I've got three odd problems. The first doesn't seem related to the other two. All are intermittent, and not weather dependant. In addition, when they aren't happening, the car runs perfect. 100k miles.
The first is when I start the car cold, the radiator fans turn on and off at random until the car warms up. Once the car is warm, they work as normal, turning on and off as temperature rises and falls. Thermostat is new. This problem is probably the least occuring of all of them. This almost never happens with the other two problems.
The second is the most occuring. It usually, but not always occurs when the car has been recently driven. I notice it often after class (it sits for an hour and a half after being driven). It rarely occurs when the car has been sitting for a period. The engine starts the first time, but runs rough, and blows black smoke. The exhaust smells of gas. Revving the engine between 1000 and 3000 is rough, and it runs better in the higher rpms. The problem always goes away within 10 minutes (usually 3 or 4), and when it does, it does it instantly. It goes from running bad to running perfectly. It never dies like this, just acts like the ecu is pumping in too much gas.
The third is pretty much like the second, but doesn't occur very often. The engine won't start reliably, and when it does, it runs like the second problem. Sometimes it won't start at all, and it has to sit for about half an hour. I used to try it every minute or so until it started, but I have recently just been pulling the ecu fuse. This way, it starts the first time, runs rough as the computer is picking up the new parameters, and then runs fine.
I've taken it to nissan (a brand new dealership with a wonderful shop), and they couldn't find anything. I at first though it might just be a bad ecu, but I don't think the car would run well at all if it was. I'm now starting to think it is a sensor, loose wire, maf, I really don't know. Any ideas? Thanks for reading, Steve