i lost alot of power ,went to nissan and they said nothing is wrong (no codes). later i had the car dynoed at 181hp- 208ft-ibs i'm going to change the plugs next. anybody have an idea whats wrong?

 

how many miles are on it? is the dyno jagged or it pretty smooth? any areas of drop off or it just low throughout?

 

yeah it's pretty jagged and starts to drop off around 4,500 rpm.

 

sounds like your variable intake isnt opening up. i would check for lines that may be kinked. although even before it opens up, it should be pretty smooth so replacing the plugs is not a bad idea. without the variable intake opening up, it can make a huge power difference. i unplugged mine to check to see if it was operating ok and it was a dog up top.

 

could it be a clogged fuel filter?! Or u need fuel injector service- clean out your intake manifold

 

that could be contributing to it as well but its odd that it starts to fall when the VI is supposed to kick over.

 

here's the dyno .

 

ack.... who was running the dyno? That looks jacked up... It's plotted vs speed rather than rpms...

Anyhow, it doesn't really look like an ignition problem... it seems like you have some major power loss at the point your variable timing kicks over... it looks like it's not switching.

 

just looked at it again... it's plotting STD numbers, not SAE corrected? What were the conditions under which it was dyno'd? What's up with the plots that are broken up? I'd take it to another dyno place just to double check.

 

the air fuel ratio chart shows my max as 17.5 at 3300 rpm then it skydives down to 11 at 3500 and hovers around 11 to 12 until fuel cut off.

 

17.5? was the car at WOT at 3300 rpm? Was it a spike? If not at WOT, then the O2 sensors should keep the AFR at ~14 or so... the 11 or 12 until fuel cut sounds normal... maybe slightly rich for NA, but not really of much consequence... not enough to cause the power loss