Hi All,\ first post here with a problem I can't troubleshoot.
I recently replaced the IACV and did the re-learn process. That fixed the stalling at idle problem, but now I have new issues. I a have already tried replacing the MAF and the fuel pump with no change.
- No OBD Codes, active or stored.
- The car acts like it has a soft limiter at ~1600rpm when I rev to part throttle, both in Park or driving around. Revving harder will skip past the soft limiter just fine.
- The car overrevs on a 2-3 shift at part throttle as well.
Here's a video. Thanks for your help!
Surge at Part Throttle & 2-3 Shift Overrev after IACV Change
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mdmellott
- Posts: 1269
- Joined: Mon Sep 02, 2019 3:32 pm
- Car: '13 Kia Soul+ 2.0L AT
'02 Pathfinder SE 3.5L AT P/4WD - Location: SF Bay Area, CA
Re: Surge at Part Throttle & 2-3 Shift Overrev after IACV Change
Are the following IACV relearn instructions what you followed? You referenced "another video" for this process in the clip you posted. Others have used the wrong process, referenced in previous posts on this forum, so I thought the following was worth posting if it is of any help. Your engine sounds like the IACV is not behaving well. Make note of step 7 below and it would also be advisable to check and adjust your TPS if you have not already done so.
1. Turn ignition switch “ON” and wait at least 1 second.
2. Turn ignition switch “OFF” and wait at least 10 seconds.
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic “PRE-CONDITIONING” are in good order.
5. Turn ignition switch “OFF” and wait at least 10 seconds.
6. Start the engine and let it idle for at least 30 seconds.
7. Disconnect throttle position sensor harness connector (brown), then reconnect it within 5 seconds.
8. Wait 20 seconds.
9. Make sure that idle speed is within specifications. If not, the result will be incomplete. In this case, find the cause of the incident by referring to the NOTE below.
10. Rev up the engine two or three times. Make sure that idle speed and ignition timing are within specifications.
ITEM SPECIFICATION
Idle speed 750±50 rpm (in “P” or “N” position)
Ignition timing 15°±5° 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 PCV valve operation.
3) Check that downstream of throttle valve is free from air leakage.
4) Adjust closed throttle position switch and reset memory. (Refer to Basic Inspection, EC-116.)
5) When the above four items check out OK, engine component parts and their installation condition are questionable. Check and eliminate the cause of the incident. It is useful to perform “TROUBLE DIAGNOSIS — SPECIFICATION VALVE”, EC-148.
6) If any of the following conditions occur after the engine has started, eliminate the cause of the incident and perform “Idle air volume learning” all over again:
- Engine stalls.
- Erroneous idle.
- Blown fuses related to the IACV-AAC valve system.
The IACV relearn process above comes from the Infiniti factory service manual for a '02 QX4.
https://www.nicoclub.com/service-manual ... 2%2FEC.pdf
1. Turn ignition switch “ON” and wait at least 1 second.
2. Turn ignition switch “OFF” and wait at least 10 seconds.
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic “PRE-CONDITIONING” are in good order.
5. Turn ignition switch “OFF” and wait at least 10 seconds.
6. Start the engine and let it idle for at least 30 seconds.
7. Disconnect throttle position sensor harness connector (brown), then reconnect it within 5 seconds.
8. Wait 20 seconds.
9. Make sure that idle speed is within specifications. If not, the result will be incomplete. In this case, find the cause of the incident by referring to the NOTE below.
10. Rev up the engine two or three times. Make sure that idle speed and ignition timing are within specifications.
ITEM SPECIFICATION
Idle speed 750±50 rpm (in “P” or “N” position)
Ignition timing 15°±5° 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 PCV valve operation.
3) Check that downstream of throttle valve is free from air leakage.
4) Adjust closed throttle position switch and reset memory. (Refer to Basic Inspection, EC-116.)
5) When the above four items check out OK, engine component parts and their installation condition are questionable. Check and eliminate the cause of the incident. It is useful to perform “TROUBLE DIAGNOSIS — SPECIFICATION VALVE”, EC-148.
6) If any of the following conditions occur after the engine has started, eliminate the cause of the incident and perform “Idle air volume learning” all over again:
- Engine stalls.
- Erroneous idle.
- Blown fuses related to the IACV-AAC valve system.
The IACV relearn process above comes from the Infiniti factory service manual for a '02 QX4.
https://www.nicoclub.com/service-manual ... 2%2FEC.pdf