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MotorvateDIY Video: Easy Idle Air Volume Learning

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Old 08-10-2018, 10:27 AM
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MotorvateDIY Video: Easy Idle Air Volume Learning

For those who have struggled to get the "Idle Air Volume Learning" after cleaning the throttle bodies, here is an easy way using a free app:
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Old 08-10-2018, 01:42 PM
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Sweet thanks!!
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Old 08-10-2018, 05:32 PM
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Glad to help
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Old 08-10-2018, 08:58 PM
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@ MotorvateDIY Good find. The permissions don't look too bad either. I run a firewall on my device (rooted), and any new app must explicitly be given network (lan, wifi, or mobile) access.

So, anyone clean their TB's lately and use this app to reset?
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Old 08-12-2018, 03:39 PM
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It's a sunday afternoon and I have nothing better to do.

Car is almost 7 years old, ~30K miles. No, I didn't clean the TB's, that will be a project for another day. Figured it would hurt to recalibrate things after this much time/mileage. Did the 2 initial resets then the idle air volume. Follow the instructions closely. Among other things, it's vital the electrical load be as minimal as possible. Was closely watching the rpm as the car warmed up to ~180F. Rpm was relatively consistent but did have a peak every once in a while that could be felt. Once the relearn was performed, it was very steady. Slight fluctuations between 638 to 650 rpm were noticed in the readout but not felt. I think 12 rpm is the small rpm detectable either by the sensor or a result of A-D conversion.

Placebo or the result of the relearn.....? We'll see if there's any change once I actually drive the car someplace.

Also noticed when the ac is turned on, idle rpm jumps to about 800 and the fans kick on right away (thermostat as temp is ~195F). It then slowly comes back down.

I did the whole thing with the phone in airplane mode. With the app running for 5 or 10 minutes, a message did come on that internet is required to continue using the app. Closing/reopening the app reset the timer. Also, when conditions are met, the reset should occur before the counter reaches 200. If it's going beyond that, there is some issue.

Note, I used a PLX kiwi BT dongle. This is the original one I got a number of years back (2011 or 12). They now have version 2 and 3. 3 is on sale for $85 from the mfg https://www.plxdevices.com/Kiwi-3-OB...7346002832.htm .

Other dongles probably work too, but back then I had lots of timing issues with the generic ones and eventually got one.
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Old 08-21-2018, 09:26 AM
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@ Jsolo,
Not that it really matters, but the RPM PID ($0C) has a scaling factor of .25 RPM per bit, so in theory, it should be accurate to 1/4 RPM.

Our latest episode show how to use any OBD scanner & app to see how dirty your throttle body is:
My guess is that your relative throttle position is < 0.5%
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Old 08-21-2018, 12:25 PM
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@MotorvateDIY Could be how the software averages/smooths the numbers too. I think torque (which is what I paid for) has an option to configure samples/time unit or something similar.

I'll connect to the car soon to see what my values are for the relative/absolute positions. In the video you mention the car should be at hot idle. You think under a cold start the tb's are closed further than what they would be at hot start? Did you notice a difference in values cold vs hot?

Btw, after doing all the resets, I can't say I've noticed any change in performance other than the slightly smoother idle as noted earlier. Throttle response seems identical to before. Over the course of a 2000 mile road trip, no real change noted in mpg either. Driving at 65mph or under produces best numbers, but at that speed I was even getting passed by [email protected]#

Best leg of the trip was from Mexico, MO to home, ~60 mph on county highways, 65 on the interstate, 428 miles, 27.8 mpg. I was tired and taking it easy. Worst was going through the ozark mountains, 24.5. Lots of 30-45 mph turns uphill, usually in 3/4/5th gear. Still respectable.

Edit:
With the car on but not running, absolute for both is at 3.9%. I don't drive daily so will check it again next time I actually go someplace.

Last edited by Jsolo; 08-21-2018 at 01:47 PM.
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Old 08-21-2018, 01:48 PM
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Since we now have an easy way to do the tb relearning, does it matter any more if the tb harnesses are disconnected during cleaning?
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Old 08-21-2018, 02:42 PM
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@Jsolo
If you disconnect the throttle body harness, make sure you perform the Throttle valve closed position learning, then the idle air volume and you are good to go.

The throttle is open a little more at cold idle and that is why the cold idle is around 1,000 RPM. As the engine warms up, the throttle closes slightly and the idle drops to 600-700 RPM. That is why all the diagnostic reports were at "hot idle" to make sure I get the typical operating conditions.

With the ignition (key) on, and engine off (KOEO) the throttle bodies are open MORE to help start the engine. When the engine has started, they start to reduce the throttle opening, and the idle lowers.

By the way, a dirty or clean throttle body will have zero impact on fuel economy.
A very dirty throttle body can result in the engine starting for a seconds, then stalling.
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Old 08-21-2018, 03:01 PM
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Thanks for clarifying. I'll have more accurate data tomorrow after driving it some.

On the topic of android apps, how well does obd fusion support nissan specific PIDs? I only saw references to this for their windows software. I already have the paid version of torque and the nissan addon.
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