what is a knock sensor and what does it do??

white90sc

Registered User
hello,
what does the knock sensor do and how do you know if its going bad.

also where is knock sensor placed on that engine?? where do i find it..

thanks
Jerry
 
knock sensor

The knock is a sensor that "hears" when the engine is detonating, or prone to detonating or "knocking." The computer then retards or advances the timing to prevent pre-ignition. I'm not exactly sure how you'd check on our engine, I'd have to goto my repair manual, but I'm sure you could check the resistance on it to a certain value. This is a huge issue though, considering some poorly made knock sensors are known to be set of if a rock accidently bounces off the block, or if you have a loud a/c condensor, etc. you get the idea.
------Dylan
 
ok the my problems

Hello,
I'm having a problem with my 90 sc aod at higher RPMs when i gun it and it gets around 4000 the check engine light comes on and my car seems doggy, then at 4700 the check engine light goes off and runs great and you really can fell it kick in.

Stuff that i have modded are FLowmasters, ic fan, 10% odp, cold air dam intake, bypassed the coolent tube on the stock troddel body, b&m shift kit, steal ideler pulleys, and i just changed the supercharger fluid, and replaced the iac valve, and Dis.

I would love to here from you guys the is really bugging me!

Thanks,
Jerry
 
the knock sensor tells you when someone is at the front door.

Sorry, I just couldn't resist that one. :)
 
The knock sensor is a big piezio microphone that screws into the block waterjacket just above and in front of the starter. I am most familiar with them on my Mustang SVO 2.3 turbo motors where they can be tested by tapping the block (or intake on 2.3) with a hammer and watching the timing back of. On the SVO we can adjust the timing and set it up to run without the knock detector funtioning. It is normal for it to false trigger a few times per minute so your best performance is with it disconnected, although the wise man leaves it connected in daily street driving.

It is not a resistance type sensor I believe, but generates its own voltage like a O2 sensor. I'd try the knock on the block test with a timing light. Mine is working but failed to save my #6 cyl from detonation damage before I bought the car. After rebuild I was getting engine surging at 4000 when hot. My test was to unplug ithe knock sensor, it knocked. Cure was a 180 thermo.

Steve Best
 
MAKE SURE that you replace it. When I first bought my SC it didn't have one at all. No piece of it or nothing-just gone. Much like my engine now. It is found by the passenger side motor mount. The motor ran for a while and without warning-I believe that I lost my engine to a $40 sensor.
 
Back
Top