‘04 3.0 horrible idle

[StWeiler]

Against my better judgment I picked up an 04 Ranger with 3.0 for pretty cheap. It has a horrible idle (P0316) and spits n sputters from a drop. Once it gets past roughly 25 it runs fantastic. Supposedly has new coils/plugs/wires.
Any insight on where to start looking?

 

[1990RangerinSK]

My former house mate had a 4.0 Aerostar with a similar issue, except that it was fine as soon as it was off idle. I asked a local mechanic about it, and he said it was the idle control motor. There *should* be a thread about it somewhere here from last fall sometime.

I've also heard people here talk about automatic transmissions having a stall speed, and implying that a bad torque converter would cause an engine with an automatic to stall if the engine was below the stall speed. Maybe somebody who knows about that an chime in and explain it for us. Please?

 

[1990RangerinSK]

Here's the thread I mentioned above: http://www.therangerstation.com/forums/showthread.php?t=169279&highlight=idle+control+motor

Most of the thread is irrelevant to you, but one post *does* tell us how to determine whether the ICM is bad.

 

[adsm08]

I've also heard people here talk about automatic transmissions having a stall speed, and implying that a bad torque converter would cause an engine with an automatic to stall if the engine was below the stall speed.

That is not what "stall speed" means.

A torque converter's "stall speed" is the engine RPM at which the converter's normal internal function causes it to act like a physical coupler, rather than a fluid one.

To do a stall test you put the trans in gear, hold the brakes as hard as you can and start applying the gas. The "stall speed" is when the engine RPM where the torque converter's application of force overcomes the brakes ability to hold, because even though the TCC clutch isn't engaged the converter has effectively locked up or "stalled".

It has nothing to do with killing the engine.


Now a stuck torque converter clutch, staying engaged when it shouldn't can make the engine stall, but that is different terminology than what you were using there.

 

[StWeiler]

Is this something I should explore first? Or are there better routes to start with? IAC? O2 sensor? Vac leak? Intake gaskets?

Anyone with similar experience?

 

[adsm08]

Given your description the possibility of a stuck clutch certainly bears investigating.

The test is very simple, but requires some special equipment, namely a scanner that does transmission data.

You pull up the TCC slip actual and TCC slip expected PIDs and see if the numbers are close or not. I like to have engine RPM in there too. At idle in D the actual PID should be the same as engine RPM. If it starts going much lower than that something is keeping the converter clutch engaged. Then it is time to start looking inside the transmission.

 

[StWeiler]

I guess I wasn’t clear.
It doesn’t matter if it’s in park, or drive. The rough idle is there regardless. It seems like as it warms up the idle worsens and the sputtering from a stop light gets worse as well

 

[1990RangerinSK]

That is not what "stall speed" means.

A torque converter's "stall speed" is the engine RPM at which the converter's normal internal function causes it to act like a physical coupler, rather than a fluid one.

To do a stall test you put the trans in gear, hold the brakes as hard as you can and start applying the gas. The "stall speed" is when the engine RPM where the torque converter's application of force overcomes the brakes ability to hold, because even though the TCC clutch isn't engaged the converter has effectively locked up or "stalled".

It has nothing to do with killing the engine.


Now a stuck torque converter clutch, staying engaged when it shouldn't can make the engine stall, but that is different terminology than what you were using there.

Thanks. I learned something new.

 

[black_demon69]

I guess I wasn’t clear.
It doesn’t matter if it’s in park, or drive. The rough idle is there regardless. It seems like as it warms up the idle worsens and the sputtering from a stop light gets worse as well

Is the CEL on if so pull codes. Check for vacuum leaks clean map and throttle plate, check IAT. Check air filter also check fuel pressure.

 

[Jamesk09]

Pull and clean your IAC valve.

 

[Vackthcher]

Pull and clean Supplement reviews your IAC valve.

done and it's works

 

[helpme]

That's what mine was, when it did that. You should probably clean it when you prep for your emissions testing.
If you need a new one and they don't have it for the Ranger, the Taurus one will work but the connector comes off straight rather than at an angle.