2004 Ford Ranger XLT erratic idle

[Sdsmracer95]

Hello,
So i just replaced a bad Idle Control Valve since i got a check engine light.
so after replacing it with a new one from 0'reillys i started getting a high idle. then it drops suddenly. at momments it goes up again to around 1500rpm-1700rpm. and if drop it in neutral it goes up to 3200rpm and nearly hitting the free rev limiter.

got a new one from oreilly and it still did it. i have Zero vacuum leaks.
so im trying to see what can be done with this.

do i have to flash the ecu so it re-learns the new ICV? i know its had the ECU flashed since its had the speedo corrected.
ive tried disconnecting the battery and it still does it. so im very lost. could it just be the fact that its an oreilly part? any suggestions?

 

[Rearanger]

Start from fresh and erase ECU memory by pulling its fuse for 5+ minutes or disconnecting battery negative.

What happens when you disconnect IAC electrical connector when on idle?

 

[Sdsmracer95]

Start from fresh and erase ECU memory by pulling its fuse for 5+ minutes or disconnecting battery negative.

What happens when you disconnect IAC electrical connector when on idle?

ive tried that. i disconnected the battery for about 15min.
when i disconnect the IAC the rpm drops to about 600-650 rpm.it idles fine

 

[Rearanger]

What code did you get with the CEL? Does it do this hot or cold engine?

If your IAC is like mine it does not close completely, so you will get idle when disconnected.

 

[Sdsmracer95]

i got p0511 i think.
and this is the second one. like itll work for a bit then bump the RPM up and it idles super high. and then itll drop it down. people stare at me lol...

 

[Rearanger]

I'd look at the engine coolant temp sensor to see if your getting cold signals from it, that will increase idle.

I also wonder if that speedo re-flash might have done something. On my engine as I coast the idle stays high in relation to the speed.

 

[Sdsmracer95]

Well my temp gauge isnt moving.
so i doubt its that. its just annoying that its not idling fine. it waste gas -_-

 

[Rearanger]

Well my temp gauge isnt moving.
so i doubt its that.

The ECT is not your temp gauge sender, that's separate. There are two engine coolant sender/sensor, one for gauge (one wire) and one for the ECU (two wire).

The ECT tells the computer engine temp so it can vary fuel trim and engine RPM. That's why on cold startup your rpm is higher. If it is sending information that your engine is cold when it's hot them it could account for the high rpm. It will also cause poor gas mileage.

 

[enjr44]

Don't change the temp sensor until you have tested it. The how to is here on the forum, easy to do with a volt meter. They do fail; but, not often. And I am talking about the sensor, not the sender. You also may have a sender that runs the gauge, I don't know what year ford dropped the sender and had the ECU run the gauge.

You said you changed the IAC valve. Why? Next Q, did you test the old one or just change it. Finally, new parts no longer get tested before being sold. YOU get to do the "did we build it right" testing.

So, when you change a part and you get a different fail, my first guess now a days, is I got a bad part. Take it back and get another one. The stores get to many bad parts back they don't even blink.

Another thing to check is the wiring to the valve. Could you have a messed up connector or wire. If the connection is intermittent I would guess the idle would be all over the place.

One more thing to consider. I have been told that there is a big difference between the Motorcraft valves and "the others". A Motorcraft valve is about 70 bucks @ Rockauto and their cheap one is about 30. Got to be some reason why.

 

[Sdsmracer95]

well gentleman.

I went to my local junkyard got a Ford OEM ICV and it fixed it. it was a crappy oreilly part -_-.

all this headache and it was just that. im returning the part to get my money back

Thanks for all of your input guys.

 

[enjr44]

Thanks for the followup and glad you got it fixed, Ed