2000 SSEi Exhaust manifold leak / rattle or pinging ?
I already know I have an exhaust manifold leak, but I have a rattling noise that I cant seem to pinpoint. It happens under light accel when it gets up to about 2-2.5k rpm, at about 3k it seems to go away or the motor noise is drowning it out. It sounds like a heat shield rattling or marbles in a can which seems to be consistent with pinging from what ive read. The car still seems to have plenty of power. I always 93 octane, I did replace the plugs a couple months ago with ac-delco iridium pre-gapped at .60 so I really don't think its the plugs. I do have a zzp pcm that I have also had in for a couple months as well. I'm thinking about swapping my original pcm back in to see if maybe the timing is off ? I heard rumors that the zzp pcm is not the greatest especially in Bonnevilles. Other than that could an exhaust manifold leak cause pinging ? Thanks