I hava a NOS dry kit set up on my car, and it has been working like a dream, up until about 3 days ago. I usually turn the valve on the bottle off everytime I get out of the car for any length of time, but sometimes if I am going to making a five minute stop, or even for an hour, I leave the bottle open. I turn off the heater, and the presure would stay in the line until I reopened the bottle. Now for the last couple of days, If I turned off the bottle, the pressure would drop very quickly. I also have noticed that if I start the car within 15-20 minutes it backfires in the manifold when I first turn the key. I think it seems like the solenoids are leaking nitrous into the intake. Has anyone had this problem before? By the way, there are two solenoids that the nitrous has to go through to get to the nozzle. Could they both be bad, could a bad relay cause a small amount of voltage to keep the solenoids from closing all the way? I just put in new switches last month, and I'm pretty sure they are ok, because this just started. I also have a WOT switch that has to be activated to supply the ground for the relay to work. I have a relay that controls my switching, so the high voltage is all under the hood, and I'm using 125 Milliamp trigger through the switches to control everything. I'm just not sure if these solenoids have ever failed for anyone on the .Org before. Thanks for any responses.

 

I believe your diagnosis is correct. Doubtful they both are bad but possible.

Also doubtful the relay is causing it/them to stay open but to test just disconnect one of the wires to the solenoids and try opening and closing the bottle again and watch the pressure. With no power at all going to the noids they can't stay open for any other reason than that they leak.

If this is the standard kit those solenoids are not really heavy duty and I have read about them leaking before. I also believe they make a rebuild kit which is not too difficult to install, thats what I would recommend once you eliminate all other leaks. Although it doesn't seem like a fitting or you wouldn't get the backfire.

Good Luck

 

If you still have your NOS manual that came with the kit, on the 2nd to last page, there are instructions on how to disassemble and inspect your nitrous solenoids. There is a plunger located in the stem of each soleniod that contains a rubber-like seal. If this seal is protruding out of the plunger or the seal doesn't appear to be flat with a small circular indentation in the center of the seal, then the seal is swollen and needs to be replaced. The manual states that if left out in fresh air for several days, the seal may go back to it's original shape.

As far as leakage goes, the soleniods are designed so that if over-pressurization occurs and the plunger seal swells, the valves will fail to flow nitrous and will not leak.....in theory.

Hope this helps

 

Yeah, I think I am going to have to rebuild them. I just realized that the other day, with the hot weather, I was almost to 1500 psi at the bottle pressure guage when I was turning the valve off after a long drive. I didn't even have the heater on! I think it will just be safer to take off the solenoids, and rebuild them since I bought the kit used. I am free tomorrow, and I'll have some time to troubleshoot. I need to build a new switch plate now that I have some black plexiglass. Hopefully, Tony Littel will be over tomorrow and I'll do his switch set up.

 

Well, I'm all fixed. I have the 80 shot in there now, and I ran 0-60 in 5.6 with a passenger, and 100 lbs of tools. I wanted to go to the track last night, but thunderstorms said "no."