Mazda Tribute 3.0 V6 came into shop with No5 spark plug blown out. Head was R and R'd and repaired. Timing chain was refitted exactly as described in manual. Vehicle has miss in No4 and No6 cylinders. Spark, fuel and compression are all ok. Timing has been checked and rechecked and seems ok. We are at a dead end. Can you help?

SOURCE: not sure if my 2005 mazda tribute has a timing belt or chain/ 2.3

what do you need to know

SOURCE: does a 2005 mazda tribute 2.3 having timing belt or chain

a belt

SOURCE: Mazda 323 Has spark, fuel, timing belt ok, does not want to start

check timing belt timing on the cam gear and crank gear. if timing belt has 60000 miles or more. if they dont break first. they stretch enough jump out of time.

SOURCE: spark plugs

You have to remove the intake (and the manifold) just to get to them. They are on the engine like every other car but access is trying because you can't even see them until you start removing the above items. If you still aren't sure where all of this is, follow the plug wires from the coil pack to the plugs. If it does not have wires, it will have individual coils on top of each plug. Unbolt each coil and pull it up. The plug is under it. On your V6, they should be located on the side.
This is very tricky on this vehicle. It is, of course, recommended to take it to a shop. Some special tools may be required.

SOURCE: do timing chains need replacing after 100000kms on

If you are experiencing issues with timing (backfiring, dieseling, rough idling, power loss, etc...) your timing chain might indeed need adjustment or replacement. If your vehicle is working without issues it's highly unlikely.