Idle Problems...help please

[Rembrandt]

Well my friend has a 2000 Ford Ranger. 2.5L. We are having a pretty big idle problem with the truck and can't seem to figure out what it is. When you rev the engine or say the RPMs are up when driving and let off/put in the clutch whatever, just for it to idle back down everytime it holds whatever RPM it was at for anywhere from 5-10 seconds. before it slowly creaps back down to normal.

not throwing any codes of any kind. even just tried scanning the Cpu to see if something was hidden. We did routine maintenance cuz it was needed (plugs, wires, coil packs). Then my truck recently slung a rod (98 model, same engine) and I had recently changed the TPS (Throttle Position Sensor) and the IAC Valve (Idle Air Control). So we put them on his truck since they were fairly new to see if any change would happen. No change nothing. Everything was still the same.

Any ideas what the problem might be? We are completely baffled

 

[marc11]

It is normal. You'll notice it is speed dep too. If you are coasting with the clutch in the idle will hold for as long as you coast. Once you come to a stop it will drop down. Also, if you let off the gas and keep the clutch out the RPM will drop with engine speed, the computer is not holding the idle up while driving, just between shifts/when the clutch is in while the truck is moving.

Lots of topics on it. Not sure why this is set up this way, but I suspect it is to make smoother shifts and or reduce the truck jerking/bucking when a noob takes so long to shift the RPM's drop too fast.

 

[PaleBlue90]

ive never heard of that

 

[Rembrandt]

Well they have had the truck for about 2 years now. I've drove it numerous times. It has never done it before until the past 3-4 months.

I've never heard of that being normal either, kinda weird if it really is

 

[marc11]

Search this site for hanging RPM or hanging idle or search the net. There are tons of discussions on this topic. I've had my truck for three months and JUST NOW noticed it this week, did a search and boom, lots of talk on it. It is normal.


Read this and follow the links within the thread too:

http://www.therangerstation.com/forums/showthread.php?t=12605

 

[Rembrandt]

Thanks alot Marc. That link helped alot. Kinda dumb how that is a normal problem. We might experiment with some restrictor plates like many people are saying fixes the problem.