[T3] On a 73 T-3 SB fuel injected auto trans pinging

[Phil Hof]

You answered my first thought, which is if the MPS leaks or not.  You said no., so let’s table the MPS for now.

Next, I wonder if your injector tip seals are bad.  This would allow air in, causing leanness in any leaking cylinders (and perhaps pinging on that/those cylinders), but because it’s maybe only one of four, and so far from the MPS, it may not tip off the MPS much to enrichen things, and your “pull the TS plug” enriches it enough to alleviate the pinging, those it makes the other, non-leaking cylinders run rich.

Lastly, I’ve said this before, but the late model breather/PVC is different than the early style, and I hear that faults can cause vacuum leaks that might cause at least some of your symptoms.  If anyone has a good diagram and discussion of how the late PVC system works, we could set this right and eliminate another variable.  Ot just scan the Samba classified and put in the older, simpler, PVC/breather system.

-Phil