Truck accellerates without throttle input
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Truck accelerates without throttle input
When I start the truck it immediately revs up to 2k and starts climbing, when I put it in drive it drops to about 1500 and when I let my foot off the brake it starts accelerating. The acceleration isn’t fast my any means and I can still drive the truck but it is much faster than it should be. When it gets to operating temperature the problem completely stops and drives regularly.
Last edited by ConnorB3000; Aug 6, 2021 at 08:50 AM. Reason: Misspelled words
Welcome to the forum
What YEAR 3.0l Ranger?
On cold start any gasoline engine needs to be Choked, that means Rich Fuel mix and high idle, high idle should be about 1,100rpm, then drop to 800rpm after 4 to 5 minutes of warm up
There are 3 devices used for the Choke
ECT(engine coolant temp) sensor, 5volt 2 wire sensor, it tells computer if engine is cold or warm, NO connection to Dash Temp Gauge
Computer, it gets the temp from ECT and sets the Idle Level
IAC Valve, 12volt 2 wire solenoid that lets in air to set idle RPMs, controlled by the computer
If ECT should report temp as -40deg then idle could be 1,500+
So faulty ECT sensor can cause the high idle, and as it warms up it shows correct 185deg after 4 to 5 min, so idle drops to "normal" levels
IAC Valve can get dirty and stick open
When you turn on the key the computer boots up and OPENS IAC valve all the way for start up
After start up computer closes IAC Valve to set idle RPMs according to temp from ECT
Stuck open IAC Valve can certainly hit 2,000+ RPMs
Then after things warm up it loosens up and closes to set proper idle
How to clean IAC Valve seen here: https://www.explorerforum.com/forums...-w-pics.84220/
Just on speculation I would clean IAC Valve first, its free
Then look at replacing ECT Sensor if cleaning doesn't help
ECT sensor is for computer use only, 5 volt 2 wire, grey/red wire
There is a similar looking device on the engine for the dash temp gauge, its a 12 volt temp SENDER, usually has just one red/white wire attached, no connection to idle or computer, its just an info device for driver to see engine temp
What YEAR 3.0l Ranger?
On cold start any gasoline engine needs to be Choked, that means Rich Fuel mix and high idle, high idle should be about 1,100rpm, then drop to 800rpm after 4 to 5 minutes of warm up
There are 3 devices used for the Choke
ECT(engine coolant temp) sensor, 5volt 2 wire sensor, it tells computer if engine is cold or warm, NO connection to Dash Temp Gauge
Computer, it gets the temp from ECT and sets the Idle Level
IAC Valve, 12volt 2 wire solenoid that lets in air to set idle RPMs, controlled by the computer
If ECT should report temp as -40deg then idle could be 1,500+
So faulty ECT sensor can cause the high idle, and as it warms up it shows correct 185deg after 4 to 5 min, so idle drops to "normal" levels
IAC Valve can get dirty and stick open
When you turn on the key the computer boots up and OPENS IAC valve all the way for start up
After start up computer closes IAC Valve to set idle RPMs according to temp from ECT
Stuck open IAC Valve can certainly hit 2,000+ RPMs
Then after things warm up it loosens up and closes to set proper idle
How to clean IAC Valve seen here: https://www.explorerforum.com/forums...-w-pics.84220/
Just on speculation I would clean IAC Valve first, its free
Then look at replacing ECT Sensor if cleaning doesn't help
ECT sensor is for computer use only, 5 volt 2 wire, grey/red wire
There is a similar looking device on the engine for the dash temp gauge, its a 12 volt temp SENDER, usually has just one red/white wire attached, no connection to idle or computer, its just an info device for driver to see engine temp
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