OK guys and gals, need to see if someone can help me figure this out. I've got an '89 GTA with an L98. Just noticed this evening that I'm getting some pre ignition at high RPMs. The specific symptoms I've noticed are as follows: I can be cruising at about 50 MPH, and then push it to the floor. Acceleration comes off nicely, but with a bit of knock. As I start to get up to about 60-62 mph, the knock gets heavier, and continues to get heavier through about 75-78 mph after which it slacks off until by the time I get to about 85 mph it's back down to an almost unnoticable level. At this point in acceleration the engine is at about 42-4400 rpms.

I noticed this while driving at normal operating temperature. Oh, and the car has got about 170K miles on it...but the top half of the engine has been pretty well rebuilt...new intake manifold, new injectors, pretty new plugs and wires.

Any thoughts?

 

Knock sensor disconnected/not working?
Call it pinging or detonation, not pre-ignition. Pre-ignition very bad, make loud banging sound like someone hitting engine with hammer. It causes severe engine damage in less than a minute.
Check/change the knock sensor or retard the timing.

 

OK this may be a rather foolish question...but where should I look for the knock sensor? Can't seem to find it in my repair book anywhere

 

Passenger side coolant drain hole on the engine block.

 

haha bottom of the engine then....oh don't i love those jobs. I'll replace it and advise you all of the results.

 

Hint: When cold, remove radiator cap, radiator completely full, lay a ziplock bag across the opening and screw cap back on real tight.
When you remove the sensor, coolant won't come pouring out; more like gluk,,,gluk. You won't have to get a bath.
EDIT: don't forget to take the bag off when done...