Montreal_RX7_Eve

Everyone,
I was changing my spark plugs and noticed the below. Looking at the workshop manuals looks like the knock sensor. The wire doesn't seem to be inside, however I have tried to move it and its solid.
Is this normal or should I have it replaced?

EFS.O

Thats indeed the knock sensor,but the pics are to blurry to tell if its ok.Try to take pics again,but this time use the "macro" fuction on your digital camera.

saxyman990

There is a gelatin-like oil inside the knock sensor (to keep it more stable). A typical sign of a failing knock sensor is oil leaking out of it. Yours is shot, replace it.

-Rob

DVSseven

What Will The Faulty Knock Sensor Affect?drivability?

saxyman990

It's more of a safety measure, although it is possible that it could affect driveability. The stock ECU uses the knock sensor as a protection method. Once the measured knock reaches a certain level, the ECU will pull back timing to protect the engine against detonation. Obviously, a bad knock sensor could give the ECU erroneous information.

-Rob

Tim Benton

iTrader: (1)

Rob is indeed correct, replace it. Without the goop in it, chances are it will pick up more vibrations as engine knock noise that would otherwise not be present in a properly functioning sensor. With it thinking the extra noise/vibration present it will retard timing and your car won't make as much power or be as smooth as it really should.

Tim

Montreal_RX7_Eve

Thanks for the info, I Not in the mood to send it off to a Mazda dealer, how difficult is it to replace the sensor? Is it as simple as changing the spark plugs? Do I also have to replace the wire as well?

RotaryResurrection

iTrader: (8)

The sensor IS the wire. Follow the wire up, it plugs in to the engine harness down in the mess of crap, beside the purge solenoid, behind the alternator area. UNplug the wire, snake it out of the rest of the stuff so it's free, use a large adjustable to unscrew the hex sensor from the block, and reinstal the new one...simple as that.

You might have to remove some BS to get at the actual plug, though, if your car is still stock emissions/sequential.