Engine will idle but will not accelerate - Honda Cars & Trucks

1. Worn clutch: If the clutch is worn, it may not be disengaging properly when you change gears, causing the engine to continue to rev as if you were still accelerating. This can also cause difficulty shifting gears or a slipping feeling when accelerating.
2. Dirty or faulty throttle body: The throttle body controls the amount of air entering the engine and adjusts the idle speed. If it's dirty or faulty, it may not be closing properly after you release the accelerator pedal, causing the engine to continue to rev.
3. Vacuum leak: A vacuum leak can cause the engine to rev excessively or idle roughly. The leak can be caused by a cracked or disconnected vacuum hose, or a malfunctioning intake manifold gasket.
4. Faulty idle air control valve: The idle air control valve regulates the engine's idle speed. If it's faulty, it may not be closing properly after you release the accelerator pedal, causing the engine to continue to rev.

Your Denali has Throttle Actuator Control (TAC) System - Electronic throttle control ! Are there any messages on the driver information center ? Reduced engine power ?
Reduced Engine Power Mode When the PCM detects a condition with the TAC system the PCM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions:
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Acceleration limiting--The control module will continue to use the accelerator pedal for throttle control; however, the vehicle acceleration is limited.

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Limited throttle mode--The control module will continue to use the accelerator pedal for throttle control; however, the maximum throttle opening is limited.

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Throttle default mode--The control module will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.

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Forced idle mode--The control module will perform the following actions:

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Limit engine speed to idle by positioning throttle position, or by controlling fuel and spark if throttle is turned off.

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Ignore accelerator pedal input.

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Engine shutdown mode--The control module will disable fuel and de-energize the throttle actuator.

You need to have it checked for DTC'S - diagnostic trouble codes , probably a accelerator pedal position (APP) sensor or TPS - throttle position sensor !

it is a possibility the potension meter does not working. It is on the accelerator pedal,by using a scanner surely you will get the correct fault.

has base idle speed and kurb idle speed. allows engine to close throttle opening when shutting down to stop pre-ignition or engine running on

what car is it? your car using carb or fuel injection

Its a vacuum issue.The vacuum hose or line is cracked and there is a vacuum leak.Click the link below and see the troubleshooting for this problem:----http://technoanswers.blogspot.in/2012/02/engine-accelerates-when-brake-is.html
---------This will help.Thanks.

No to both questions. The idle valve is only for idle control, letting in more or less air as idle conditions warrant, to keep engine at proper idle RPM. The old choke would reduce air supply on a cold engine to allow starting with a richer gas mixture. That function is taken over by the computer in injected cars by allowing longer injector pulses to give richer mixtures in cold engines. Once warm, the 02 sensor controls fuel trim through the computer.
By "accelerating itself", do you mean your idle is higher now that it's colder outside? I suppose it's possible if the idle valve is out of calibration, it might cause that. It is computer controlled, so proper diagnosis of the idle control valve requires a multimeter. The throttle position sensor should also be looked at for a high idle. Good luck.

run the fault codes
indicates an idle control sensor or other throttle / accelerator sensors

no, idle air control valve is literally to control your idle speed.
what happen when you press on gas? car shakes, RPM goes up, or engine just bogs down?

the idle controls could be the problem