Ever since my ugly track times, I have noticed a decrease in overall power, in particular at the top end range of my gears. I tried to pull codes but got 0505. and to further test my power theory, I took the max on a safe road to a speed that I will not mention, and it didnt accelerated through that speed the way It has in the past, so I am more confidant now that there is something wrong. i was thinking knock sensor but can that go bad and still not throw a code?

 

maintenance? spark plugs, fuel filter, ect.....
reset ecu wait one day and see if u get knock sensore code

 

You'd be suprised at the gains a new fuel filter, set of plugs and a clean air filter can make.
[UOTE]
reset ecu wait one day and see if u get knock sensore code [/QUOTE]
He doesn't have the KS code he's only pulling 0505. (all OK) Resetting the ECU only clears error codes, it does not in any way reset stored operating parameters. That information can be found in both the Haynes shop manual and the factory service manual.

 

oh
well either way do a 60k tune up and clean ur tb and IAC vlavle while u are at it
in the faq's it tell how to clean iac valve
http://www.motivational.net/ has alot of other maintenance things u can do for cheap
http://www.nissan-accessories.com/PP1.asp?PID=117 has a tunbe up kit u can buy