Vibration?

[Schurkey]

Should hammering on front of pass. exhaust manifold while using timing light cause change in timing?

I would have expected that the timing would retard.

However, someone on this forum--I don't remember who--said that the computer ignores the knock sensor below a certain RPM. That's not true on the older systems, but it sure could be on some of these GMT400 or newer vehicles.

 

[scott2093]

I would have expected that the timing would retard.

However, someone on this forum--I don't remember who--said that the computer ignores the knock sensor below a certain RPM. That's not true on the older systems, but it sure could be on some of these GMT400 or newer vehicles.

iirc, when I was testing mine -93-, the computer would see the signal but wouldn't retard unless the idle was up... Can't remember what idle, wasn't much, but I remember it was stressing me out until I held the throttle a bit open while testing and it retarded then... ...it was easily heard...

Guessing the damper would be too obvious to mention as a possible source of vibration...

 

[Anchor]

I would have expected that the timing would retard.

However, someone on this forum--I don't remember who--said that the computer ignores the knock sensor below a certain RPM. That's not true on the older systems, but it sure could be on some of these GMT400 or newer veh

I would have expected that the timing would retard.

However, someone on this forum--I don't remember who--said that the computer ignores the knock sensor below a certain RPM. That's not true on the older systems, but it sure could be on some of these GMT400 or newer vehicles.

Hey! Don't call me a retard!