high idle when warm outside

[SherKhan]

As the outside temperatures have been rising, my '04 GA has started having a high idle. usually around 1500 RPMs, but has had instances where the engine ran around 3k.
Doesn't matter if the engine starts out cold (not run that day) or after a drive.

I've checked the cruise control, air filter, throttle body, and can't see anything that would cause this.

I'm looking for ideas before I take it to the dealer.

thx

[Silver 4 door]

could be the Idie validation switch.

[rixGAphx]

could be the Idle validation switch.What's that?

[rixGAphx]

As the outside temperatures have been rising, my '04 GA has started having a high idle.
usually around 1500 RPMs, but has had instances where the engine ran around 3k.
Doesn't matter if the engine starts out cold (not run that day) or after a drive.

I've checked the cruise control, air filter, throttle body, and can't see anything that would cause this.What engine do you have: V6 or 4-cyl?
If 4-cyl, do you have an auto or manual tranny?

In either case, something is preventing the throttle plate from closing.
* Piece of grass or twig stuck in the throttle bore.
* Obstruction under the dash, preventing the throttle pedal from fully rising.
* Kink in one of the cables (throttle pedal or crusie control) to the 'bell crank' assembly that rotates the throttle shaft. Both of these cables MUST have a *little* slack at idle position; if either is tight, it's your problem.

The throttle plate must close fully at idle; air for idle goes around the plate via a passage, and the volume is controlled by the Idle Air Control (IAC) valve.
The computer operates the IAC very precisely to maintain proper idle, generally 600-900 depending on engine, temp, tranny, and load.
Under no circumstances can enough air flow thru the passage for 1500 rpm operation on either engine.

Hope this helps,
-Rick

[gt00]

What's that?It's beyond your limited scope of mechanical knowledge , very high tech stuff ..... :roll2:

[SherKhan]

rixGAphx - I checked the throttle cables and mechanical linkage on the outside of the throttle at the engine, and I checked the pedal and cables under the dash. Everything is clear of obstructions, the cables are not kinked, and move freely.
I haven't had a chance to pull the intake tube and check the plate itself for debris or damage. It's weird that it only seems to be occurring when the outside temp is above 60 degrees, or it is a remarkable coincidence.

The missus reported the RPMs hit 4k yesterday right after she started it to go home. I'm concerned that the constant torque will damage the transmission, or burn out the brakes.

I've made an appointment with a local dealer to have it checked. I will report back his findings.

[rixGAphx]

The missus reported the RPMs hit 4k yesterday right after she started it to go home.So, you *prolly* have an auto tranny.

WHICH ENGINE: 4-cyl or 6????
We can't picture the intake set-up in our minds, unless we know which engine you have.

The throttle was wide-open, and only the good sense of the computer prevented the engine from redlining and possibly blowing (the auto-tranny GA's are rev-limited in 'P' and 'N' to 4000 rpm; the manual tranny (only available with the 4-cyl) has no such rev-limiting)

I'm concerned that the constant torque will damage the transmission, or burn out the brakes.Actually, when the engine is running that fast, there is very little engine vacuum in the intake manifold.
And when you shift it into gear, you're right that there's a hell of a lot of torque.
But the real danger is that with the low vacuum, there is very little power-boost to the brakes.
The brakes won't 'burn-out' as such, but rather even a large adult male may have problems pressing the GA's (already-marginal) brakes hard enough to prevent the car from LEAPING forward into a pedestrian or garage wall or such.

Yeah, get this taken care of right away.