Alrighty so I took out my throttlebody and cleaned it this weekend. Simple Green, Brake cleaner its shiney again, moves freely and without a ton of effort.

So I reinstalled it, reconnected my intake 90* boot and plugged it back in. Restarted it and got a high idle....looks like about 1200 rpm instead of 800, but if I leave it sit there for about 45 seconds it'll slowly drop down to 800.

So I took the entire manifold out and cleaned it out as best I could tonight....reinstalled it, reconnected the vacuum line, the Manifold Absolute Pressure Sensor and the PCV valve. put the TB back on and reconnected it and it still has a high idle, although it did go down to 800 rpm in about 30 seconds instead of 45.

So here's where I sit....I'm thinking I'm going to replace the MAP sensor, and if that doesn't work, the MAF sensor, and if that doesn't work, I'll replace the vacuum line.......

Any ideas???


BTW my car has 30100 miles on it and the valves have a light coat of crap on them, and I cleaned the tubes that lead to the valves and they were cruddy and dirty.....oily from my breather lol not a whole lot of built up dirt....
AND PLEASE DO NOT TELL ME TO TAKE IT TO THE DEALERSHIP FOR WARRANTY WORK....I APPRECIATE THE LOGIC OF THAT SUGGESTION BUT NOT HAVING MY CAR FOR 3+ DAYS AT THE MOMENT ISN'T AN OPTION...

 

That sound like normal operation to me on a cold start.
Mine does the same thing.
Does it do it if you drive the car until it reaches operating temp, shut it off and start it again when the engine is hot ?

DTC P0507
Circuit Description
The throttle actuator control (TAC) motor is controlled by the powertrain control module (PCM). The DC motor located in the throttle body drives the throttle plate. In order to decrease idle speed, the PCM commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the PCM commands the throttle plate open allowing more air to pass the throttle plate. If the actual idle RPM does not match the desired idle RPM within a calibrated time, this DTC sets.

Conditions for Setting the DTC
• The actual idle speed is approximately 100 RPM greater than the desired idle speed.

• The above condition is present for 10 seconds


Inspect for the following conditions:

• Vacuum leaks

• Excessive deposits in the throttle body

• A faulty positive crankcase ventilation (PCV) valve

• A skewed manifold absolute pressure (MAP) sensor (I would think this means it not sitting straight in the intake)

 

No this is not just limited to a cold start (which i do agree is normal), however it is doing this anytime I'm stopped regardless of how long i've been driving. And to be honest...I have the repair manuals for my car as well, so I looked up that information too.

Well my DTC went away...but my idle still isn't right....BTW it does this everytime I stop, not just at a cold start....It'll be up at 1600 and then drop to 1100 and then sit there for about 8 seconds and then just drop to 800.....its weird....I rechecked/cleaned and sealed everything again and its still not right....I think its new MAP and PCV time.....

I have no vacuum leaks and my TB is spotless....(well almost :-P)

 

When you cleaned the throttle body ,maybe you stretched on of the springs that centers the throttle plate and its sitting a little skewed,I read it relearns its position everytime you start the car thats why it goes away when you are driving and the problem reappears when you start it,

Did you disassemble the throttle plate to get in and clean your throttle body ?

If not you probably stretched one of the springs getting in there to clean it.

 

I held it at WOT position while I cleaned it....I took the entire TB off the mani when I cleaned it....and when I say that I mean I disconnected the right side wiring....undid the 4 bolts that hold it and pulled it off and cleaned it and put it back on the mani....... no further disassembly happened....

I don't believe I stretched the springs since WOT is a lock point position and the TB flange will not open past that.....interesting prospect though...I'll look into it....

 

This is where I read it .

Throttle Body Assembly

The throttle assembly contains the following components:

• The throttle blade

• The throttle actuator motor

• The throttle position (TP) sensor 1 and 2

The throttle body functions similar to a conventional throttle body with the following exceptions:

• An electric motor opens and closes the throttle valve.

• The throttle blade is spring loaded in both directions and the default position is slightly open.

• There are 2 individual TP sensors within the throttle body assembly.

The TP sensors are used to determine the throttle plate angle. The TP sensors provide the powertrain control module (PCM) with a signal voltage proportional to throttle plate movement. The TP sensor 1 signal voltage at closed throttle is near the 5-volt reference and decreases as the throttle plate is opened. The TP sensor 2 signal voltage at closed throttle is near the low reference and increases as the throttle plate is opened.

Heres something else

Normal Mode

During the operation of the throttle actuator control (TAC) system, several modes or functions are considered normal. The following modes may be entered during normal operation:

• Minimum pedal value--At key-up the powertrain control module (PCM) updates the learned minimum pedal value.

• Minimum throttle position (TP) values--At key-up the PCM updates the learned minimum TP value. In order to learn the minimum TP value, the throttle blade is moved to the closed position.

• Ice break mode--If the throttle is not able to reach a predetermined minimum TP, the ice break mode is entered. During the ice break mode, the PCM commands the maximum pulse width several times to the throttle actuator motor in the closing direction.

• Battery saver mode--After a predetermined time without engine RPM, the PCM commands the battery saver mode. During the battery saver mode, the TAC module removes the voltage from the motor control circuits, which removes the current draw used to maintain the idle position and allows the throttle to return to the spring loaded default position.

 

thanks...I don't have my manual here at work so you putting this up helps me...

I would agree with your bent spring theory but there are 2 problems I run into with that.....
#1 the throttlebody has a max/min position set by a metal stop inside the tb....I don't think GM designed MAX/MIN points that could bend the springs...then again....it is GM....haha
#2 If I bent the springs my TB would not return to the minimum spring location like described above....

The way I see it, it is not the springs because my idle does return to 800rpm....if I did in fact bend the springs....it would make the idle permanently higher since the TB would not close as far as it did....

But because it is a good Idea i'll give it a shot this weekend.....see what it is...worse comes to worse I just buy a new TB...no big whoopiee...