Idling Low???

[alphabets13]

i had my idler pulley and serp belt replaced this weekend after the pulley fell off. right before it fell off i noticed that the truck was idling kinda low. around 500 at a stop. now i have the truck back and it still seems to be idling low.

when in park, it's at about 800, but when i shift gears it drops to about 500. any suggestions?

 

[JayTye4k]

Buy Seafoam from NAPA and run it through the intake, and also pour a can into your gas tank. This fixed my low idle.

 

[MrShorty]

Are those RPMS #'s based on the dash tach? Any other symptoms (loss of power, missing, coughing, sputtering)? In the absence of other symptoms, I could blame that on an inaccurate tachometer.

 

[Maniak]

On a cool morning, start the truck then disconnect the IAC. If the IAC isn't working the idle won't change. If it is, the idle will drop even more (and possibly stall).

The IAC's job is to lift the idle (its all called an air bypass valve in some books). Its near the throttle body, on the side of the intake (at least on the 4.0).

~Mark

 

[alphabets13]

On a cool morning, start the truck then disconnect the IAC. If the IAC isn't working the idle won't change. If it is, the idle will drop even more (and possibly stall).

The IAC's job is to lift the idle (its all called an air bypass valve in some books). Its near the throttle body, on the side of the intake (at least on the 4.0).

~Mark

i replaced that about 1 1/2 yrs ago. it was humming like crazy. i don't think that's it , but i'll check

 

[barnieman]

What is actually wrong with idling 500 in D/R/2/1 and 800 in P/N? My Explorer did that from the first day I bought it.

 

[Maniak]

The RPM itself may not be bad.. But if it didn't always idle that low, and now it doesn't that could mean an issue.. Especially when going by the factory tach.

BTW.. If you have lots of blowby or fill the oil while the motor is running you could foul the IAC in 1.5 years easily.

~Mark

 

[alphabets13]

well, it stalled today. i started it up, and after a few minutes i put it in reverse, backed up, put it in drive and bam, it stalls. the idle seems low compared to what it was before i had the idler pulley and serp belt replaced. it still feels like it did right before the idler pulley went.

the idle does seem to get better as the car warms up to normal temp, but never has it ever stalled before at all. something is not right. i want to sefoam it, and i will check the IAC valve, but i feel like it is something other than that. would the tensioner cause this?

my mechninc said i did not need a tensioner, that it was fine. shoulda had him replace it anyway.

any suggestions?

 

[Maniak]

You can check the tensioner yourself, but I doubt it is bad enough to make it stall even if it was bad. It would make the belt squeel etc but the belt isn't "locked" onto the tensioner, it just sliders over it so even if it was bad, the belt would move, but the tensioner wouldn't move and it would be loud and stink and problably smoke, but it wouldn't stall the motor..

If you do want to check it, just loosen the tensioner, and remove teh belt from under the tensioner. Then spin the tensioner..

~Mark

 

[alphabets13]

You can check the tensioner yourself, but I doubt it is bad enough to make it stall even if it was bad. It would make the belt squeel etc but the belt isn't "locked" onto the tensioner, it just sliders over it so even if it was bad, the belt would move, but the tensioner wouldn't move and it would be loud and stink and problably smoke, but it wouldn't stall the motor..

If you do want to check it, just loosen the tensioner, and remove teh belt from under the tensioner. Then spin the tensioner..

~Mark

thats probably definitely not it then. since i told my mechanic to replace it if it needed to be and he said it was fine. i'm sure he would have it he thought it needed it.

any other suggestions?

 

[alphabets13]

maniak, i know you said to check the IAC valve, i'm going to do that today, but what did you mean when you said that "blowby" could cause it do go so quick. i never fill the oil while it's running so i know that it is not that.

is the blowby caused by something that maybe needs to be cleaned? thanks for the help. hopefully it's just the IAC valve, thats an easy and fairly inexpensive fix.

 

[briwayjones]

If it's the IAC valve again before you replace it you can try cleaning it so you don't have to buy a new one.

 

[alphabets13]

If it's the IAC valve again before you replace it you can try cleaning it so you don't have to buy a new one.

yes, i will definitely do that first. thanks.

 

[WillieTD]

It could also be the TPS (Throttle Position Sensor). I had a rough idle until I replaced mine. And don't mess with that ridiculous "TPS mod" (if you don't know what I mean, do a search). It's a complete waste of time, not to mention you can get a new TPS for about $30.