Originally Posted by
JeepsAndGuns
The knock sensor is always seperate from the ecm, its threaded into the block somewhere. Its the knock filter I was talking about. Its what recieves the signal from the knock sensor when there is knock, and then sends a signal to the ecm to retard timing. The knock sensor and knock filter are engine specific. On yours, its the squareish shaped flat box with about 4 wires going into it, should be mounted beside or under the map sensor on the right of the intake. (it was on the truck I am parting out anyways)
On the later pcm's (such as the 16197427) the knock filter is part of what is called a memcal. It has the main prom chip, the limp home chip, and the knock filter all in one removable unit in the pcm. The V6 and 5.7 memcals are easy to find, but a 7.4 memcal is not as easy. You could use a 5.7 memcal, and re tune the chip to work with the 7.4, but the knock filter will be incorrect and the knock retard will not function correctly. It could either pick up false knock and retard your timing, hurting performance, or not pick up knock that is there, and then your engine could get damaged.