A few weeks ago I noticed that my idle rpm's were going up and down a bit. The bike ran ok, but when going home from a trip the engine was not working properly under 4000rpm.
My first thought was that the TPS was acting up, so I put it in dealer mode and the C00 line would jump up around 3000rpm.
I also found out that the breather filter in the airbox was almost gone.
Cleaned out the airbox, put in a new air filter and still waiting for the breather filter.
Changed the TPS, sync'd the throttle body's, but the idle was still inconsistent. It starts when the engine is hot, 3 temperature bars.
The wierd thing is when I unplug the vacuum tube from the air pressure sensor the idle rpm's are then consistent and dead steady.
There are no vacuum leaks, new vacuum hose and caps.
There is nothing blocking the vacuum tube either (checked it).
Not getting a C13 error code.
The secondary throttle plates have been out for 10 years.
It looks like that for some reason the STA motor starts moving up and down trying to compensate for something and in the process also moves the primary throttle plates.
The idle speed has been inconsistent in the past as well when the engine gets hot, like driving through heavy traffic in a hot day.
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