I have replaced my knock sensor my spark plugs and my fuel filter, my ecu is throwing the 0505 code but my car still has that wierd feeling durring acceleration assosiated with the knock sensor, any thoughts on what else could be going on with my car.

 

Have you replaced your O2 sensors? Just a thought...if you're talking funny acceleration when you're NOT wide open throttle, then it could be tired O2 sensors...
-Chad

 

When's the last time your cleaned or replaced your air filter?

 

How badly can this affect peformance/acceleration? I've cleaned out my HKS sponge filter twice but it just doesn't seem to be clean enough.

 

My old Maxima (92) ran like poo until I changed the air filter, fuel filter and plugs. Then things were peachy.

 

Are you running 90+ octane gas?

 

I do need to clean my filter its been a year now and probably needs to be cleaned, I run 93 octain, and I probably need to replace my O2s but I thought that you should leave them alone unless they throw a code.

 

I have the same problem, eve though I have installed new spark plugs, fuel filter, PCV valve, O2 Sensors. I have not yet replaced the knock sensor.
Just by curiosity, have you reset your ECU?
I have read that if youchange the knock sensor and do not reset the ECU, the car will have the same behaviour.

The symptoms are:

- Sluggishness,
- Weird accelerations (almost a random rocking)
- Feel (some times) like there is wind against you when accelerating
- Motor roars like it should be pulling faster but the accelration does not match the motor sound.
- Could be mistaken with a clutch slipping.

 

I have a problem with my acceleration too... Its slower than an M3's. Okay... Lame but oh well.

 

I reset my ecu but as long as I'm WOT the car is fine, in fact I had it at 140 mph this weekend, so I'm pretty sure my clutch isn't slipping, I'm begining to thing it is my O2s but they can wait the car does fine otherwise.

 

Blocked exhaust? I had weird acceleration when my flex section had colapsed. Now with the new flex the problem is gone.

 

How can you tell if your flex section has collapsed?
-Chad

 

Also check to see if your brakes are dragging. Put the car up on jack stands and turn the wheels by hand.

 

The only way to tell if the flex has collapsed is to look inside. Disconnect the y-pipe from the cat and look in.