Code P0325 on Corolla 1997. Knock sensor malfunction.

HI!

I own a Corolla 1997 DX 137K miles on it, and the ligh ¨Check Engine¨comes on last week.

I replace the knock sensor, and inmediatlythe light went out.

After 15 minutes (driving 10 miles) the light came back again.
I unpluged the battery and restart. And happen the same, after 15 minutes the lights comes on, then scan and P0325 code emerge.

I know the knock sensor is detecting the ¨knock or ping¨but I dont know what is causing it.

I woul like to know exactly what to do. This car is not giving the 30 MPG that should be. It´s about 20 MPG even on highway.

Driving up on hills 20 degrees inclination at 70 MPH, there is a lack of power and the speed goes down very fast (more than comun lack of power) for this car.

Please help me and thanks in advance.

MAF sensor?
Fuel filter?

could be! did you do any further testing?

I did clean the MAF (internal wire).

The light ¨check engine¨ went out. But, after 1/2 hour, it came back.

I did re-set (unpluging the battery) and happen the same,, , the first 10 min (no light).

NOw is on again.

PS: I can heard the knock noise if i get close my head to the engine.

well if you have an engine knocking noise then i'd start my diagnosis there! if the engine is knocking and you have a code for a knock sensor then the sensor is likely doing it's job! it's telling you the engine is detecting a knock.

OK,

What do you think could be the causes of this knocking?

Why it was corrected as soon I clean the MAF sensor and then fails again?

What else I should do?

Car is low MPG as should be.

Please help.

lean fuel mixture! if the maf is left unplugged does the engine still knock?

I will try.

It means to:

1) Unplug the MAF arness sensor.

2) Start the engine.

3) Check for knock noise.

Am i right?

Thanks

yup!