well i was racing a few weeks back a honda civic. the outcome is not important. what happened was when i was racing i ran over some garbage on the freeway. it wound up tearing out my O2 sensor. Immediatly i began to notice that when i drove the car, i had lost all low end torque and was getting real bad gas mileage.
the O2 connector was destroyed so i had to connect each wire by twisting them toghether and sealing them with electrical tape.
low end torque returned immediatly, and the car ran fine for awile. then the problem came back again. the car was REAL sluggish under 3500rpms and would'nt really go anywhere untill the needle passed the 4000 rpm mark. I checked the wire connections and they seemed fine.
I then relaced the whole O2 sensor; same problem. I relaced the CAT, same problem. Cleaned out my EGR vavle, same problem.I even replaced my battery and......same problem I am now in the midst of replacing my PCV vavle hoping that low end torque will come back but i now fear that my car will stay sluggish forever.
Do i need to reset my ECU or something? i don't get it. please guys. I miss my MAX being a little screamer off the line. but for now, i have to baby my car untill i find out whats wrong.
As far as the car under WOT performs, the car seems to do just fine. the car at times seems as though it could be faster than it is now, but it's all up in the air. thanx guys.

 

Knock sensor.....

 

have you checked your fuses?
also is the connector tight at the o2 sensor harness?
plugs look ok?

 

I just replaced the KS 10,000 miles ago. cant be out again.

 

What fuses should i check? all of them or any ones in particular?
i relaced the plugs about 4k miles ago and i'll double check the connections again.

 

how many knock sensors do we have and is it easy to replace??

 

There is only one knock sensor..

It is a pain in the **** to get to on the ve engine..It is in the the valley between the cylinder heads,under the intake manifold...

 

I try to make it a habit of checking all my fuses when something acts funny.
did your exhaust get louder when you lost your low end?

 

actually my muffler does sounds louder for some reason.

 

Exhaust leak?

 

Does your exaust smell like rotten eggs?

~Alex

 

He said he replaced the cat already...

 

As BlueMax said, it probably is an exhaust leak.
Possibly just a blown out gasket , but possibly even worse.
stand next to your car and listen to hear where the sound is coming from.

 

get someone to feather the throttle, and you get under your car to check it out.....