* Specific engine model: The 2.9L was used across various Ford vehicles and years, each with potentially slight variations in design.
* Engine wear and tear: Compression naturally decreases over time due to wear on rings, valves, and cylinder walls.
* Testing method and equipment: Different testing gauges can give slightly different readings.
Instead of a specific number, you should look for a range. A good starting point would be to consult a Ford repair manual specific to the year and model of your vehicle. These manuals usually provide acceptable compression ranges for that particular engine.
Generally, you want to see relatively consistent compression across all cylinders, within a few PSI of each other. A significant drop in compression in one or more cylinders points to a potential problem (worn rings, valves, head gasket, etc.). If the compression is low across all cylinders, it could suggest issues with the rings or valve seals.
Without knowing the specific year and model of your Ford 2.9L, I can't give you a more precise answer. Consult your repair manual for the correct information.
