low idle

[juniorinky]

I have a 2000 ranger. 4x4 with the v6 4.0.Love the truck but lately whenever I come to a stop the idle is low.Just low enough that I can feel it.I can touch the gas pedal and raise it where the engine feels better and the headlights get a touch brighter.Any way I can turn the throttle up just a hair on this?.Again I am talking just a hair to let it idle smoother.Also while im here im going to change the transmission fluid and filter I dont have the factory manual.How much fluid do I need and what type to drop the pan and change fluid and filter.Thanks.

 

[SenorNoob]

You should have an Idle Air Control valve. Sounds like it is stuck closed or has bad wiring. The computer should be using it keep the idle where it's supposed to be.

 

[bigtruck94]

It's either your IAVC or your idler pulley. How low are your RPM's?

 

[RonD]

Since fuel injected(EFI) engines don't have jets they all use an IAC valve, Idle Air Control to set idle level.
The computer, PCM, has a sensor on the crankshaft that tells it the RPM of the engine.
The PCM then opens or closes the IAC valve a bit to set idle at pre-set levels.
750 rpm when engine is warmed up
1,000 rpm when cold

When you start an EFI engine the RPMs should go up to 1,500+, then drop down to 1,000 or 750 depending on the engine temperature.
The high RPM is the PCM testing the IAC valve, opening it all the way, then closing it to set correct RPM.

Since the IAC valve is a mechanical device it can get dirty and stick a bit, but it can be removed and cleaned.
If you unplug the IAC valve connector, idle should drop to about 500-600 rpms

The MAF(mass air flow) sensor can also get dirty, this sensor tells the PCM how much air is coming into the intake and at what temperature, this sets the fuel/air mix.
This can also effect the idle somewhat and can cause bogging or stumbling, worth clean this as well.

 

[TrexMex]

Since fuel injected(EFI) engines don't have jets they all use an IAC valve, Idle Air Control to set idle level.
The computer, PCM, has a sensor on the crankshaft that tells it the RPM of the engine.
The PCM then opens or closes the IAC valve a bit to set idle at pre-set levels.
750 rpm when engine is warmed up
1,000 rpm when cold

When you start an EFI engine the RPMs should go up to 1,500+, then drop down to 1,000 or 750 depending on the engine temperature.
The high RPM is the PCM testing the IAC valve, opening it all the way, then closing it to set correct RPM.

Since the IAC valve is a mechanical device it can get dirty and stick a bit, but it can be removed and cleaned.
If you unplug the IAC valve connector, idle should drop to about 500-600 rpms

The MAF(mass air flow) sensor can also get dirty, this sensor tells the PCM how much air is coming into the intake and at what temperature, this sets the fuel/air mix.
This can also effect the idle somewhat and can cause bogging or stumbling, worth clean this as well.

¨
^^+1 .. Careful on what you use to clean the MAF sensor, though... Do not use carb cleaner or you will mess up the thin filaments used to measure the flow. Use only electronics safe fluids to perform the cleaning. I believe there's an article on the tech section on how to properly clean the MAF

 

[kryptonitecb]

Use MAF cleaner only when cleaning a MAF. It's a bit pricey but is still cheaper than replacing the sensor itself.

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