Do you have the manual that came with the nitrous kit? If so, that should explain how to properly test the system. However...you could do it the way you said with the nitrous line removed from the throttle body. But then you'll have a big hole in your incoming air tube that would cause a big vacuum leak. Not sure if that would matter or not really? It could possibly affect the way the computer adjusts the timing & fuel...but don't quote me on that. A new Hobbs switch is cheap though. And you should be able to buy one from your local speed shop, or from the place that installed the system. Your 155lph pump should be sufficient for your 75 shot. Are you sure you have the 75hp shot nitrous jetting in there, and not possibly bigger jetting? Just a thought. But even with the 75hp shot you really should know if & when it is working. I mean...it's frickin nitrous! If your system is working properly...then you should definitely know when it kicks in. And you really shouldn't be using the nitrous under 2500rpms...3000 is even better. Your timing at 12 sounds fine. although it wouldn't hurt to put it at 10 just to be safe. You can always pull your plugs right after a nitrous run and try to get a feel for how the nitrous & fuel is burning in them there cylinders. I would seriously recommend changing your fuel filter. All it takes is one dirty tank of gas to clog that thing up. Even if the guy did change it just 7,000 miles ago...you should change it again. Just another thing to eliminate as the problem, you know.
As for the nitrous leaking out now, I'd seriously think about taking it somewhere else to have your system checked out. But being that you already paid this other shop I'm sure...you'll probably want to go back there first and demand that they get this thing running correctly. A nitrous system is fairly easy to install. I can't belive yours is leaking. I hope this mechanic knows that he should be using liquid teflon on all the nitrous connections and not teflon tape. That crap can clog your solenoids and then you'll have to get them rebuilt. Is this system new? If not, then maybe you do need to have your solenoids checked for dirt and gunk and get them rebuilt. It's not that expensive. Sorry this is so long. Try to answer my questions about the manual and whether or not this system is new. don't worry...we'll get this thing figured out.
