High idle after cleaning throttle body (one more time!)

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ShipFixer
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High idle after cleaning throttle body (one more time!)

Postby ShipFixer » Thu Apr 14, 2011 6:41 pm

While I was changing out my tensioner pulley, I thought I'd take a quick stab at cleaning out my throttle body since I read about others doing it here. Well, now I wish I hadn't. I can't get the check engine light to go away, and I've been through the ECU reset procedures maybe ten times now.

I tried reseating the throttle body on the rubber gasket...no luck. This isn't an air leak or vacuum problem.

I see numerous threads here and in other forums where people had this problem, and then never posted what ultimately fixed it. Do I just keep trying the ECU reset until it miraculously works, or go in to a Nissan dealer somewhere around here?


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pawjr74
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Postby pawjr74 » Thu Apr 14, 2011 6:52 pm

Just an FYI...you will need to do ALL these procedures if you clean your trottle body!

Link from nicoclub.com: http://forums.nicoclub.com/05-pathfinde ... 44342.html

This problem is perfectly normal after cleaning/replacing the throttle body. Over time as your throttle body collects carbon the air volume which passes through it changes very slightly. This slight change in air volume is registered by the ECU and the ECU will auto-correct itself over time so that the driver notices no difference in idling or throttle response.

When you cleaned the throttle body you increased the air volume which can pass through the throttle body and this confused the ECU into thinking that there is something wrong with the engine, causing the malfunction indicator lamp to illuminate.

There are some steps which you can take to remedy this problem, all of which are free and can be done in your driveway. The following tasks need to be performed in the following order:

1. Reset ECU

2. Accelerator Pedal Released Position Learning

3. Throttle Valve Closed Position Learning

4. Idle Air Volume Learning

-----------------------------------------------------
----- RESET ECU -----
(The easy method below is much easier than this one, I suggest trying that one first)

1. Confirm that accelerator pedal is fully released, turn ignition switch “ON” and wait 3 seconds.

2. Repeat the following steps (2a and 2b) procedures quickly five times within 5 seconds.

2-a. Fully depress the accelerator pedal (HARD).
2-b. Fully release the accelerator pedal.

3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the CEL starts blinking.

4. Fully release the accelerator pedal (while the CEL is still blinking).

5. Wait about 10 seconds.

6. Fully depress the accelerator pedal and keep it for more than 10 seconds.

7. Fully release the accelerator pedal (The CEL light will continue to blink).

8. Turn ignition switch to “OFF” position and now you can start the car. The CEL light should be gone.

If the CEL light continues to remain ON, repeat the above steps. Timing is EXTREMELY critical to resetting the ECU.

----- EASY METHOD TO RESET ECU -----

1. Ignition "ON", count to 3.

2. Depress/Release pedal 5 times...hard and fast.

3. Count to 10 (not 7!) and fully depress pedal

4. Count to 12 (SES should be blinking), release pedal

5. Count to 10, depress pedal

6. Count to 10, release pedal.

7. Turn off ignition, then start engine. Done!

----- ACCELERATOR PEDAL RELEASED POSITION LEARNING -----

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 -----

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 -----
(The following steps are very time critical and any errors in timing may cause the malfunction indicator lamp to illuminate. If this occurs, you need to reset the ECU and complete all of the tasks again)

1. Start engine and warm it up to normal operating temperature.

2. Check that all items listed under the topic PREPARATION (previously mentioned) are in good order.

3. Turn ignition switch OFF and wait at least 10 seconds.

4. Confirm that accelerator pedal is fully released, then turn ignition switch ON and wait 3 seconds.

5. Repeat the following procedure quickly five times within 5 seconds.

5-a. Fully depress the accelerator pedal.
5-b. Fully release the accelerator pedal.

6. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the MIL stops blinking and turned ON.

7. Fully release the accelerator pedal within 3 seconds after the MIL turned ON.

8. Start engine and let it idle.

9. 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. The vehicle should idle at 625 RPM's.

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pawjr74
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Postby pawjr74 » Thu Apr 14, 2011 6:53 pm

I did it successfully on mine.

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ShipFixer
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Postby ShipFixer » Thu Apr 14, 2011 7:20 pm

Been doing all of the steps, and traced them back to the service manual to make sure that they were correct. I saw the thread where you went through this...you didn't have to do anything different? Did it take a few tries?

I've used a stopwatch...this just can't be that hard...

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pawjr74
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Postby pawjr74 » Thu Apr 14, 2011 9:28 pm

One or more of the steps I had to do a couple of times. I can't remember which ones now.

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ShipFixer
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Postby ShipFixer » Thu Apr 14, 2011 10:04 pm

I think the "easy" ECU reset works okay for me. Should the idle decrease to 625 at that point or only after the idle air relearn? It hasn't dropped below 900 rpm yet for me at any step, although the reset is turning off the service engine light for a while.

Out of curiosity, did you hear the throttle valve clicking or something during a couple of the steps? I think thats what I hear, particularly during the idle re-learn when you hold down the pedal for ~20 seconds.

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pawjr74
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Postby pawjr74 » Fri Apr 15, 2011 6:09 am

I don't remember hearing any clicking but after the idle re-learn it dropped instantly from 1000 rpm to 625 rpm.

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ShipFixer
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Postby ShipFixer » Fri Apr 15, 2011 6:44 am

I must be screwing up on the idle relearn then. I have a couple ideas, hopefully this doesn't take all weekend to figure out. It's definitely sucking down gas more quickly and I'd planned on taking some mountain bike oriented road trips...

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ShipFixer
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Postby ShipFixer » Fri Apr 15, 2011 2:43 pm

Still can't get this to work! I'd thought that maybe it was the transmission not being warm enough. Running out of ideas here...idle is getting no lower than 800 rpm...

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ShipFixer
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Postby ShipFixer » Fri Apr 15, 2011 11:49 pm

Fought this for the better part of the evening. It looks like my truck may be trying to tell me it has a trouble code but it's not coming out in four clear sets of blinks as per the manual. So tomorrow I'm going to pick up a code reader and see if it says anything before asking Nissan for help. Hopefully I can find one open on a Saturday...

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volvite
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Postby volvite » Sat Apr 16, 2011 5:27 am

If buying a reader, I'd recommend getting something that will last you awhile. Spend the money upfront and you'll be happier in the long run that you bought something that tells more than just the code.

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ShipFixer
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Postby ShipFixer » Sat Apr 16, 2011 4:10 pm

I picked up a scanner from Autozone and still haven't learned anything. The only code it throws out is for high idle. It says that some of the onboard tests are incomplete (EVAP, O2, etc) but since part of this procedure is mind-wiping I don't think that should prevent an idle reset.

I do see that one of my O2 sensors is reading 0.6V where the others read 0.3-0.4 like disallow's. But I also don't think that should be an issue either.

Idle is currently sitting at 925 and I can get it to go any lower...help please...

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ShipFixer
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Postby ShipFixer » Sat Apr 16, 2011 4:58 pm

Here's a question for others who did this...did you remove the throttle body from the intake manifold or just clean it in place? I removed mine, and went back and tried lubing the gasket to see if that was it. Haven't tried spraying with carb cleaner to test directly for a leak...

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ShipFixer
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Postby ShipFixer » Sat Apr 16, 2011 6:05 pm

Oh well, not an air leak...

Tomorrow I'm going to try disconnecting the throttle body harness and respraying the internals. Maybe the ticking noise isnt right...

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ShipFixer
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Postby ShipFixer » Sun Apr 17, 2011 3:49 pm

Well, nothing works. Once or twice the throttle started to go down during idle learning but only for a couple seconds. Refused to go below 3.1% or 850 rpm. Sensor appears to be fine since pushing it past the return spring to fully closed sends it to zero correctly. Looks like I'll be trying to catch a local Nissan dealership late tomorrow or Tuesday...


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