Solenoid problem

[atzi]

I have been running a NOS sniper 100 to 150 shot wet system for about a year on a 1979 Mustang at the local drag strip. Lately having some running problems at the top end but not out of the hole. So I deside to play around and test the flow of the nitrous and the added fuel by measuring them on a 10 second spray.
I sprayed the fuel into a jug then measured the cc's. Then I sprayed the nitrous off a bottle with only 2 lbs left. Calculated flow by weighing before and after the 10 second. Then installed a full bottle and sprayed. I ran into a strange problem. The nitrous soleniod would click but not spray any nitrous for a full second. If I hit the button on and off but not on for a full second i get no spray. Put the almost empty bottle back on (600psi) and soleniod sprays fine, no delay. Put the full bottle and the 1 second delay is back. Seems if pressure is over 800psi solenoid valve is sticking shut?


Anyone have a problem with the NOS brand solenoids????

[srsnow]

It sounds like the coil is bad. Check the ohm reading it should be between 1.2-1.4 it has changed a little over the years so it could be anywhere in that range if it is off of that reading then you would need a new coil. What is probably happening is that the coil can't open the solenoid under pressure but is able to lift the plunger just enough to crack the seal between the seat and the plunger's sealing surface and in doing so makes it easier for the plunger to come up the rest of the way. It is an odd problem that I haven't seen happen a lot. You also may want to check that the wires are all still in good shape if the coil is getting less than 12v it could cause the opening pressure of the solenoid to be lower than what was intended.

[atzi]

"It sounds like the coil is bad. Check the ohm ....... coil is getting less than 12v it could cause the opening pressure of the solenoid to be lower than what was intended."
Thanks I will measure that resistance and voltage. What do you think are the best quality solenoids and can a pulse solenoid be used on a system like mine that is just on or off?

[srsnow]

Most all newer solenoids I have dealt with can be pulsed, the only ones that really can't are the remote opener style of solenoids. I think any solenoid you get is going to comparable in quality. Some people will say that the smaller solenoids aren't as good which isn't necessarily true; the small solenoids are just limited in flow. Some nitrous solenoids started having issues with plungers swelling. This was caused by the vendor changing the material. As far as I know this has been fixed.

[atzi]

I checked the Voltage on both solenoids. KOEO (Key On Engine Off) voltage was 7.9 volts. But with the engine running KOER (alt. charging) voltage was 10.9 volts tested right at the solenoid positive and negative wires. Maybe there is no problem just lower battery voltage.
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Raced last night ran our best run the first 1/8th mile trip 7.38 seconds! Used the 125 hp jets. There was no solenoid sticking out of the hole. But the other 4 runs with nitrous we ran 7.90 to 8.40. :confused: Out of the hole we get an initial jump then vehicle sputters with nitrous. Pulled plugs they have a dry grey coating. I am thinking lean, if it was a nitrous low flow wouldn't I be getting a black soot on plugs same as a not nitrous engine running rich?
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[mrr23]

i'm wondering why you are only getting 10.9 volts to the solenoids. unless alternator is starting to give way.

[atzi]

Alternator charging fine, 14.3 volts. Have you tested the actual voltage pressure at the solenoids during full on, checking a few inches from the solenoid positive and negative?

[Steve-UK]

Are you running a relay to trigger the solenoid. If not you may be getting voltage drop across the switch activating the system.

[srsnow]

Are you using the ground wire for the solenoid for the ground when you test the voltage? If you are try using the negative side of the battery then re test the voltage if the voltage is good when you test it that way then it means you probably have a bad ground on the solenoid. If the voltage is still low than you probably have a bad connection somewhere on the power side. If so check where you are getting the power from (i.e. fuse block) if there is 12v there then start tracing your way back until you find where the voltage drop is.

[atzi]

Are you running a relay to trigger the solenoid. If not you may be getting voltage drop across the switch activating the system.

Here are the readings on the Nitrous Solenoid with a battery charger on low to simulate engine running and charging.

13.27 volts Fuse to ground
12.39 v out of main switch to ground
12.19 v going into steering wheel button switch to ground
11.2 v going out of button switch to ground
10.80 v at 4 way connector to ground
9.46 v at solenoid and ground
9.21 v at solenoid and solenoid ground wire
Total current draw at fuse 6.25 AMPS (2 soleniods and indicator light)
Resistance of nitrous soleniod 1.4 ohms
OK I added a relay to system. I also changed the Nitrous relay over to a PowerMax 3 way N2O solenoid from Harris. (will use the extra port to run a purge). Now the main and steering switch ingauge the relay contacts (relay mounted near solenoids on firewall).
Voltage now 11.3 volts!!!when battery voltage is 12.2volts(no charger on now) Went from 4 volt voltage drop to 1 volt drop.
Current draw is over 10 AMPs (Snapon Vantage(graphing meter)only goes to 10 amps) with larger solenoid.
you know the NOS instructions do not show or recommend a relay on this Sniper system. Maybe because it is their basic unit.

[srsnow]

The relays are only put in kits that usually end up in cars with computers. It sounds like a couple of the connections you had may have been the problem. You shouldn't need a relay, but because the relay requires very little voltage to operate even if the connections going to it are questionable they will still work a lot of the time. Glad to hear you got it working.

[Steve-UK]

The reason I mentioned relays is although the solenoid do not draw a lot of current with a relay it makes the the power circuit simple as it is battery - relay- solenoid- ground, only 6 connections, less chance for power drop. Also relays normally have better switching contacts, then the small micro swithes.

Glad you got it running :)