Measuring Engine Exhaust Elbow Height; General Information - Mercury MerCruiser Service Manual

Below is an example of a Live Data screen at completion of the catalyst monitor test. Actual values may differ. Note that the
catalyst monitor ratios indicate that both catalysts may be damaged.
The equivalency ratio is defined as the actual air to fuel ratio divided by the desired air to fuel ratio. Actual/Desired=
Equivalency Ratio. For fuel with no alcohol content the stoichiometric ratio is 14.7:1. For fuel with 10% alcohol, the air to fuel
ratio is 14.1:1. The equivalency ratio eliminates the need to know the alcohol content of the fuel. An equivalency ratio of 1.00 is
neither rich nor lean. Previously, we knew if we ran rich or lean. Now, the PCM 112 provides even more accurate closed‑loop
control because the new wide‑band 02 sensors provide the magnitude of the error not just if it is above or below 1.00. The
difference between target and actual air/fuel ratio is known as Equivalency Ratio error.
The new lambda‑type wide‑band 02 sensors provide temperature information by reading resistance in the circuit.
The new type produces a temperature control much more robust and accurate, resulting in more precise fueling. The sensor
needs precise temperature control for accuracy.
Each sensor contains a heater controller and heater diagnostic chip.
Refer to PCM 112 Diagnostics Service Manual for information about catalyst monitor testing with CDS G3.

Measuring Engine Exhaust Elbow Height

General Information

The height of the exhaust elbows must be within the dimensions specified to prevent water intrusion. If needed, install exhaust
elbow risers to obtain sufficient exhaust elbow height and exhaust angle. Risers must not exceed 152 mm (6 in.) (see the
Available Risers chart for details). Take measurements with the boat in the water. To simulate maximum loading conditions
likely to be encountered, refer to Loading Requirements.
IMPORTANT: The boat manufacturer is responsible for load distribution recommendations. Boatbuilders must communicate
any load distribution conditions that affect the exhaust system, such as maximum occupancy of the swim platform, to the
operator in the owner's manual.
Measurements for all loading conditions must meet the following specifications:
Minimum Exhaust Elbow Height
Model
Sterndrive
TowSport and inboard
90-8M0099748 eng DECEMBER 2015
CDS G3 Live Data screen
© 2016 Mercury Marine
Important Information
56941
Specification
27.9 cm (11 in.)
33 cm (13 in.)
Page 7A-3