I seem to be running into a voltage problem. When the car is hot and the air is hot, my voltage reads about 13.5. At night it is above 14. It seems to be affecting my fuel pressure, as well. When it is very hot, I only read about 42 psi, but when it is cooler, it reads 52 psi at idle. My fuel pressure dropped below 40 yesterday. When I boost, cooler times, normally I see 60-62 psi. When it gets hot it maxes out at about 52 psi.

How much will the fluctuating fuel pressure affect my tune?
Could it be my voltage regulator going bad? max.

 

Anyone else have this problem?

Any opinions?

 

I don't know, but if anyone out there has an idea, I'd like to hear it.

 

It may be my voltage regulator. I talked to my dealer today and they told me to bring it in when it is hot, so they can check it out. I might need a new alternator.

 

Well as far as the voltage is concerned, heat is an enemy to current flow. The cooler the circuit, the better the conductance. This could be a contributing factor to your +/- .5V

 

I know the heat is affecting it, but the voltage loss is almost 1 volt. This corresponds to almost a 10psi loss in fuel pressure. That is what really concerns me.

 

Possibly heat causing the belt to stretch some and not spinning the alternator to spec?? Try tightening the belt..

 

I have no idea what caused it, but my car died on me once. The voltage fell down and was moving between 10 & 12V, and then fell down and died at 8V. I had to replace the alternator and the battery. Its been running fine since. Now my voltage is around 13v. I talked to one of my friends that works at Nissan, and he said that some of the 350Z's and Maximas have problems with the alternator after a few thousand miles, but he couldn't really explain what caused my car to die.

 

possibly when it's hot, the fans run more frequently which would suck some voltage

 

I think it has more to do with the engine bay heat. If it sits and I start it up, the volts are immediately low, without the fan running yet.