For the buzz test (which in this case is more like a click test because the app I use only cycles the solenoid a couple times), I use Car Gauge Pro. Test is under diagnostics. Supposedly FORScan can do it as well, but I've yet to figure out how to find that option. Anyway, download that app and run the test, then get your head in there and listen to the #8. I don't know what order it goes in, but if you hear number 6 go off and then you hear #6 again, with no clicking on #8, then there's an issue. But, is it an injector issue or a wiring/FICM issue?
Stop the test and go get your multimeter. Set it to whatever setting is needed for 48+ volts. Unplug the connector going to that injector (there's a little silver clip you need to depress) and use the meter to check for voltage while the test is running, or while the computer does it's normal buzz test when you turn the key on. If you see 45+ volts during the normal buzz test, or if you see a flash of voltage (may or may not register a full 48 volts depending on how good your meter is....old analog meters work best for this), then the problem is the injector. If you do not see voltage, I would first ensure you have a good connection at the FICM
, and then re-check voltage. If still no voltage, you have a wiring issue and you'll have to start checking for grounds or open wires in that injection harness. Just be very careful with those pins in the connector. They bend VERY easily. Oh, and as for which pins to check, hold the connector with the silver clip at the 12-o'clock position. the two on the right are to open the valve, and the two on the left are to close. So check both sides.
There is an alternative to doing the above check, and you might have to do a little less work. Rather than check for voltage, unplug the #8 injector, remove the ground wire going to the far back intake manifold bolt (just remove a 10mm nut....though make sure to hold the intake bolt in place with another 10mm wrench, because that nut tends to bind and you wind up loosening the intake bolt by accident), remove the #6 injector connector, and plug the #8 connector to the #6 injector. Now run the buzz test again and listen for #6. If 6 worked before and now doesn't, you know it's a wiring problem for sure. If it does work this time, then your #8 injector is shot. Also, the reason I say you might get away with a little less work is because you're going to have to pull the air box all the way to the turbo, loosen and move the degas bottle, and then remove the nuts holding down the FICM
so you can move it enough to get to the #8 plug and pull/test it. If you have small enough hands, you can possibly leave the FICM
in place. Not a lot of room to work behind it, but it's possible. But, honestly, for the effort it takes to remove those 4 nuts, it's worth it to have the room to work.
Finally, I'm not familiar with the app you have, but FORScan is great for codes, and TorquePro is great for monitoring engine parameters, and is still fairly decent for codes as well.