my knock sensor appears to be working whereas it reads a few knock counts usually at startup which ive found to be fairly normal. the issue is, i am hearing pinging at wot runs in the med - hi rpm range. i could swear its detonation but the sensor shows no knock. im really wondering what this could be.

 

anyone?

 

dude, I am and have been experiencing the same thing for a long long time now. CAN ANYONE ELABORATE ON THIS??? I have replaced the fuel pump as well as the gas tank as I suspected I was losing fuel pressure at wot. Have yet to swap the injectors, but I keep hearing this ping at WOT and it has been over a year since I have really been able to get on my car without fearing that I toast something beyond repair. Anyways, if anyone can help me, it would be greatly appreciated.

Will

 

I'd pull your plugs and check for signs of detonation or preignition to be sure of what it is. The factory knock sensor is only designed to pick up a very narrow frequency range, and cannot pick up certain kinds or intensities of detonation. Aftermarket modifications such as aluminum heads can also change the frequency of the knock, making it undetectible to the sensor.

 

Pinging at mid, and WOT is an indication of preignition, where carbon in the chamber remains hot enough to light the fuel during the compression stroke, but before the spark timing. If you've ever overheated an engine this is what you'll hear. An engine operating at normal temperatures, with the right octane level, and a clean chamber, will not ping.
One of this has changed in your engine:
Air/Fuel Ratio(running rich is known to increase carbon deposits in as little as 30 minutes, I'm not talking spoonfuls) which all engines do in WOT.
Compression (intentional, or otherwise) i.e. carbon build up.
higher operating temperatures (timing)
Octane level (non-brand cheap fuels are not consistant, and don't add detergents to clean the engine.)

Try adding an ocane booster, and back the timing 2°, and see if it helps.
Monitor the O2 at mid-throttle (should bounce between lean & rich.)
If it running rich, reset the ECM and see if it's still rich, and countinue to monitor, if it returns to rich, determine why.
I'm a Fluid FLow Lab Technician, but not an engine technician, much less certified, I work at a Shell Research Center, and have access to a lot of information to verify what others say, and what's I find on the web, but testing is the only why I convince myself of anything.
IF your not using a fuel with additives, please do, your engine, and invironmentalist will thank you.

 

I always heard running alot of fuel additives was bad for things like the cat and would contribute to them failing before their time. I used to run STP and the car ran worse with it in the tank than w/o.

Will

 

ok perhaps what im hearing isnt knock. the plugs look damn near perfect. no signs of detonation at all and they look like there's some more room for timing advance. car runs slightly rich in a couple cells but the overall tune is pretty good. im beginning to think what im hearing might just be normal engine raspiness at the high rpm or maybe hitting a frequency that is making the headers ring. only other thing i can think of would be valvetrain noise but it doesnt really sound like that to me...

 

To clarify, I wasn't referring to aftermarket additives.
The only difference between brand name fuels like Chevron, Texaco,...etc, and non-branded fuels, other than the proprietary formulas (which are also additives) is the detegrents which is the only reason I buy Shell, Texaco, or Chevron.

To me the performance and life of my engine is more important than a $80 catalytic converter, a rich A/F is just as detremental to a catalytic converter as additives.

If you have an idea as to what part of the header is ringing, you can apply heat wrap (for a short period of time) to deaden the ring, but don't under any circumstances forget to take the wrap off after you done a test run.

 

You could also brake torque to the point right before the tires break loose, and hold it for a few seconds. Usually thats enough load on the engine for it to start detonating if it's doing it.

 

ok, as a test, i took out a bunch of timing and sure enough it stopped the noise, so im guessing it was probably preignition after all. now, that leads me to the next question which is, why isn't my knock sensor picking that up? the k/s will detect a few counts at startup but it never ever hears any actual engine knock when its occurring, not even one count. i think i will pull it and clean the threads, retorque and if that doesn't work, replace it. any suggestions?

also, how accurate is plug reading if i was hearing knock and no signs showed on the plugs?

 

Remember ping is before the spark event at low compression, and knock is after the spark event, in either case prolonged severe ping, or knock will damage the spark plug, and engine.

The ECM on startup makes the engine knock as a diagnostic.
Put the passenger side on a jack, or stand, take the wheel off. With the engine running, and a timing light connect to the #1, have someone using a long steel rod, or pipe touching the block near the Knock sensor, and have them tap on the end with a hammer, first lightly and then progressively harder, the amount of timing retard should increase with each tap. If it retards the timing, the noise you're hearing isn't severe enough to be detected by the Knock sensor, or it may be the wrong sensor.