When I do a VE tune, I copy my high octane table in to my low octane table, then go to the hot PE table and make all cells 100. Then go to engine diagnostics and set MAF fail frequency to 0, then reset the fuel trims. Now drive for a good time while scanning. when done go to teh LTFT table and click the upper left corner of that window, that will high light the whole window. Right click and copy. Then go to the tuner and choose VE vs RPM vs MAP, click the upper left corner again, high light the whole table and paste special, choose ADD. That will adjust all the cells by the off amount. Then repeat. however, do not reset the fuel trims again. Only that first time.

I don't have the option to set the MAF fail frequency to 0. It just doesn't show up in my tuner. That whole tab is blank, and I have no idea why, so I figure unplugging it will do the same thing.

Otherwise, I followed the exact same steps and got that problem.

Unplugging it does the same thing. Odd that your VE tables just wont come in. I still think there'* a mechanical or sensor problem. You simply can't tune around that stuff.

What could it be? It works perfectly fine, 100%, when the MAF is plugged in, but the moment I unplug it, the IAC valve goes wide open, fuel trims show rich, and I'm essentially unable to tune anything. Its as if the PCM doesn't know what to do when the MAF is unplugged. I've had the car go into speed density mode on me before, when I was driving through the mountains in Utah and the MAF went out of range due to very thin air going through very very fast. That didn't cause this problem at all. I wonder if there'* any way to force the MAF to fail without actually unplugging it. That might allow me to tune the VE tables.

You did check under the engine diagnostics tab right? That'* not the same as the engine tab. That'* where the fail setting is. It'* odd your IAC is doing that. That'* a huge vacuum leak and why your having problems. But why it opens when you unplug the MAF is beyond me. Have you tried unplugging the IAC as well as the MAF?

Yep, I did check under the engine diagnostics tab. For some reason I have nothing there, its just blank. I've seen screenshots of what should be there though.

I have not yet tried to unplug the IAC as well as the MAF. I could give that a try and see what happens.