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Port engine described above with the 07 ECM has an erratic high idle that oscillates between 800-1200 RPM. Ii is rock steady at dead low idle (660 RPM) and above about 1200 RPM. This engine sat for 3 years without being run.
Rinda scan tool revealed no faults or error codes. The IAC valve stepper motor position was set a "0" and did not change during low idle when it was steady or high idle when it oscillated. Rinda Techmate Pro tool reported zero step position in both cases.
I'm thinking it is a stuck IAC valve unfortunately on this engine that part is integral with the throttle body and not replaceable (whole new throttle body assembly is needed). The engine also has a stumble going from low idle to higher rpms when the throttle is moved quickly.
Other possibilities are vacuum leak (but its steady at low idle) and throttle control position sensor. This engine has mechanical cables connected to an electronic throttle (TCP sensor).
The starboard engine runs steady at high and low idle and I am planning to connect the Rinda scan tool to that motor and see what values it reads back from the the IAC valve. Another option is two switch over the TCP sensor from starboard to port and see if that corrects the problem. The TCP sensor is relatively inexpensive the entire throttle body is not.
Would there be any gain removing the entire throttle body and cleaning it from the inside? The throttle body has a riveted plate (sealed) at the IAC Value location so you cannot access or remove the IAC Valve from the outside (picture attached).
Any advice appreciated the unstable high idle is a problem in close quarter maneuvering.
Port engine described above with the 07 ECM has an erratic high idle that oscillates between 800-1200 RPM. Ii is rock steady at dead low idle (660 RPM) and above about 1200 RPM. This engine sat for 3 years without being run.
Rinda scan tool revealed no faults or error codes. The IAC valve stepper motor position was set a "0" and did not change during low idle when it was steady or high idle when it oscillated. Rinda Techmate Pro tool reported zero step position in both cases.
I'm thinking it is a stuck IAC valve unfortunately on this engine that part is integral with the throttle body and not replaceable (whole new throttle body assembly is needed). The engine also has a stumble going from low idle to higher rpms when the throttle is moved quickly.
Other possibilities are vacuum leak (but its steady at low idle) and throttle control position sensor. This engine has mechanical cables connected to an electronic throttle (TCP sensor).
The starboard engine runs steady at high and low idle and I am planning to connect the Rinda scan tool to that motor and see what values it reads back from the the IAC valve. Another option is two switch over the TCP sensor from starboard to port and see if that corrects the problem. The TCP sensor is relatively inexpensive the entire throttle body is not.
Would there be any gain removing the entire throttle body and cleaning it from the inside? The throttle body has a riveted plate (sealed) at the IAC Value location so you cannot access or remove the IAC Valve from the outside (picture attached).
Any advice appreciated the unstable high idle is a problem in close quarter maneuvering.