Idle Air Volume Learning not saving

[rhorton1]

Long time reader first time poster here...

I have a 2003 Pathfinder SE 4x4, Automatic Transmission

I made the mistake of moving the throttle body butterfly valve while cleaning it, and have had high idle problems ever since (Code P0507). The car will idle between 1100rpm and 1500rpm after startup, depending on temperature. I've gone through a lot of troubleshooting, and just can't get the problem fixed.

So far I have done...

ECU Reset
Accelerator Pedal Released Position learning
Throttle Valve Closed Position learning
Idle Air Volume learning
(All of the above done multiple times)

When I do the reset procedures, the idle will drop to just over 750rpm (perfect!), but once I turn the car off for a while (a few minutes to a few hours) the high idle problem will return with the next start up.

I was told that I likely damaged the sensitive electrics inside the throttle body, and installed its replacement today. However, after completing all of the above procedures (with the car properly warmed up), the high idle problem still comes back after shutting the car down. Its the same as before... Do the procedures to learn proper idle, and the idle is right on the money until I shut the car down. At the next start up the idle RPM pops up to over 1000rpm.

Is there a step that I'm missing? How do I get the Idle Air Volume learning procedure to "stick" and save in the system so that the high idle problem doesn't come back with each start up? Thanks in advance for the help!

[Buzzman]

I made the mistake of moving the throttle body butterfly valve while cleaning it, and have had high idle problems ever since (Code P0507).

I believe your problem is right there. I'm 95% sure it's a mechanical problem.
Having gone through this whole no idle, high idle, IACV, ECM rebuild crap, I have a pretty good idea of how it all works.
The main throttle body valve has to be absolutely and completely shut tight when your foot is off the gas.
If it is open even a tiny bit, then the engine is getting too much air, and the idle goes up.
The only air that the engine requires at idle is metered through the IACV.
The IACV opens up ever so slightly, and lets in a little air through the bypass in the throttle body, giving it just enough air to idle at 750RPM's.
If your main butterfly valve is not seated properly, then no matter what you do to the electronics, or how many times you do the idle relearn, it will not idle properly.
Start by double and triple checking that valve to make sure it is seated properly and tight.

[rhorton1]

Thanks for the info. When I installed the new TB (an new Hitachi TB), I held it up to a light to make sure the butterfly valve was seated properly. Everything looked good, with the valve firmly seated against the TB housing, so I installed the new TB with a new TB gasket.

During my troubleshooting this morning, intrigued by your comment Buzzman, I discovered that the new TB now doesn't seat properly!! There is now about 2 or 3 mm of travel from the "rest" position that the TB is in when the car is off to the fully closed position. Any idea on what would be causing this? I figure that it has to be something in the car's computer that is telling the TB valve to be in the wrong position. Any thoughts would be appreciated!

[Buzzman]

Sounds like you found your idling problem. Now all you have to do is figure out how to fix it.

Now, I'm not sure on this, so you'll have to enlighten me, but I believe the throttle linkage system changed from 2002 to 2003.
On my '02 Pathy, the gas pedal is directly linked via cable (1950's technology) to the throttle valve.
In my case all I have to do is move two nuts back and forth to get the right adjustment in the cable. Dead simple and easy.
My understanding is that the 2003 design is more of a fly by wire system. Is this correct?
If it is, then you'll have to refer to the FSM on how to adjust it 'cause I won't know.
Maybe someone else on here with a 2003 or 2004 vintage truck can help with this issue.