Hi all,

I have a 94 sammy 1.3TBI 130,000mi and it's driving me crazy.  I have what sounds like preignition when I accelerate.

-Hot or cold does not matter
-RPM does not matter

This is what I have tried so far...

-Disabled the timing advance and retarted the timing
-thicker oil (maybe a engine knock)
-no engine codes are present
-MAP is okay  (if i disconnect it to open loop it still makes the noise)
-High octane gas.

What I might do next...

new spark plug wires
new cat converter (maybe causing the noise but it's a long shot)
engine rebuild (maybe carbon build up)

That sounds like a weird one.  Can you get the noise if the vehicle isn't under load, and your just revving it up from under the hood?

Once and a while I can get the noise when not under load but not all the time.  I thinking it's a rod bearing or something.

I'm thinking carbon buildup ...

Would be interesting to know compression numbers, and you could always try to seafoam it ...

Have you taken the time to check the valve lash?

I have checked the valve lash it's good.  Carbon buildup is an option but I did seafoam it and it made no difference at all.  The compression is 150psi in all cylinders a little low but should still be okay.

What should I try next??

Are you sure it's a pre-ignition "ping" ...

My chevy 2500 had a rattle from a loose heat shield that would "ping" only under acceleration (motor torque would shift things just enough to "ping"). I only managed to find it when one day it was off-camber and would "ping" sitting at idle.

Found it!  It was a cracked piston.  I caught it in time so I'm able to rebuild.

Lucky.