1992 240sx dead zone 4-5k

[BoostCreepr]

its a coupe all stock at the moment. It has a new coil, plugs, wires, cap,rotor, fuel filter and clean fuel sock. When accelerating in any gear between 4-5k rpm the car loses its pull and slowly revs through the rpms then after 5 maybe 5.5k it kicks back and pulls like it should. Not sure what would cause this, any ideas what i should check next?

[bcar240]

My car had a similar problem at a different rpm range. For me it turned out to be the fuel injectors. They were sticking or not metering correctly at a certain rpm range and causing a noticeable lack in power (I could feel acceleration let up) and an audible change in engine tone if I paid close attention. It actually took me a while to diagnose it and it got so bad that the affected cylinders would start missing from time to time (the only benefit to that is that it makes it easier to find out which one is bad by pulling plug wires). In my case I actually had two bad injectors as the same time that would get buggy at different rpms, making the symptoms very confusing.

I replaced all the same parts that you did, even threw in a knock sensor as well, before I got to the fuel injectors in the "throw parts at it until it works" mode. About 6 months later another fuel injector went bad (older Nissan injectors seem to go out almost like clockwork) and started doing it as well, so I went ahead and replaced the last two and that problem has not recurred in the past 1.5 years.

It's an easy fix, I think I have a how-to around here somewhere if you need one. Just make sure to use lots of PB blaster and make sure you use the correct tools, those guys are probably stuck in there pretty good.