I have a 94 22RE that has a knock when I let up on the accelerator during warm up. When the engine comes up to operating temps (5 minutes), the knock goes away almost completely. I read through a bunch of related posts, but can't differentiate between piston slap, worn bearings, wrist pins, or valve noise. Anyone suggest what this noise is most likely from?

 

In first 5 minutes, piston warms first. So, sounds like wrist pin or excess piston to wall clearance. You can figure out which cylinder it is by pulling the plug wires one at a time and cranking the engine. Get a second person to help. If its excess piston to wall clearance, drive it. You will be dead before it becomes a serious problem.

My $0.02

 

Have you checked the timing? And, are you sure what you're hearing is an actual knock? Pinpoint where the noise is coming from, if you can.

 

Timing is right on. I have gone so far as to advance/retard timing a bit to see if the noise goes away. It changes it a bit, but still present. I will get someone else to dip the throttle while I listen closely above and below.

 

check the valves

 

Other than .008 intake and .012 exhaust, what would I look for?

 

Do you have a stick shift and does it happen only in certain gears? Thinking it could also be tranny noise, like a bad synchro, worn gears. I only mention it because I have a similar noise and I'm pretty sure it's not a worn wrist pin or out-of-round bore because I just built my new engine last year and the whole short block is only 8,000 miles old.