Hi, I have a 3.0l ranger year 2006 with a cold idle that jumps up to 1800 rpm when putting transmission in drive. Idle is fine in park. It is dangerous because rear brakes are stressed to hold the truck and the front wheels might be on ice. This could cause running into the vehicle in front.

 

Welcome to FTE.

With the idle ok in P, or N, it Sounds like the IAC belongs on the suspect list. In case you may have more than one problem, use, borrow, or come by the inexpensive but powerful ELM scan tool & running FORScan diagnostic software on the viewing device of your choice as described here https://www.ford-trucks.com/forums/1...-scantool.html as it can access & query All of the vehicle computer / controllers for trouble code clues, then have it scan for trouble code clues & post All code Numbers, as they can help focus a trouble shoot.

If no code clues found, or you don't want to invest in that inexpensive but nifty scan tool, try disconnecting the IAC electrical connector, starting the engine & put it in gear & post up what happens.

If you come to suspect the IAC, you could remove it & try cleaning it internally with a plastic safe spray, like CRC MAF sensor spray cleaner. Keep the electrical connector end of the IAC elevated so the cleaner won't run into the solenoid end & possibly damage the winding insulation & cause the windings to short out & not work well, or at all..

After cleaning & letting it dry, reinstall, plug in its electrical connector & see if it makes any positive rpm difference. If it does, consider replacing the IAC with a Motorcraft, or BWD brand, as they have proven to be reliable. Cleaning the IAC might not last, it didn't for me but was a good trouble shooting step before replacing my IAC to cure my Ranger run away idle woes when coming to a stop.
On advice form FTE forum members, I chose a BWD brand replacement with a Advance discount promo code that made it cost attractive & its been fine for 10 years now.

Until you get the high idle fixed, keep the tranny in "N", until your ready to move out. Same when coming to a stop, just shift into "N" before stopping, is what I had to do when mine would suddenly act out & the RPM would run away. A couple of times it got high enough that it bumped the rpm limit, so the computer had to begin shutting off the fuel injectors to prevent a over rev.

A bunch of beginning thoughts for consideration, let us know how it goes.

 

HI, thanks for sharing your experiences with high idle. I omitted to emphasize this is this is only a problem during warm up. The idle speed in drive suddenly drops from very high to normal when warmed up. I don't know if that information would simplify or narrow down the possibilities.
I think colder weather makes it worse. We had one significant colder day and the idle was even higher but I can't confirm until winter hits some more.

 

Ok it not acting out after warming up is good feedback & a clue that I'm not certain just how to fit into the puzzle yet.

Without any trouble code clues to help focus a trouble shoot with an educated guess, right now I'd have to suppose maybe the IAC is mucked up a little with some deposits that soften up with warmer temps, so it stops hanging up after warming up, so if you don't have, or can't come by the ELM scan tool, to look deeper into all of the vehicle computers / controllers for stored, or pending trouble code clues, maybe consider removing & cleaning the IAC as outlined above & let us know how it goes.

EDIT: I suppose the same suspicions could be applied to the throttle plate OD. If deposits collect there it could cause the throttle plate to not seat fully & maybe cause enough air to bypass the plate that the IAC can't compensate because its beyond its designed range.

 

Hi, some changes to the high cold idle have happened. It has started to whistle loudly under cold acceleration and now I am getting codes P0171 and P0174. Warmed up the truck drives normally.

 

P0701 & 704 are auto & manual tranny codes, you can read about them here https://www.obd-codes.com/p0701 & here https://www.obd-codes.com/p0704, so you can see the two codes can cause confusion because the 701 is for an auto tranny & the 704 is for a manual tranny, so which tranny does this puppy have????

With the mileage on it, check the fluid level & condition, as your profile says 250,000 or more????, km I suppose, as your in CA & in a thread about the differential yoke, you indicated if this is the same vehicle, that it has 268,000 km, so is this still the same vehicle as last year???

If it has a manual tranny, check the rubber shift rail plugs to see if they are dry-rotted & leaking lube, if its leaking, time to drain the old fluid & replace the shift rail plugs.
If its auto tranny, check its fluid level & condition. If the fluid hasn't been changed in all those km's its likely in need of a pan drop, filter change & new full fluid pump-out, to get as much new fluid into the system as possible.

On the high idle problem last year, we need to know if it has a manual, or auto tranny & if we're talking about the same, or two different 06 3.0L vehicles????

 

I'm sorry I put the wrong codes in and then corrected it. The codes are P0171 and P0174.

 

Ok, thats good feedback clarification, P0171 & P0174 are generic lean both cylinder banks trouble code clues, so from the same site here are some ideas to check out & they may fit into your high idle problem too. https://www.obd-codes.com/p0171 & https://www.obd-codes.com/p0174. The PCV valve & its rubber plumbing parts belong on the suspect list, so inspect them closely as they're downstream of & not monitored by the MAF sensor, so if acting out can corrupt the air / fuel ratio to both cylinder banks.

Let us know if this puppy has a auto tranny & how the vacuum leak checks go.

 

I cleared the obd2 codes during this current warm fall weather. We will see if they come back when I get that loud whistle on cold acceleration that happens on colder mornings.
It is automatic transmission.

 

So on a cold morning (8 celcius) the whistling happened again and sure enough the engine light came back on with the same codes.
The whistle is only when the engine is cold and increases in pitch pressing more on the gas.
I am thinking these codes are benign and I should just ignore them.

 

Have you checked the upper & lower intake manifold fasteners torque, to see if any are loose??? Cold mornings will cause parts & gaskets to shrink, so if things aren't properly tight, they can shrink enough to have vacuum suck in air & seeing as how the upper & lower manifolds are down stream of & not monitored by the MAF sensor, vacuum leaks can cause a lean condition in both cylinder banks & if the leak is bad enough, it'll sound off. So have a helper rev the engine while you listen around the upper engine manifolds with a piece of rubber hose, one end to your ear & pass the loose end along the upper & lower manifold seal areas & see if you can locate the leak area & let us know what you find.

 

I did not need a helper, just cold started the engine and it was whistling. The decibles were extremely high causing ear pain at first. I had to stand back about 6 feet. Then it got a little quieter as the engine ran for a while. I listened with the hose but could not localize it to any part of the engine. It seems to be coming from underneath somewhere, not the top of the engine or the sides of the engine, perhaps from the front near the rad.

 

A leaking exhaust manifold, or down pipe can make a whistling sound that can vary with temp as things warm up & expand. If the leak is close enough to the upstream / before cat converter O2 sensors, it can corrupt their readings as the exhaust pulses suck in air at the leak & corrupt how much combustion O2 is really in the exhaust gas.

 

I am thinking not to fix something that's not actually broken. The truck runs fine warmed up and fuel consumption is ok. I was hoping there was some simple solution but better not touch it I guess.
Ocasionally it will drive itself when warmed up but I can live with it. On the highway I don't need to give it gas sometimes rarely, like a cruise control without the control.

 

Hold on, don't ignore something thats that loud & begging for attention. There may be a simple fix / solution, but you've not zeroed in on the noise area well enough yet. 'Close to the radiator" could be many things, from as mentioned intake or exhaust leak, noisy serp belt, to a serp belt driven component bearing, to a coolant hose, radiator, or radiator cap pressure leak, to....well you get the idea, the forum needs more detail to make a more informed guess. Maybe use your phone to post a picture & sound recording, as you walk around the vehicle with the hood up, while its noisy.