There have been many threads on RPM fade/ low rpm on the Axys chassis both here and on other sites/ forums.
This cause/ effect was eluded to by SheetmetalFab in another thread but I wanted to start another thread in the hopes that it could help someone who was searching to find a solution sooner and easier.
The E-VES system has multiple components which translates to multiple possible points of failure. These components include:
ECU
PWM converter
E-VES Actuator
Relays
E-VES cable
wire harness
wire harness connections
Having a problem in any of these components can adversely affect performance-- typically manifested in peak rpm not being achieved. The service manual will lead you to believe that a code will be thrown for any E-VES malfunction offering quick diagnosis and solution. This is not the case.
A customer brought in a 2016 Turbo SKS with 2000 miles, complaining that the sled would only reach 7600 rpm. He mentioned that it had thrown a code (position not achieved) but that the code was not currently active. I elevated the rear of the sled and, after warming it up, opened the throttle to see what we could achieve rpm wise and whether or not it would throw a code. With no load, we could spin the motor up to 7600, no code thrown, and could watch the E-VES actuator move through the three positions.
When I removed the cable from the actuator, to do the service manual "push-pull" test for resistance and travel distance, the cable came out-- it was broken. This made me think about the E-VES system.
The system is set up where the ECU compares commanded position versus achieved position by comparing the hall effect sensor in the actuator versus voltage values at a given position. The problem with this system is that they are upstream of the actual exhaust valves and also the cable. Without a limiter switch on the actual exhaust valve or the tie-bar, there is no real way for the ECU to know if the intended valve position has been achieved.
There is a cable travel specification--full-in to full-out-- of 16-18mm.
If the cable has stretched, the exhaust valve may not fully open--leaving the exhaust port shrouded-- reducing peak rpm.
What can make this difficult to diagnose is that the ECU may not throw a code if the actuator hall effect sensor reaches it's intended position and the voltages correspond because they are upstream of the actual valves. This customer SKS did not throw a code and yet the cable was broken meaning the valves weren't opening at all.
How many Axys motors with low rpm issues have had the cable travel distance inspected? Are dealers doing this or are they simply using Digital Wrench to perform an E-VES re-learn without physically checking the travel distance?
I may add the cable to the list of components that I swap out at a specified interval (like motor rubber isolators) versus suffering cable stretch/ break performance issues.
This cause/ effect was eluded to by SheetmetalFab in another thread but I wanted to start another thread in the hopes that it could help someone who was searching to find a solution sooner and easier.
The E-VES system has multiple components which translates to multiple possible points of failure. These components include:
ECU
PWM converter
E-VES Actuator
Relays
E-VES cable
wire harness
wire harness connections
Having a problem in any of these components can adversely affect performance-- typically manifested in peak rpm not being achieved. The service manual will lead you to believe that a code will be thrown for any E-VES malfunction offering quick diagnosis and solution. This is not the case.
A customer brought in a 2016 Turbo SKS with 2000 miles, complaining that the sled would only reach 7600 rpm. He mentioned that it had thrown a code (position not achieved) but that the code was not currently active. I elevated the rear of the sled and, after warming it up, opened the throttle to see what we could achieve rpm wise and whether or not it would throw a code. With no load, we could spin the motor up to 7600, no code thrown, and could watch the E-VES actuator move through the three positions.
When I removed the cable from the actuator, to do the service manual "push-pull" test for resistance and travel distance, the cable came out-- it was broken. This made me think about the E-VES system.
The system is set up where the ECU compares commanded position versus achieved position by comparing the hall effect sensor in the actuator versus voltage values at a given position. The problem with this system is that they are upstream of the actual exhaust valves and also the cable. Without a limiter switch on the actual exhaust valve or the tie-bar, there is no real way for the ECU to know if the intended valve position has been achieved.
There is a cable travel specification--full-in to full-out-- of 16-18mm.
If the cable has stretched, the exhaust valve may not fully open--leaving the exhaust port shrouded-- reducing peak rpm.
What can make this difficult to diagnose is that the ECU may not throw a code if the actuator hall effect sensor reaches it's intended position and the voltages correspond because they are upstream of the actual valves. This customer SKS did not throw a code and yet the cable was broken meaning the valves weren't opening at all.
How many Axys motors with low rpm issues have had the cable travel distance inspected? Are dealers doing this or are they simply using Digital Wrench to perform an E-VES re-learn without physically checking the travel distance?
I may add the cable to the list of components that I swap out at a specified interval (like motor rubber isolators) versus suffering cable stretch/ break performance issues.