350 TBI: Scanner Shows Knocking on Acceleration

[studigggs]

1990 5.7 TBI. So I just picked up an MT2500 scanner and have been playing around with it. I notice that the knock sensor is going off whenever I accelerate (even with mild throttle). Is this normal? Engine runs smooth, no CEL, no modifications from OEM. I'm guessing this is the way its supposed to work by retarding the spark in real time, but didnt think it would be happening that often. Thanks in advance.

 

[evilunclegrimace]

Are there any codes? Is the knock sensor wire connected? Have you verified the base timing? Checked the fuel pressure? Is the EGR operating correctly? Have you cleaned the piston tops? Is the catalytic converter plugged?

 

[PlayingWithTBI]

A loose exhaust pipe can cause KCs also. Your knock sensor has to be the one for your engine and year, if not it will give you false counts. Pull a couple spark plugs and see if they have any dark pepper like specs on the insulators, if so you have detonation. If not you probably have false counts.

 

[someotherguy]

Have you verified the base timing? Checked the fuel pressure? Is the EGR operating correctly?

Especially these ^^^

A loose exhaust pipe can cause KCs also. Your knock sensor has to be the one for your engine and year, if not it will give you false counts.

And especially these ^^^ also, the knock sensor is specific to what transmission you have.

#1 of all though check your base timing. Zero degrees BTDC with the engine at operating temperature and idle. Even the seemingly conservative 2 degree bump that many TBI guys try will cause knock counts on most engines.

Richard