2008 Ranger XL high idle in neutral


Fromthedeep55

New member
Joined
Jun 1, 2019
Messages
2
Reaction score
0
Points
1
Location
Lousiana
Vehicle Year
2008
Make / Model
Ford Ranger XL
Transmission
Manual
I have a 2008 Ranger XL with the 2.3 L four cylinder engine and 5 speed manual transmission. I just upgraded my air filter for a K&N and cleaned my MAF sensor, throttle body, and IAC valve at the same time. Once I got everything back together and took it for a drive everything seemed good, no check engine light showing, but when I coast to a stop in neutral the engine stays at 2000 RPMs until the truck is at a complete stop and then drops off to around 750 RPMs which is about what it normally is. It idles smoothly at a stop, but the high idle while driving is killing my fuel economy.

After doing some other research trying to correct the problem I've tried replacing the IAC valve, the MAF sensor, cleaning the contacts in all of the electrical connectors with contact cleaner, resetting the PCM by disconnecting the negative battery terminal for 20 minutes a couple of times, and testing the TPS with a multi-meter which sweeps smoothly from 1 volt fully closed to 4 volts fully open.

Any help on where to go from here would be greatly appreciated.
 


Rock Auto 5% Discount Code: 248EE46702D889 Expires: October 1, 2019

Uncle Gump

Well-known member
Supporting Member
Joined
Sep 17, 2018
Messages
1,127
Reaction score
388
Points
83
Location
Plano IL
Vehicle Year
2006
Make / Model
Ford
Engine Size
4.0L
Transmission
Automatic
2WD / 4WD
4WD
My credo
Lead, Follow or get out of my way
This only happened after you fooled with it?
 

Bill

Active member
Joined
Aug 6, 2007
Messages
307
Reaction score
31
Points
28
Location
Sacramento, CA
Vehicle Year
2007
Make / Model
Ford Ranger
Engine Type
2.3 (4 Cylinder)
Transmission
Manual
2WD / 4WD
2WD
" I coast to a stop in neutral the engine stays at 2000 RPMs until the truck is at a complete stop and then drops off to around 750 RPMs which is about what it normally is. It idles smoothly at a stop..."
If this occurred with the original IAC valve, it was good. Actually, this is a good way to test an IAC valve. Under normal circumstances, your idle will be a little high (mine is around 1200 to 1500) until you come to a complete stop, at which point the speed sensor tells the PCM the vehicle has stopped. The PCM then signals the IAC to reduce idle. The higher idles while the vehicle is moving eases shifting and improves emissions. Another way to test an IAC for correct operation is to observe the idle on a cold startup. Idle should start out high and gradually decrease in a series of steps as the engine warms. Note that this isn't going to catch one that is sticking randomly, but if your idle adjusts itself under these conditions chances are your IAC is OK.

Back to the higher idle, if you want to check and see if everything is working as it should you can always put the stock air cleaner and filter back on. If everything operates normally you know it is the K&N air filter. If not, then make sure you have all the vacuum lines connected. There is one that goes from the original air snorkel to the right side (passenger side) of the manifold. I've missed that one a few times when I've been working on things, although I'm inclined to think that would be a large enough leak that the IAC couldn't correct, in which case it would throw a code, which would likely be a code pertaining to the IAC, meaning the IAC doesn't have the ability to correct the idle (IAC related codes don't necessarily mean the IAC is bad).

Other possibilities I've experienced: I had an experience wherein the idle remained excessively high between shifts (manual transmission). The problem was that the throttle position sensor was worn and sending a voltage to the PCM indicating the throttle was open wider than it was between shifts. I think this led the PCM to signal the IAC to maintain a high idle between shifts instead of dropping it to a reasonable RPM range to ease shifting. In another case, I changed the air filter underneath a tree that drops leaves, seeds, twigs, etc, and some of the debris landed in the airbox and was sucked in the intake snorkel weeks later. The first high idle incident was from a leave that wedged itself on the outer perimeter of the throttle plate, keeping it slightly open and raising the idle. One I removed the leaf everything was fine until a seed managed to find its way into the IAC and prevent the valve in the IAC from closing. I removed the seed, reinstalled the IAC, and this time I vacuumed the airbox and made sure there wasn't any more crap that could get sucked in the manifold.
 

johnwfarquhar

New member
Joined
Jun 13, 2019
Messages
4
Reaction score
0
Points
1
Location
Pearland, Texas
Vehicle Year
2008
Make / Model
Mazda B2300
Transmission
Manual
I have the exact same thing happening on my 2008 B2300 for the last 2 days! I also have the Duratec 2300 and 5 speed stick. I've had a k&n in the stock airbox fo 2 years without issues, that's not the problem. Two days ago, I decided to clean my maf sensor with crc maf cleaner for the first time in 163k miles. It was definitely dirty, now it's clean,,, the truck ran fine after the cleaning. Then I got the bright be idea to check my throttle body and iac valve. Throttle body was very dirty as was iac. I removed the throttle body and iac from it and cleaned them both with crc throttle body cleaner. Put it back together and NOW I have a problem. It idles fine when not moving, but if the truck is moving, in neutral, the idle remains at 2200 until you come to a stop. It begins to drop a little as you slow to 5mph and then drops to 850 or so, moments after coming to a full stop. I installed a new iac valve but there was no improvement. I also tried removing the negative battery terminal and shorting between the disconnected negative cable and the connected positive cable for 15 minutes to clear the pcm. Then I reconnected everything and with a cold engine, started up and let the engine idle in the driveway for an hour,,, then went for a drive. Same problem! Help!
 

johnwfarquhar

New member
Joined
Jun 13, 2019
Messages
4
Reaction score
0
Points
1
Location
Pearland, Texas
Vehicle Year
2008
Make / Model
Mazda B2300
Transmission
Manual
Solution!!!
I finally found the answer to this problem! I ordered a new throttle body from Ford, put it on and it's FIXED!!!
This was driving me nuts for weeks. In 2 posts, I read that Ford Ranger throttle bodies have a teflon coating on the edges of the butterfly and where it almost touches the inside of the throttle body. This is to make a seal when the throttle is closed, without allowing the throttle to stick in the closed position. This forces idle air to be handled by the IAC valve.
My old throttle body (which was working fine) had a thick black coating making the teflon coating underneath just look like more carbon buildup. I cleaned it thoroughly with CRC and ruined it!
When I got the new throttle body from Ford, I could see this coating on the edges of the butterfly and inside the throttle body where the butterfly touches the inside of the body. IT DOESN'T LOOK LIKE IT BELONGS THERE,,, BUT IT DOES!!! IT'S UGLY AND LOOKS WRONG BUT IT'S NOT!
I bought a new one from an online discount Ford dealer delivered with a new throttle position sensor installed for $73.00 delivered! Do it.
 

Dirtman

Well-known member
EMT / Paramedic
Joined
May 28, 2018
Messages
2,384
Reaction score
715
Points
113
Location
Over there --->
Vehicle Year
2009
Make / Model
Ford
Engine Type
2.3 (4 Cylinder)
Engine Size
466.63 teaspoons.
Transmission
Automatic
2WD / 4WD
2WD
Tire Size
So friggin big!
My credo
Give me money.
Glad you got it fixed. FYI crc makes "coating safe" throttle body cleaner. In the future make you use that and only a very soft bristled toothbrush or microfiber cloth to clean it. Also even though it's a nightmare, change you pcv valve regularly and it'll cut down on amount of gunk that ends up in the throttle body.
 

johnwfarquhar

New member
Joined
Jun 13, 2019
Messages
4
Reaction score
0
Points
1
Location
Pearland, Texas
Vehicle Year
2008
Make / Model
Mazda B2300
Transmission
Manual
I've never touched the PCV... Hmmm. Along with my B2300, I just bought a 2006 Ranger Duratec 2300 so I need to get better at this... Thanks
 

johnwfarquhar

New member
Joined
Jun 13, 2019
Messages
4
Reaction score
0
Points
1
Location
Pearland, Texas
Vehicle Year
2008
Make / Model
Mazda B2300
Transmission
Manual
Even after all these changes and ending up with the new throttle body from Ford, it still had a rolling idle of 1500,,, way better than the 2200 from when I over cleaned the original throttle body, but not what I had before. This is with the O'Reilly idle air control on it. I went back to the original Ford one and it's around 1100 rolling idle now!
Moral is: Use Ford Parts!
 


Top