2015 Chevrolet Sonic 1.8L
Hey guys, I'm working on my girlfriend's car and I don't know much about GM vehicles. I'm a Nissan Master Tech and I know Nissan's don't purge at idle, but apparently my girlfriend's Sonic does. I'm going to try to make this as short and sweet as possible.
What I know:
-Vehicle set P0171 fuel system lean bank 1. LTFT hovers around ~28% at idle.
-Intake tube is not torn.
-PCV in valve cover is not leaking.
-Purge valve itself appears to be operating normally and not leaking when trying to blow air through it. However, I do have a new one coming in the mail because it was only $20.
-Visually everything under the hood is hooked up or plugged in and I cannot locate any obvious vacuum leaks using the brake cleaner method.
-ECM commands ~13% duty cycle on the purge valve at idle. When this happens the EVAP pressure sensor is usually somewhere around -160 to -200 pascals.
Now with that being said, I have watched the fuel trims with the vehicle running and noticed the values only increase (lean condition) when the purge valve is commanded on at idle. If I disconnect the purge valve and plug it with my finger the fuel trims return to 0% where they should be.
I have come to the conclusion that there must be some sort of air leak in the EVAP system somewhere down the line. Are there any common EVAP issues with these vehicles that you guys have seen before I borrow a EVAP smoke machine from a friend?
Lastly, can someone give a brief description about how the Sonic's EVAP system is supposed to operate at idle? I can't find any information on ECM logic.
Hey guys, I'm working on my girlfriend's car and I don't know much about GM vehicles. I'm a Nissan Master Tech and I know Nissan's don't purge at idle, but apparently my girlfriend's Sonic does. I'm going to try to make this as short and sweet as possible.
What I know:
-Vehicle set P0171 fuel system lean bank 1. LTFT hovers around ~28% at idle.
-Intake tube is not torn.
-PCV in valve cover is not leaking.
-Purge valve itself appears to be operating normally and not leaking when trying to blow air through it. However, I do have a new one coming in the mail because it was only $20.
-Visually everything under the hood is hooked up or plugged in and I cannot locate any obvious vacuum leaks using the brake cleaner method.
-ECM commands ~13% duty cycle on the purge valve at idle. When this happens the EVAP pressure sensor is usually somewhere around -160 to -200 pascals.
Now with that being said, I have watched the fuel trims with the vehicle running and noticed the values only increase (lean condition) when the purge valve is commanded on at idle. If I disconnect the purge valve and plug it with my finger the fuel trims return to 0% where they should be.
I have come to the conclusion that there must be some sort of air leak in the EVAP system somewhere down the line. Are there any common EVAP issues with these vehicles that you guys have seen before I borrow a EVAP smoke machine from a friend?
Lastly, can someone give a brief description about how the Sonic's EVAP system is supposed to operate at idle? I can't find any information on ECM logic.
