280zx engine problems

[sev0062]

Ok so iv got an 83 280zx na and it was running great for the most part untill recently. It all of a sudden developed three problems. The first is if I rev the engine to 2k and leave it there it will drop 200 rpm and then go back up every couple of seconds. What could be causing this? The second proplem is when I'm getting on the highway and my rpms are in the 3500-4000 range every now and then it will feel as if there is a substantial loss of power and then its fine seconds later. Could this be related to the first problem? The third problem sounds like a valve tick but I just adjusted them and made sure everything was torqued to spec and in tolerance hot and cold. The big difference with the noise this time vs last time is the noise goes away once the engine I warm and has been running for a few minutes. Could this be the injectors being noisy, the lifters being out of tolerance again, or a lubrication isue? Thanks in advance for the help.

[jminer84]

I am new to Z''s but was having similar idle issues. For me it was the Boost Controlled Deceleration Device. I ended up hooking mine up to a 12v source that was only on when the car was on which effectively closed it. Solved my problem.

[nismosilvia]

My car runs like crap without the bcdd hooked up. Clogged fuel filter is often overlooked too.

[jminer84]

My car runs like crap without the bcdd hooked up. Clogged fuel filter is often overlooked too.

 

To clarify, mine was exhibiting the poor idle (idle sticking at high rpm) condition when it was not hooked up. PO had removed some of the harness so I just wired it to 12V when ignition was on. This closes the valve so it no longer controls idle in anyway but is different that not being hooked up at all.