Any engine control systems that use electronic throttle must have strict position error detection for obvious reasons.  The OE system uses two separate sensors for pedal position, as well as two sensors for actual throttle position.  This ensures the ECU can validate and trust the inputs.  If there is an error in validating the position, the system can be set up to react a number of ways.  Shutting down the throttle system is the obvious answer to prevent unwanted acceleration (especially on track).  

With more complicated engines, the aftermarket ECU system must still rely on the same sensors for safety.  Diagnosing these types of errors can be complicated (even with a factory ECU), but if your installer develops a good troubleshooting logging set, these systems can be diagnosed quickly and easily.  

Attached is an example of a failing pedal position sensor using an #emtron #kv8 ECU.  


The top graph shows drive by wire target vs actual throttle position.  If the system is working properly, then these lines should draw on top of each other (except during quick changes).  Looks good as you can see.  

The second graph shows the difference between throttle position sensor 1, and throttle position sensor 2.  0% is normal at all times since there should be no difference between the two signals regardless of the actual throttle position.  With a closed throttle, both should read closed.  With an open throttle, both should read open (and in between). This is how the ECU validates the position.  The graph is blank, verifying there was no error over the entire logging session.  

The third graph shows the difference between pedal position sensor 1, and pedal position sensor 2.  The function here is the same as the throttle sensor comparison.  As you can see, there is a lot of activity in this section immediately reporting that there is some sort of issue.  

The error in comparison is only a few percent (circled values on the right), but the ECU is aware of this almost instantly.  This demonstrates (and inspires confidence in) the Emtron ECUs ability to automatically react to to potential problems.  

A proper ECU logging setup will also make diagnose very simple and painless.  The Emtron log viewer allows you to create new tabs for parameter display (see DBW tab section on top).  I was able to determine a potential issue within seconds of downloading the ECU log.  After collecting and reviewing this data, a plan for furthering diagnosis is easy.


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