7.3 Ignition Settings 7 ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL
generates a small voltage (~1 volt), much like a microphone. As an example, some Corvette knock sensors (GM
PN 1997562, 1997699, or Standard Motor Products KS45, KS46, KS49, or KS117) have a design frequency of
5200 Hz, and they produce a signal between 4800 Hz and 5600 Hz.
Most Bosch sensors with a hole through the center are wideband knock sensors, adaptable to many engine
types.
The sensor should be mounted near the top of the engine block, as close to the center as practical. Do not
mount it close to noisy components such as the fuel pump or cam shaft lifters. Mounting the knock sensor in the
cylinder head is not a good idea because of valve train noise. Finding a suitable location of the sensor is crucial.
Wherever possible, use the location specified by the manufacturer for that engine family.
Ideally, you will be able to find a suitable threaded hole in your block to which you can mount the sensor. If not,
an alternative is to drill and tap the block, or thread a steel adapter to accommodate the sensor on one end and a
stub with the thread to match those in an existing pretapped boss in your block. Note that it may be necessary to
change the sensor location if you cannot isolate engine noise while allowing MS3Pro to identify knock.
If you choose to drill and tap your block, choose a thick area of the block with a boss that is at least ¾" (19 mm)
thick. Drill a ½" (13mm) hole. The hole should be 0.500" to 0.625" (13 mm to 16 mm) deep. Make absolutely sure
that it is safe to drill a hole this size - a poorly placed hole can trash the engine block.
The GM knock sensors have a 3/8" NPT thread. Tap the hole with a 9/16" UNF starter tap. Go in 4 turns of the
tap to begin with, clean out the chips and try the sensor for fit. Keep tapping one turn at a time until the sensor
threads in 4 to 5 turns with hand pressure. Stop tapping when the sensor will screw into the hole 6 to 7 threads
with a wrench. Note that the thread on the knock sensor is a tapered thread.
The Bosch sensor can be more simply attached by bolting it to the block. Two wire versions usually use a
standard EV1 style injector connector.
The knock sensor settings screen lets you adjust how the MS3Pro handles knock input.
7.3.7.1 Knock sensor settings
• Knock control: Allows you to change the way the MS3Pro applies timing retard.
– Disabled: do not use knock feedback for ignition advance control
AMP EFI MS3Pro manual version 1.202, firmware 1.5.0, 4/21/2017 Page 172
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