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Diagnosing Problems and Troubleshooting
Check Engine Light
Software in the EM-5 can detect some but not all problems with the following sensors:
MAP sensor: Power or ground connections, broken or intermittent.
Engine and air temperature sensors: Open or short circuit.
Hall sensor/RPM error problem: Caused by missed magnet or vibrating hall sensor mount.
Low battery voltage: If below 12.5 volts, will turn on the LED.
Lean warning(if enabled): If lean mixture occurs at high throttle for 2 seconds.
Check Gauge modes for “ERR” readings to see which sensor has a problem.
RPM, temperature, MAP sensor errors, even if occurring for a very short period of time, will leave the check
engine light turned on so the user can see there was a problem. You can attempt to clear the error and light by
pressing the +10 button in Gauge1 mode, and if the light stays lit, the problem still exists. If the light turns off, the
problem may be intermittent and you should check electrical connections at the faulty sensor, or check hall
sensor alignment if gauge mode shows an RPM ERR message. Never fly the aircraft if the check engine
light stays on after starting and the battery voltage is above 12.5V.
Low battery voltage will not lock the light on, instead the light will turn off when the battery voltage goes above
12.5 volts. It will be normal to have the light turned on while the ignition is turned on but the engine is not
running, since battery voltage is usually under 12.5 volts.
Some problems cannot be detected such as MAP sensor broken signal wire. Just because the LED is
turned off doesn’t mean everything is good with the system. SDS cannot detect faulty O2 sensors. SDS
cannot detect all sensor problems.
Water entering the computer can be a common problem with improper installations. Remove the lid of the EM-5
and inspect the inside for water, or corrosion. Water, which has dried, leaves a white residue on the circuit
board. Water may still be present under or inside connectors, which will cause random symptoms and running
problems. The EM-5 may operate fine once dried out or may need to be sent in for repair.
The four gauge modes permit monitoring of the primary sensor inputs to the EM-5 in real-time. Rpm should be
stable, agreeing with the factory tach. Spurious rpm readings usually indicate ignition or triggering interference,
or a Hall sensor problem. Don’t attempt to fly with unstable rpm readings or RPM ERR codes displayed in
the programmer.
Manifold pressure should increase as the throttle is opened at a given rpm. Opening the throttle should increase
the TP number. The TP number should not change if the throttle is not moving.
Engine and air temps should roughly agree with the ambient temperature if the engine has been shut down
overnight.
Switching to gauge 2 mode allows you to monitor the mixture knob position. It should read 0 at the straight up
position. You should be able to get the reading to change from -49% to +49% by turning fully to both stops.
In Gauge 2 mode, acceleration pump operation is verified by snapping the throttle open. The AP number should
rapidly increase until movement is stopped then the number should rapidly decrease to 0 again. The AP number
should always be 0 unless the throttle is being moved. Rough running and a fluctuating TP or AP reading
without throttle movement indicates a TPS problem usually. Don’t attempt to fly with unstable TP/AP
readings displayed in the programmer.
When encountering problems which can be identified to be linked with a specific area or function, always go to
that section in the manual first and re-read it.
Symptoms- Fuel Problems
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