Car was running fine, parked for a week or so and now dies immediately after start (doesn't stop like it's low on fuel, stops like if I were to turn the ignition to off). No amount of throttle changes this behavior. I did some Internet research and found that disconnecting the MAF sensor might lead me to the cause if it runs after disconnect. Exact same behavior when disconnected. While in the engine bay I found that if I disconnected the Boost Pressure Solenoid, it started up and ran (idle was a little high, but seems to run okay). The fact it's running when that solenoid is disconnected leads me to believe it's not (at least entirely) a fuel delivery issue.
Would you expect that the solenoid itself is the issue, or does that lead you to expect it's some other issue.
Some background history that MIGHT be helpful.
Radiator cracked sometime last year (saw low coolant light and stopped before engine got hot), finally got it replaced in Jan or Feb. Took for a test drive and was running fine, then stalled on us right as we left the neighborhood. (Threw a fuel delivery code, but only once, and I didn't take a pic. Didn't show in history or active codes)
Would not start. If it did start, would die shortly after (felt and seemed like fuel delivery issues, with a sputter stop). Let it sit a few minutes, and then was able to drive it home without issue. Have since driven it far and at freeway speeds without issues.
Car shows 2 engine codes, will provide images in comments.
P0140
P0141
Stored codes
P0036
P0140
P0141
None of these are NEW codes, it was running "fine" with them.
I haven't looked at a diagram for that car, so my thoughts will be generic.
Let's start with the codes. I'll run a non-boosted engine with O2 codes, because the worst it'll do is maybe run a little rich. With a turbo car, you're playing with fire (depending on the system design). It should default to limp mode, but extra fuel in a turbo engine can be a bad thing as detonation is even more likely (though lean is far worse).
Without perusing the diagrams for that engine, pI suspect disconnecting that solenoid somehow forces the computer to use a default mix setting.
Do we know if that solenoid is really a solenoid, or actually a sensor (manufacturers sometimes use those terms interchangeably). Or does the computer sense the current demand or position of that solenoid?
Here's the part from O'Reilly's
https://www.oreillyauto.com/detail/c/dorman-oe-solutions/dorman-oe-solutions-turbocharger-boost-solenoid/doe0/667107/v/a/18039/automotive-car-2004-volvo-v70?q=boost+pressure+solenoid&pos=0
Interesting, a vacuum solenoid.
I'd guess it's defective if removing it resolves issues. When you remove it, do you cap the lines?
Places like autozone should have a vacuum pump to test it. It's probably a simple switch that closes or opens with vacuum.
By disconnect, all I did was unplug the electric, left the component in place.
Also, looked under my car and I can see (and barely reach) some severed wires that run along the exhaust right around 1/3 back from the front of the car. I'm reasonably certain that's supposed to go to my 02 sensor, which would explain the code.
Doh! Sure would.
Shouldn't be too hard to replace, make sure to find a really good insulator replacement (just in case) and wire tie them to the body away from the exhaust.