I recenlty decided to put an N2O kit on my Z28. When I run the car with out the gas, it runs great all the way up to 6500rpm's. When I put the N2O on, The car backfires like a machine gun? I tried the 50 jets, 75, 100 with no changes. I put the 50 shot in with jets for the 100 shot and it still backfired???

What gives

Bottle pressure is 1050psi. I fought that issue and now on to anohter one

full bottle, the bottle was filled last year and not used till recently
tune is good
timing is 6 deg advanced
fuel psi is 52

 

It's popping out the exhaust, not pinging if that helps


I pulled the nozzle off and activated it, the fuel sprays..then drizzles after a bit. I'm thinking that's because the car is not running an sustaing the fuel pressure. The N20 sprays with an occasional studder?

 

Might want to add basic info like the year of the car, and the type of nitrous system. Without that, its hard to tell you what the problem is.

 

Sorry,

1992 Z28, 5.7L engine

Trick flow heads
SLP headers with 3 inch cat back
compucam 3032 cam
Accell 24lb injectors
Walbro 255lph fuel pump
MSD ignition
Nitrous Express kit up to 150hp..wet kit activated by a tps switch. I will soon upgrade the kit so it will only activate at a certain rpm.

That's about it. I've got 64K miles on her. I've no idea of why it popps out the exhaust, I was guessing it was running rich, so i put a larger fuel jet in the kit, and it made no difference. I put a leaner jet in the fuel side and it ran way worse. Popping out the exhaust like crazy:?: I pulled the plugs and they are brown with black on the outer ring. It's acting like it's running way rich, but it runs worse when I lean out the jets on the NX kit. The N2o has been in the bottle for about a year. . . Sitting in my garage.

Thank you

 

Sounds like you have a restricted fuel supply. Activating the fuel solenoid without the engine running is not a valid test, since the fuel pump only operates for a couple seconds and then shuts off if the engine isn't started.

Do you have a fuel pressure saftey switch? If you set the switch too close to the system fuel pressure, you may get some stuttering when the fuel solenoid opens and there is a brief pressure drop in the system.

Probably a good idea to put a fuel pressure gauge on the line to the solenoid, and watch the fuel pressure when you activate the system. But be careful... running it lean will cause detonation.

The fact that the N2O has been in the tank for a while doesn't make any difference. It doesn't "go bad".

 

if its poping there is un burned fuel igniting in the exhaust. Thats where the sound comes from.

 

Yea, I figured unburned fuel was my problem, but I wanted to rule out the possibilty of it runing lean. I have some 36lb injectors that I put in and tuned the chip. Car runs great without the Nos on. As soon as I activate the gas..Poppppppppp! I retarted the timing to 4 deg advanced, problem is still there!


I have no idea! HELP PLEASE

 

Good thing I had a spare ignition module lying around! My module was bad. The confusing thing was it would run fine up to 5000rpms then start backfiring. Swaped it out for the new one and shazam, it's running awesome!

thanks for your help everyone!