1992 KA24DE Rough Idle problem

[240sxracer20]

I have a 1992 Nissan 240sx wthat has been giving me fits. It started out with a misfire on the #3 Cylinder. It turned out to be a bad injector circuit in the computer so I replaced it with a different computer. Then, I began having problems with the idle. The car eventually began flooding itself out. I have replaced the fuel injectors, fuel pressure regulator, fuel rail, coolant temp. sensors, distributor cap, plugs, and checked the timing. Now, the car starts fine when cold and runs good at RPM except for an intermittent exhaust backfire(minor), however, after the engine warms up it slowly loses its idle and lopes between 300-1000 RPM. If you give it gas, it will stumble for a split second but once you get above 1200 RPM it seems to be OK except for the intermittent backfire. When you let off the accelerator it wants to die when its trying to find its idle. The plugs now have gone from being full of gas to having carbon on them when you pull them out. I don't know what else to try and would appreciate any help you might be able to offer. I have not replaced the O2 sensor and am hesitant to spend any more money without some direction. The car is actually raced on a dirt track so the exhaust system has been removed in front of the Catalytic converter. Anyone with any ideas?

[240crawler]

Try running some sort of exhaust. Nissan engineers did not desgin this motor to run open header. The closer to stock you put your car, the easier it will be to diagnose any problems. Just my .02

[240sxracer20]

I have ran the car for a season and a half without the exhaust and had no problems up til now. Thanks for the idea though, do you think something as simple as a cherrybomb would help or do I need to get something more than that

[240sxracer20]

After doing some additional research I went back to the drawing board and checked my grounds. When I put the new fuel rail in I forgot to attach the ground nut for the fuel rail so I did that and now it won't start at all and it is dumping fuel directly out the exhaust on the ground. I am desperate PLEASE HELP!!

[InsanityInc]

After doing some additional research I went back to the drawing board and checked my grounds. When I put the new fuel rail in I forgot to attach the ground nut for the fuel rail so I did that and now it won't start at all and it is dumping fuel directly out the exhaust on the ground. I am desperate PLEASE HELP!!

what "ground nut" are you referring to?

[240sxracer20]

on the bottom side of the fuel rail, below the fuel pressure regulator. It may not be a ground but whatever it is it sure seems to have screwed things up