2016 CX-9 DTC Code P0171 - Engine Revving Up and Down When Idling - Purge Solenoid

[Duke Yugo]

My 2016 CX-9 started to rev up and down when parked and idling. DTC code is P0171 "System Too Lean".
When in Drive, I can feel it a bit staggering and the RMP dial "dancing" when stopped.
I think it is the Mass Air Flow Sensor, but I am not sure.
Any help is greatly appreciated.

Link to YouTube video: https://youtu.be/DODJAZs0Qbc

 

[sm1ke]

Many years ago I had a car that started doing this. First thing I would check is to make sure there are no leaks in the air intake system - check the piping and the clamps to make sure they are tight. Check for any holes or cracks in the tubes. After that I would try cleaning the MAF sensor (use the correct product for this). If that didn't work, I might consider a replacement MAF sensor.

 

[PTguy]

The throttle body can use a good cleaning occasionally. This is an example of one brand.

https://www.wikihow.com/Clean-Mass-Air-Flow-Sensor
https://www.wikihow.com/Clean-Throttle-Body

 

[Duke Yugo]

It's not the Mass Air Flow Sensor.
Replaced it and it's doing the same thing.
The hunt continues.

 

[Z31]

Is this happening all the time? Or only cold start? Or once it's warmed up?

I had a Toyota with a bouncy idle when it was cold; it would get in a weird feedback loop, but once it was warmed up it was okay.. It was intake manifold gaskets, an minor fix.

Have you or garage ever had the intake manifold off? Perhaps to clean carbon build up?

 

[Duke Yugo]

I used Gumout Intake Valve and Turbo Cleaner to see if there would be any difference, but there is none. The car still behaves the same, whether it's cold or warm.
About a year ago, the cylinder head was replaced under warranty due to a known issue with a crack and coolant leak.

 

[Duke Yugo]

It was the purge valve, also known as a purge solenoid or canister purge valve.
Running great after replacement.
Hope this post helps others.