Vehicle Affected:
- 2002 Mazda Tribute 2.0L
Tools Used:
- Vehicle specifications
- Diagnostic worksheet
- Scan tool
- Vacuum gauge
- Snap-On Compression Tester, No. MT308JB
- Lab scope
- Fluke Vacuum/Pressure Transducer, No. PV350
- Matco Leak-Down Tester, No. CLT200
(This repair is diagnosed in the Tool Briefing: Diagnosing the root cause of a misfire)
Following the repair procedure outlined in AllData, we removed the cylinder head and had a valve job performed and the head surfaced. During the valve job it was noted that cylinder No. 4 had a significant amount of carbon build-up on the valve stems and valves. This information was valuable because it showed why there was a lower vacuum reading on that cylinder, it was lower because the air entering the cylinder was partially blocked by the carbon. Since we had a pulsation in the engine vacuum readings, we took extra care to make sure the valve springs were within specifications. We found the intake valve spring was weak on cylinder No. 2, which would cause the issue. After re-installing the cylinder head and replacing the ignition components due to wear, the engine ran well with no misfires.
