I need some MAF advice.

[socaltoolguy]

I have a 2001 Duramax purchased new. I have been pulling a trailer of some kind since then. A few times after a hard pull the check engine light would come on but would go out after a few startups. I had it checked at the dealer and was always told that there were no stored codes. Well now it's long out of warranty. I took it in for service today and mentioned to the service salesman that it occasionlly would come on. Well, he dinged me $90 to hook up a scan tool and then he informed me that it had three codes stored in the ECM. They are P0101, P0236, and P0335. He said that it was a MAF problem and that the other codes were probably caused by the MAF throwing the first code. He said that they could fix it for only $555.60. I told him that the truck runs fine and gets great mileage considering I am pulling a 15k fifth wheel. The light always goes out after a few startups. I had also been told that it was probably a bad fuel cap but I had never got around to replacing it. I just make sure to screw it down extra tight. I told him that I would keep an eye on it. Anyway, my question is this, if it comes down to having to replace the MAF is that something that I can do myself? I have tools and some basic know how. I am not sure where or what the MAF looks like. If someone can give me a little help, I'm sure I can clean, check, reconnect or whatever is required to service this thing before spending a bunch of money on a new one. My truck only has 36k on it and it runs great. I would appreciate any help or advice that you more knowledgeable people might offer. Thanks,
Ray

[DmaxMaverick]

The MAF is a piece of cake to clean or replace, if necessary. Two screws and one connector, and none of it hidden (nice feature). It's the little black box (2"x2") on the top of the intake pipe, right next the airbox (toward the engine). The screws are tamper-resistant Torx, so you'll need that bit (you can get a full "security fastener kit" at Harbor Freight for less than $20, it contains about 100 odd fastener bits, very handy, and it includes the Torx bits). Otherwise, you can drill a hole in a regular Torx bit, and it'll work. I don't remember the size, but I can check if needed. Mine have been replaced with Phillips head screws (aftermarket intake), and the originals are buried in a box somewhere in my barn. The electrical connector is just a regular GM Weather-Pak connector. Clean and lube it with some dielectric grease while you have it apart.

The MAF can be cleaned with electrical contact cleaner, or rubbing alcohol. Make sure it's completely dry before reinstalling it. Don't touch the elements inside with anything but the cleaner. They are easily damaged. If you can see a piece of debris on the element (which would cause MAF errors), carefully dislodge it with a toothpick or other soft probe if air or a stream of cleaner doesn't do it.

The MAF can be had for less than $200 at www.gmpartsdirect.com. It takes less than 10 minutes to replace, even the first time. I doubt yours has failed, though. If it was bad, it would cause issues more than just during certain times. It could be contaminated, which limits its range. This will cause intermittent issues, especially during high air demand periods. A dirty air filter will do the same thing.

[socaltoolguy]

Thanks Dmax, that's what I wanted to know. I really don't think there is anything wrong with mine. My truck runs really great. I did forget in my OP that I have an Edge chip installed but I don't think that has anything to do with it. The check engine light came on a few times before I had the chip. I run the chip in the lowest mode because I haven't installed any extra gauges yet. I really baby my truck and only use it to pull our trailer while we are touring this great country. It is our only vehicle though. Thanks again,
Ray

[DmaxMaverick]

If you had the issue before the Edge, then it still needs to be addressed (clean, replace, or correct a wiring issue). The Edge is known for causing issues with the PCM in some cases. If you had previous a MAF issue, the Edge can/will exaggerate it. More fuel/boost is more air. More intake air is more sensing from the MAF. Try to duplicate it without the Edge installed, and correct it before reinstalling. If you can't duplicate it, the Edge may be pushing the range of your MAF outside what it can handle. Either way, you should still try the MAF cleaning, and clean/dress the connector. Chase the wires to/through the harness, and watch for chafing or poor connections (clean/dress them while you are there). No rocket science here. Disconnect, clean with some contact cleaner, squeeze in some dielectric grease, reconnect.