I am getting a trouble code saying my maf sensor is bad. Before I blow $150 on a new one, I would like to know if anyone has run into this problem. My car will run fine sometimes, and at other times it will have a rough idle or run rough at speeds below 50 mph. If I open it up, it clears up for a minute. Any ideas?
The PCM is really good about giving off odb-ii DTC error codes related to MAF sensor so yes it sounds like you have a bad MAF sensor. You can post the code for verification. It will either be performance related or low/high voltage. One thing you can try is removing it and cleaning the hot wire elements with electrical contact cleaner. Especially since it does get contaminated over a period of time or when using an aftermarket CAI/FWI with K&N style oiled filter.
It is important to get it resolved as soon as possible because it causes the PCM to command lean trim mode affecting fuel injector pulse width and causes misfiring which may ultimately damage your CAT convertor.
Your symptoms are consistent with a defective MAF sensor.
Yeah, like Bnaylor said, heh-heh. Seriously though, he is correct and you should address the problem ASAP to avoid other potential problems. If you have a reusable air filter element (like a K&N or Fram Air-Hog), the oil gets in the heating elements and mucks them up.
I do have a K&N filter, but I have had it since 2000 miles (I am at 60000 now). I have heard this might cause a problem, but after I replaced the MAF sensor for the first time the problem reoccured a few days later. After replacing it the second time it happened right away. I doubt that the oil is the reason for that.
I am pulling my hair out, and actually bringing it to the dealer (who sounded baffled on the phone too). I will let you know what I find out in a few weeks...sigh.
A trick a mechanic friend of mine showed me on the MAF.
Take it someplace where they can scan the real-time output of the MAF (not just the DTC code) and you'll probably find that it's reading zero.
Now, while continuing to monitor the output, rap it with a rubber mallet. With all 3 of my new defective sensors (and the original that failed), the reading would jump up to over 4000, and stay there for a short while.