cjs27410

If my 03 sits for longer than 3 or 4 days it will rev up to 3000 or 4000 rpm
for maybe a second or two on initial start up. It settles to normal after the second or two. It makes no difference if the outside temp is cold or hot. If I drive it every day or two the start ups are normal with no rev ups. It's been doing this since new.
Anyone else experiencing the same?

cjs27410

Bill Curlee

The PCM controls throttle angle. When you turn the ignition to ON, the PCM should tell the TAC Module to position the throttle motor to go to the last known proper throttle blade IDLE ANGLE.

When you would normaly expect to see this high idle issue, remove the air ducting between the MAF and Throttle Body. Have someone turn the key to ON and watch the throttle blade. It should power up and errect and go to an idle angle. See what it does when you would expect it to rev up high when started.

Ahter it has its fit, see what the blade does when up first turn it on when it doesnt/ or wouldnt idle high.

You said its done this since new. What year C5 and why didnt the dealer fix it under warranty???

95wht6spd

Mine has been dong this after a tune, but only when cold. Cannot tell how high, since the needle sweeps on start up. Maybe only 2k...

78GEN3

Try to clean your throttle body. Could be hanging high after the car starts. I'm sure it needs cleaned anyway, can't hurt.