Car stall when MAF plugged in? '98 V70

[bmdubya1198]

Looked at the fuel trims yesterday at idle after a drive. They were anywhere from -2 to 8, usually hanging around the higher side (~0.8-3). Of course, because I was testing it, it wasn't really surging as much as it was. The idle may have dropped a little bit a couple times by maybe 100 RPM, but overall there was no surging.
I haven't tried running without the MAF sensor yet, but I might try that out tomorrow if the surge comes back today.

[abscate]

Under 3 at idle means you don't have a vaccuum leak of consequence , at least when you tested it

[bmdubya1198]

Well, that's a plus. I'm thinking the MAF sensor is probably on its way out.

It is worth mentioning, however, that my evap L hose was leaking. I have it wrapped up in electrical tape now, but it made P0455 go away, so I consider it fixed for right now. I'm going to replace both the L hose and J hose very soon.
I don't think that is affecting anything, though, because if it was leaking bad enough to cause the car to idle poorly, it should throw a code, since when it was throwing a code (but not a CEL, code was pending) it was running fine.

[abscate]

Purge valve is closed at idle so no extra air.

The Short term fuel trim is a wonderful diagnostic. I know your evap isn't leaking at idle because if it lets in any air not seen by the MAF, the ECU will add fuel to compensate and the STFT would read 10-20%

[bmdubya1198]

So the STFT is now reading around 12-16. It's only for a couple seconds at a time, but the trims were staying on the high side while I tested it.
Exactly as it happened the last time, I put the car in park and within about 2 seconds, the CEL popped on and P0455 appeared. That's what prompted me to check the fuel trim, which kept bouncing up higher than I liked.
One thing to mention, though, is before I left, I swapped my MBC back to the TCV. The car felt fine, although it had a little hiccup while stopped at an intersection. I thought it might just have to relearn fuel trims with the different boost levels, but I'm not sure how much the TCV would affect that.

[bmdubya1198]

So the STFT is now reading around 12-16. It's only for a couple seconds at a time, but the trims were staying on the high side while I tested it.
Exactly as it happened the last time, I put the car in park and within about 2 seconds, the CEL popped on and P0455 appeared. That's what prompted me to check the fuel trim, which kept bouncing up higher than I liked.
One thing to mention, though, is before I left, I swapped my MBC back to the TCV. The car felt fine, although it had a little hiccup while stopped at an intersection. I thought it might just have to relearn fuel trims with the different boost levels, but I'm not sure how much the TCV would affect that.

[abscate]

The EVAP system is only tested at idle, so the code appearing there is not correlated to the fault. A high STFT is indicative of a vacuum leak but search outside the EVAP system for that

[bmdubya1198]

I don't even know where to look at this point. I've replaced pretty much all of my vacuum hoses over the past year or so, and after checking pretty much all of them today, they're not leaking. Just a couple weeks ago I replaced the IAC outlet hose and the vacuum tree o-ring, so those are good. The throttle body inlet hose looks a little cracked, but it's definitely not leaking.
What else can I even check? This car is driving me nuts...

[abscate]

Did you smoke it yet??

[bmdubya1198]

I have not. But it is sitting in the garage right now with the intake torn apart. I've gone over all of the vacuum hoses I know of, and they are all solid. The connections are all good and tight, so if there is a leak in those hoses, it's a very small split somewhere along the hose.
As of now, I'm down to a possible leak at the CBV or the IACV is shot. And I still haven't ruled out the MAF, I might pick one up at the Pull a Part this weekend.