Has anyone had a Motorvac cleaning? They hook a machine up to the fuel lines and mixes in cleaner with fuel and let it idle for like 30 minutes. It is supposed to clean all the carbon build up from inside the top end.

In my 89, my scans show that I get knock counts on acceleration that I haven't been able to figure out as everything is tuned up and everything checks out fine. I've done a few seafoam treatments, but I've read you have to do something like a Motorvac cleaning to really clean up the carbon.

The PO put in the wrong injectors and it ran rich and would carbon foul plugs. So, I was thinking the knock could be from a build up of carbon.