The Stovebolt Site Forums The Shop Area The HiPo Shop Still working on the TPI knock sensor

OK, I've been down this road before and based on the last thread I was going to try to mount the sensor on the motor side of the mount. But as I was looking things over it hit me. I placed this shiney new cover over the old fuel pump opening and..... well do you think the sensor would work there?

Try it?

The location is at the front instead of in the middle, and lower down on the motor. Those issues make me wonder if it will sense as quick as it would in a stock location.

But I bet it would work well enough.

Well, to think about it. If I remember correctly, on my 1990 454, the sensor was on the middle of the block, low, between freeze plugs. So you have sensor, cast iron, void full of antifreeze mix, then the cylinder wall. A bit of stuff between the sensor and where the knocking would be happening.

I believe on my TPI Corvette its higher, closer to the head. Since I was about to pull that car into the shop I'm going to look to be sure.

But again, I think it would only be a tiny bit slower to react and probably not a problem.

I've not tried to reprogram one of these things. Is knock sensor sensitivity a programmable parameter?

Not sure if it's programable. If it needs to be closer to the head, how about the old temp sending location? I just plugged it up because the temp sender is mounted in front of the intake.

Why not put it where it belongs, in the coolant drain hole? The factory installed a few million of them there, with no problems.
Jerry

Thanks Lincoln, didn't know that's where it belonged. But therein lies another problem. the block hugger header is right above the plug leaving no room for it.

OK, just move ahead or back a short distance, and drill & tap another hole, approximately the same distance above the oil pan rail. There's nothing down there that you can get into trouble with, as long as you don't drill through into the crankcase. The thread size is 1/4" NPT (National Pipe Thread). You could also weld or braze a 1/4" pipe coupling onto the fuel pump blockoff plate, and screw the knock sensor into it. It's just a piezo-electric crystal that generates a voltage when it hears a spark knock. The computer retards the timing 3 degrees, and listens for a knock again. This procedure continues until the knock goes away, or the timing retards to approximately 10 degrees after top dead center. BTW, a noisy valve lifter will fool the knock sensor. I chased a sudden power loss at highway speed for about 3 days, until I isolated an intermittent collapsed lifter that was retarding the timing. A valve adjustment cured the problem.
Jerry

I agree with Jerry. Put it in the side of the block. Put a 90 deg elbow in there to clear the block huggers.

no.

The knock sensor will work anywhere on the engine block, or the cylinder heads you choose to put it. Sound waves travel much faster through cast iron than they do through air, and the speed of sound in air is over 600 MPH. A few inches up, down, or sideways won't make a measureable difference in the operation of the sensor. The suggestion about the elbow is a good one. Just use a "street ell" with a male thread going into the block, and screw the sensor into the female thread. You can turn the ell to get the best clearance to the header. Of course, the simplest method would be to trash the headers and run the original exhaust manifolds. Unless you're planning to run above 3,000 RPM routinely, the headers are just for looks anyway.
Jerry