A couple nights ago I was fiddling with my G35 5AT. There were times where I was depressing the throttle while the ignition was on, but the motor was off. Apparently while screwing around, I must have inadvertently performed the Accelerator Pedal Release Postion Learning or the Throttle Valve Closed Position Learning procedures. The yesterday morning I started the car and everything seemed normal. As I continued to drive, I could feel the tranny down****ing every gear as I came to a stop. This resulted in slight surges as the brakes were applied as speeds dropped below 5mph. Most people wouldn't have noticed it, but I did. I figured the issue was caused by the colder temps were experiencing in Kansas City and the ECU was adjusting it's idle. I also noticed that the idle seemed a bit higher than normal indicating about 800rpms instead of about 600rpms. Again, I figured it was due to the cold weather. Last night while driving to my volleyball game, the check engine light appeared. When I got home I plugged my car into my laptop and pulled the CEL. It was P0507 which is the code for "engine idle higher than expected". The OBD logger indicated that my warm idle was at 780-800rpms which is above the target warm idle of 650+/-rpms.

Since the CEL appeared one day after me fiddling with the car and I had noticed the surge and high idle, I figured the problem was caused by me. I opened my FSM and it said that the code may indicate a vacuum leak, a faulty ECU, or a throttle issue. I went with #3, though I did check vacuum and it was fine. As I read the throttle learn procedures, it appeared that I may have performed one of the procedures. Since the idle was the issue, I performed the Idle Air Volume Learning procedure. After performing the procedure, the idle dropped to 630-650rpms. Perfect I thought. Then I drove around and the idle started to raise back up to 800rpms. I'd restart the car and it was the same thing. The idle was too high. A couple minutes later the CEL came back on. SOB! I then read the Idle Air Volume Learning procedure and it said you need to first perform the Accelerator Pedal Release Postion Learning and the Throttle Valve Closed Position Learning procedures. I guess it helps if you read the directions right the first time. I performed all three procedures and then started the car. The idle was correct and I drove around for 30 minutes and did about 5 restarts. The idle stayed in the indicated 600-650rpm range. This morning, the idle was perfect. Additionally, after getting the idle set right, the gear surging was gone which makes sense since the idle is lower. The CEL has not come on since.

So, if you ever get a P0507 code and you had been fiddling with your car shortly before, you may have done a throttle learn procedure. I've listed the procedures below.


Accelerator Pedal Released Position Learning

OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch “ON” and wait at least 2 seconds.
3. Turn ignition switch “OFF” wait at least 10 seconds.
4. Turn ignition switch “ON” and wait at least 2 seconds.
5. Turn ignition switch “OFF” wait at least 10 seconds.


Throttle Valve Closed Position Learning

OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch “ON”.
3. Turn ignition switch “OFF” wait at least 10 seconds.
Make sure that throttle valve moves during above 10 seconds by confirming the operating sound.


Idle Air Volume Learning

PREPARATION
Before performing “Idle Air Volume Learning”, make sure that all of the following conditions are satisfied.
Learning will be cancelled if any of the following conditions are missed for even a moment.

Battery voltage: More than 12.9V (At idle)

Engine coolant temperature: 70 - 100°C (158 - 212°F)

PNP switch: ON

Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime light systems, set lighting switch to the 1st position to light
only small lamps.

Steering wheel: Neutral (Straight-ahead position)

Vehicle speed: Stopped

Transmission: Warmed-up
For A/T models with CONSULT-II, drive vehicle until “FLUID TEMP SE” in “DATA MONITOR” mode of “A/
T” system indicates less than 0.9V.
For A/T models without CONSULT-II and M/T models, drive vehicle for 10 minutes.

OPERATION PROCEDURE

NOTE:

It is better to count the time accurately with a clock.

It is impossible to switch the diagnostic mode when an accelerator pedal position sensor circuit
has a malfunction.
1. Perform "Accelerator Pedal Released Position Learning" .
2. Perform "Throttle Valve Closed Position Learning" .
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic “PRE-CONDITIONING” (previously mentioned) are in good order.
5. Turn ignition switch “OFF” and wait at least 10 seconds.
6. Confirm that accelerator pedal is fully released, turn ignition switch “ON” and wait 3 seconds.
7. Repeat the following procedure quickly five times within 5 seconds.
a. Fully depress the accelerator pedal.
b. Fully release the accelerator pedal.
8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the MIL stops blinking and turned ON.
9. Fully release the accelerator pedal within 3 seconds after the MIL goes off.
10. Start engine and let it idle.
11. Wait 20 seconds.
12. Rev up the engine two or three times and make sure that idle speed and ignition timing are within the
specifications.

ITEM SPECIFICATION
Idle speed M/T: 650±50 rpm
A/T: 650±50 rpm (in “P” or “N” position)
Ignition timing M/T: 15±5° BTDC
A/T: 15±5° BTDC (in “P” or “N” position)