 06:25 PM

Luna have you cleaned the MAF?

**Lunatikgixxer** · 12-07-2011, 09:46 AM

i cleaned my maf about a month ago. I cleaned that sensor in the lid the other day with MAF cleaner... Didnt do much. My car still smells like gas and i dont know why.

**Lunatikgixxer** · 12-07-2011, 09:54 AM

Originally Posted by cammed goat

Does the car hesitate when you are accelerating? I *think* that would be the first sign the MAF is going bye-bye. But, I could be wrong.

It will hesitate only when i give it a good amount of gas when its cold. When it starts warming up it doesnt do that but i find that to be pretty normal...

**Firebirdjones** · 12-07-2011, 10:33 AM

Like Jeff mentioned, you'll probably need to scan it and see what's going on. You tried cleaning the MAF already, and unplugging it makes the problem better? Is it time for a new pair of 02 sensors?

I'm not much of an MAF fan anymore, I go SD tune on my stuff now and throw those MAF's in the trash

**Lunatikgixxer** · 12-07-2011, 11:42 AM

It seems like it makes it better anyways.... If i unplug my o2's and check them out is there anyway i could tell if theyre bad. Remember im getting no codes

**pajeff02** · 12-07-2011, 11:59 AM

You need a scanner that can watch their output. It should very rapidly cycle up and down if they are working properly. Again, you can also use a scanner to check your short and long term fuel trims as this can help to isolate the issue. If the trims are running around 0 to +/- 3 you are generally right in the ballpark.

**Lunatikgixxer** · 12-07-2011, 12:03 PM

ok i will try to check them out thanks

**Lunatikgixxer** · 12-07-2011, 07:16 PM

ok i got a scanner hooked up to it and at idle it reads normally around what you said, occasionally it will jump it to like +6 or something. When i am cruising or accelerating it will jump all around ive seen it go up to +30 on both bank sensors.. Heres the catch, I am using this Torque Pro app on my android phone and a bluetooth OBDII tool. Ive read this is a pretty accurate scanner but who knows how accurate. It reads my RPMs and MPH very accurate but im not sure if its reading the O2 fuel trims correct... You would think it is since its reading directing off the PCM but who knows.. If it is reading correct, are my O2s bad or going bad?

Also, something really weird happened, i was playing around with the MAF sensor when i was leaving work because when i started the car it smelled like gas really bad. So i shut the car off, unplugged the sensor, and let it warm all the way up, plugged the sensor back in and went home. On my way home i was playing around a little and i swear my car felt like it gained 50hp. I was like holy shit. What the hell would cause that? It felt like the car woke up finally.

**pajeff02** · 12-08-2011, 02:56 AM

Definitely calling for fuel enrichment. Is it a stock or aftermarket MAF?

**Lunatikgixxer** · 12-08-2011, 01:13 PM

Stock MAF. Im pretty sure its the original one

So youre saying its running LEAN instead of rich?

**pajeff02** · 12-08-2011, 02:46 PM

Rich. Something is telling the PCM to add fuel. Any leaks in the exhaust -- cracks in the welds, poor connectons, or a blown out gasket that would allow outside air to be drawn into the system?