Cranking issues on my 2005 sierra 5.3 v8

Hi Becky,

One of the things you can do to pin down a MAF problem is to simply unplug it. When you do that the engine computer will be able to tell and will use a set of predefined defaults to run the engine. Those defaults will let the engine run just fine; usually well enough that you may not be able to tell the difference. Of course, it can't do the fine tuning for performance and mileage that it can with a functioning MAF, but if it runs fine with the MAF disconnected and runs lousy with it connected, then you're looking at a problem with the MAF or its wiring.

The thing is, some vehicles are really picky about the MAF and don't do well with aftermarket parts. So despite the fact that you've replaced it twice, it still may not be working right if it's not the one it wants. I'd suggest going online and looking at reviews to see if your rig needs a factory part (if that's not what you're using) or if aftermarket parts are okay to use.

If unplugging the MAF doesn't make any difference, then it's confusing as to why you're getting a MAF error code and I'm not sure what to tell you at this point. But if it does work fine with it unplugged, then you'll have to figure out what it is about the MAF that's giving you grief. We've already discussed the possible need for a specific make or model of MAF sensor, but if that doesn't pan out then you may have to start checking wiring and connectors. I know I had to replace the electrical connector to the MAF on my '99 Beetle when I was having MAF issues with it.

If you have or have access to a good quality OBD-II scanner, it's possible to view the MAF input information in real time while the car is running, which is another diagnostic technique you could use. I use the paid version of the Torque app on my phone, combined with a bluetooth OBD-II connector and that will let me view the airflow information in operation.

Hopefully those will give you some things to think about and hopefully give you a hand in figuring out what's going on with your Sierra. Try unplugging the MAF and let us know what happens.