Is There A Way To Bypass The Knock Sensor On A 1987 GMC 350 EFI Non Roller Cam Engine

Posted in Crank, Oil and Piston | Asked on Jun 4, 2010

I am installing a noisy timing gear set and i dont want that the knock sensor to “pick up” the transmission delay and the timetable, in which I said it was doing was. Is there any way, only the fools knock sensor into thinking its fine. I was told that only the male can not cannot too. Any help? Ideas?

There are 2 Answers for "Is There A Way To Bypass The Knock Sensor On A 1987 GMC 350 EFI Non Roller Cam Engine"

  1. bbking48507 says:

    All the sensor needs is to be grounded to the engine block. when the knock sensor detects knock, it produces an AC voltage. The computer supplies 5v dc to the knock sensor. The knock sensor has an internal resistance of about 100,000 ohms. The internal resistance brings the voltage down about half, to 2.5v dc. The knock sensor produces an AC voltage that rides on top of the reference voltage in the same wire. The computer can then read the ac voltage and retard the timing appropriately to control the knock. It seems to me that as long as the knock sensor is grounded to the engine block to complete the path for the 5v reference, it shouldn’t ever detect any knock, therefore keeping the timing from retarding. But remember, the computer will not be able to protect the engine from engine knock that is inaudible.

  2. electron670 says:

    This sounds like a wonderful way to destroy your engine. The knock sensor is there for a good reason. There is a specific frequency created by spark knock or detonation. The sensor detects this and tells the computer to retard timing to save the engine. If the computer cannot detect detonation, it will overadvance the engine timing. You WILL lose power and pound out the rod bearings from detonation. I have seen Chevy 350s with ruined cranks from disconnected/disabled knock sensors.

    Don’t believe me? Disable the sensor, run the truck hard for a few months and let me know what happens.