I have an 89 Iroc with the L98. When the car is cold, it runs fine, no pinging. Sometimes it hesitates. After it warms up, under acceleration (about 3/4 to full) I get the pinging that sounds like marbles in a popcan. I have checked and rechecked base timing and it is set at the correct value, fuel pressure is about 45psi, tps seems to be right, I just can't figure out how to adjust the precision on the voltmeter I am using. The motor was rebuilt 2 years ago, all the sensors and whatnot were replaced. Except for the injectors. It does periodically throw a code 44, but not all the time.

I remember reading a post about this type of pinging but I can't seem to find it through searching.

Kind of sounds like valve train noise to me..

Anyone have any ideas or suggestions?

 

Evidently the knock sensor isn't working. You shouldn't hear any pinging at all, unless (like you said) it's something else making that noise.

 

Hmmm... ok, WAGes...

Car was running rich and there are carbon deposits in the chambers (reading your plugs can confirm, water in the intake will fix).

Heat sheild loose.

That code 44 is correct.

Do you still have those crappy 'Multec' injectors still? Maybe you should heed that code 44.

Maybe your timing isn't waht you think.

Maybe your cam wasn't installed properly.

Ok, enough... there is a myriad of problems it 'could' be. Try getting some readings of things like fuel pressure and or changes, vacuum changes, etc. when it happens.

 

I need to get my hands on a scanner. How do I test the knock sensor?