Idling up and down from 1200 to 2000 RPM

Hi and thanks for using 2CarPros. Com.

Based on your description, it sounds like there is a problem with the IACV-AAC valve. This system automatically controls engine idle speed to a specified level. Idle speed is controlled through fine adjustment of the amount of air which by-passes the throttle valve via IACV-AAC valve. The IACV-AAC valve changes the opening of the air by-pass passage to control the amount of auxiliary air.

Now before just replacing the valve, check to make sure there is no carbon build up on the throttle plate. If it appears clean and closing properly, then remove the IACV-AAC valve and inspect it for carbon or any dirt.

I have attached a picture of the component and location for you. If the valve is to be replaced, there is a relearn process that requires Consult II scanner or equal. Here is the relearn process with a manual transmission. Starting with picture 2, the remaining pictures correlate with these directions.
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DESCRIPTION
"Idle Air Volume Learning" is an operation to learn the idle air volume that keeps each engine within the specific range. It must be performed under any of the following conditions:
- Each time IACV-AAC valve, throttle body or ECM is replaced.
- Idle speed or ignition timing is out of specification.

PRE-CONDITIONING
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 12.9 V (At idle)
- Engine coolant temperature: 70 - 99° C (158 - 210° F)
- PNP switch: ON
- Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime running light Systems, set lighting switch to the 1st position to light only small lamps.
- Cooling fan motor: Not operating
- Steering wheel: Neutral (Straight-ahead position)
- Vehicle speed: Stopped

OPERATION PROCEDURE

With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check that all items listed under the topic "PRE-CONDITIONING" (previously mentioned) are in good order.
3. Turn ignition switch "OFF" and wait at least 10 seconds.
4. Start the engine and let it idle for at least 30 seconds.
5. Select "IDLE AIR VOL LEARN" in "ACTIVE TEST" mode.
6. Touch "START' and wait 20 seconds.
7. Make sure that "CMPLT" is displayed on CONSULT-II screen. If "INCMP" is displayed, "Idle Air Volume Learning" will not be carried out successfully. In this case, find the cause of the problem by referring to the NOTE below.
8. Rev up the engine two or three times. Make sure that idle speed and ignition timing are within specifications.

ITEM SPECIFICATION
Idle speed M/T: 625 ± 50 rpm
A/T: 700 ± 50 rpm (in "P" or "N" position)
Ignition timing M/T: 15° ± 2° BTDC
A/T: 15° ± 2° BTDC (in "P" or "N" position)

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Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check that all items listed under the topic "PRE-CONDITIONING" (previously mentioned) are in good order.
3. Turn ignition switch "OFF" and wait at least 10 seconds.
4. Start the engine and let it idle for at least 30 seconds.
5. Disconnect throttle position sensor harness connector (brown), then reconnect it within 5 seconds.
6. Wait 20 seconds.
7. Make sure that idle speed is within specifications. If not, the result will be incomplete. In this case, find the cause of the problem by referring to the NOTE below.
8. Rev up the engine two or three times. Make sure that idle speed and ignition timing are within specifications.

ITEM SPECIFICATION
Idle speed M/T: 625 ± 50 rpm
A/T: 700 ± 50 rpm (in "P" or "N" position)
Ignition timing M/T: 15° ± 2° BTDC
A/T: 15° ± 2° BTDC (in "P" or "N" position)

NOTE:
If idle air volume learning cannot be performed successfully,
proceed as follows:
1. Check that throttle valve is fully closed.
2. Check that downstream of throttle valve is free from air leakage.
3. Adjust closed throttle position switch and reset memory. (Refer to Basic Inspection.)
4. When the above three items check out OK, engine component parts and their installation condition are questionable. Check and eliminate the cause of the problem.
5. If any of the following conditions occur after the engine has started, eliminate the cause of the problem and perform "Idle air volume learning" all over again:
- Engine stalls.
- Erroneous idle.
- Blown fuses related to the IACV-AAC valve system.
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I hope this is helpful. Let me know if you have other questions.

Take care,
Joe

Welcome back. Has the check engine light come on? If it has, have you scanned the computer to determine if there are trouble codes?

Next, have you checked for engine vacuum leaks?

Let me know,

Joe

Welcome back.

That is good news. You are right, maybe the cleaner finally hit the right spot so to say. Regardless, let me know if you need anything else.

Take care and have a good weekend (it is nearly Friday).

Joe

Welcome back.

Has the check engine light come on? Also, check the wiring at the IACV. Wiggle the connector with the engine running to see if it changes anything. It is acting like the IACV is bad.

Interesting. I still feel it has something to do with the IACV. Try moving the harness around and wires to see if it changes. Also, remove it and inspect for debris/carbon.