I'll try and explan what the heck is going on. I've a supercharged Z28 with a 150 shot of n20. It ran fine with my harris speed work controller. Recenlty, I was driving my car and I turned on the activation switch for my n2o. I turned on the gas and had it set for 20% and up to 100% after 5 seconds. I hit the throttle and my Z started backfiring like crazy! I pulled out of it and it was fine. Later, I decided to run it with out the n2o, and just using the fuel soleniod to add more fuel to my current tune. So, I turned on my activation switch and as soon as it activated, it started to backfire. The perplexing thing is I used to run my car with a full 150 shot and it ran great. Now, it seems as if it's getting too much fuel? I have burned a new chip to take some fuel out and it has seemed to reduce the back fire quite a bit. But what changed???? it used to run like a raped ape and now too much fuel????

The only thing that has been done to the car was I lashed the valves 1/2 turn past zero lash. This is how I always have ran my valves. the reason I had to lash my valves was a nut went bad and started backing out and would not hold.

Any Ideas?

I'm thinking of first,

Checking plug gap, then fuel pressure and timming. After that, if it is still backfiring when I activate the system...with the n20 off of course I will put in a smaller fuel jet, maybe the 125 fuel and see what happens.

any other ideas?

 

have you verified that the nitrous solenoid is opening????

 

I get back fires with and with out the n20. For some reason, it's running really rich only when the n20 system is activated. With the bottle on and with the bottle off the car backfires really bad???

 

I understand it does it with the activation switch on....have you verified the nitrous solenoid is opening when the system is activated.....if it is not you are spraying fuel only and will cause your problem.

close the bottle and make sure the nitrous feed line is empty, remove the fuel line from the nozzle and place in a catch can.....activate the kit and see if both solenoids are clicking.

 

Dave,

Sorry about the confusion here. I have a supercharged car. I run my N2O with my hobbs switch when I hit 4psi. I run a total of 10lbs of boost. Here lies the problem. I go out, do a run and I activate my system. I keep the bottle closed because this allows my fuel soleniod to acitvate without the N20. When I am tuning my chip, I can see a difference in HP when I have the fuel soleniod activate and I am not using my N20. I disconnect my N20 soleniod's when I do this via wire/plug connectors. My car never backfired doing this before last week. Now, I take my car out and do a run with the fuel soleniod activated and it pop's like crazy? Runs fine without the N20 system activated. Then I do a run with the N20 soleniod activated thinking this may help since I'm running rich. NOPE! It pops with both soleniods activated and the bottle turned on too? I checked my soleniods and they both click. One thing I have always noticed is that my N20 soleniod clicks really loud, the fuel soleniod is much more difficult to hear, it's always been that way for some reason?

I'm thinking one of a few things;
check the ohms on my soleniods. what ohms should I be seeing with the system on and off?
Plugs...check plug gap
check all connections to my system including the Harris speed works controller

Thank you for your help

 

Thank you Ray @ NitroDaves for your help!

Check this out. I took my Z out for a test run and noticed the harris controller was not activating every time I activated my system??? I disconnected the progressive controller and took my car out for a test drive. I did verify that both soleniods worked when activated prior to my test run I activated my system without the Harris progressive controller and with the bottle OFF. My car ran like a raped ape! Then I thought, I think it may be fixed. SO....I turned on the bottle and tried to make a run. I got on it in first gear for about 2 seconds and it seemed to be working. Then I go on a freeway on ramp. The dang thing backfires when I have the bottle on??? I heard a snap/pop out of the exhaust so I quickly took my foot out of it!

So, taking off the progressive controller for some reason seemed to help my problem of backfiring when the bottle was off.

I still have backfiring issues with the N2O turned on???

What gives