It's me said:
Hi Jeff,
Exact same problem here on a 2002 Elantra with manual transmission.
I changed the throttle position sensor with no help.
I can normally avoid the engine revving to high by quickly releasing the
clutch just after startup (I always startup the engine in neutral). My
theory is that the engine is having an extra load when the clutch is
released. This extra load slows down a little bit the rpm and, for some
reasons, the computer will finally realize this is idle condition.
It seems to me that you guys are complaining about the normal operation
of the engine. Mine will spike to ~2500 rpm during a cold start, but it
drops down immediately. Unless yours stays at high RPMs for an extended
time, there's nothing wrong with it.
By the way, I also find another "anomaly" which is maybe related to
overrevving at startup: when changing gears from 1st to 2nd or from 2nd to
3rd, the engine drops rpm slowly when warm. Does not happen when changing
from 3rd to 4th or 4th to 5th or when the engine is warming up or when the
engine is loaded with AC or rear defroster.
It's not an anomaly; it's designed that way. This is the throttle
"hover" that enthusiast drivers are constantly complaining about. It
does it in all gears and is actually dependent on RPMs, not the gear
itself. I haven't heard a concrete explanation of whether it's an
emissions reduction method or simply an adjunct to the equally annoying
clutch valve to make stalling less likely in the case of a bad shift,
but it's frustrating to an experienced manual transmission driver, as it
make rev matching more difficult.