Quote Originally Posted by BillBoost37 View Post
Wires and plugs were changed by the owner.
Aren't you the owner? I see it was the previous owner from other posts. Just goofing around

I also think the boost gage quit working when the check engine light came on.
The gauge and light are not connected. Check that the MAP sensor is connected to both it's plug and vacuum line. It is possible that the misfire/knock is bad enough that the pcm is not allowing boost.

My buddy says that #3 cylinder has 100% leakdown.
Meaning .. it will not hold compression? If so, you have a problem in #3 that might look like the below pics. Might have a chipped piston.
No compression


And.. missing piston
I'll check the vac and connector to the MAP. I have about 70 compression on cylinder 3 and 120 on the other 5 cylinders. 70 is on the line of acceptable. The leakdown on cylinder 3 is 100 meaning that I've got a valve or something that's causing the problem. Could a valve seal or heavy carbon on a valve in cylinder 3 be causing the problem? Next I think is a carbon clean to see if carbon build up is the problem. I just want to eliminate everything possible before removing the head.