Hey All,

Ok so here is my issue, I have a 2003 350z, 6spd. I love it. I bought it used in October of 2008, took it for a test drive all was good. In around December when it was fairly cold out, I went for a drive and it felt as if the Horse power went from 287 to 140. I didn't understand what the hell was going on.

I drove for a few minutes, let the car heat up, it even felt as if it was permanently bogged down as if the traction control was always slowing it down, so I turned the VDC off..nothing...once the car got nice and warmed up it was at full horse power again, I didn't know what to think about this.

After a couple weeks I was driving at night, car was running slow as usual off the start, and for some reason i decided to just switch off my headlights. as soon as I did that, BOOM full horsepower, so I toggled back and forth and realized that if the headlights are on its super slow when cold, but once its all hot and ready to ride it doesn't matter if the lights are on or not, full power. So depending on how cold it is if I leave the headlights off from the start it runs great, I have to wait ti flip the lights on till the car is hot. STRANGE! As far as i know its all stock wiring and lighting aside from the stereo but that was put in after this issue came about.

So i thought maybe it was the battery, so I changed it for a high performance battery, still no change, cold slow, warm fast. So next step was the alternator, I even got them to put in a higher output in AMPS alternator, nothing, but my stereo was booming great.

*I had asked a few friends who are mechanics, one said it could be an O2 sensor, which I have yet to change. Does this sound right?

**another friend said it could be a bad ground somewhere, which would take a lot of testing every single wire for a bad ground FML

If anyone has ever experienced this issue or has some input I would be very grateful!!

 

do you have stock tail lights?

 

Moved...

 

I don't, I put on aftermarket LED tails, but the problem happened before I put them on, what the LED tails did was fkd up my cruise control, it reads it as a light is out and I cant use cruise control when headlights are flipped on. Maybe i'll try swapping out the tails to stock again and see if that changes anything.

What led you to asking about the tail lights?

 

swap the tails back to stock, I bet that fixes it. when you mentioned that turning your headlights off fixes it...

 

I'll give it a shot tonight and post the outcome...

 

https://my350z.com/forum/engine-and-...blem-help.html

post 94...

https://my350z.com/forum/exterior-an...using-ecu.html

these threads sound real similar to your problem...

 

Yeah looks like thats the issue, hope it fixes it. I think I want to keep the tails so I want to find out which resistor I need and where to put them...