Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
16 sonata has a p0172. Definitely running rich. Stft and ltft are negative at idle. When driving they start to go positive and even out. Then go negative at idle. A/F sensor changes with simulated lean condition(pulling vacuum hose) and so does o2 sensor. No sensor is stuck. Does not have a maf. Map reading is ok. About 1.2V at idle. Did find clogged air filter but no change after replacement. Check for clogged cat. Checked ok. Leaning towards leaking injectors. Has anyone experienced this on a GDI system? Can i test the injectors using a fuel pressure gauge and pulsing the injectors with an injector tester? Not sure if that works on a GDI. Any input is appreciated. Thanks in advance.
It works the same as the test you were mentioning except you are using the scan tool to bidirectionally do the test. GDI injectors are low resistance so using a tool to pulse them may not be a good idea. In this case it’s likely not even necessary.
Do you have proper fuel pressure? Monitor fuel pressure for 5 minutes after vehicle is off to see if you have injector leakage. Also be weary of temperature sensors causing an over fuel lung issue.
Making Pressure Differential Sensors (PDA Sensors) for pressure pulse diagnostics.
Currently servicing Central Texas.
Thanks for your reply. Ill have to check pressure again. The pressure specs and how the scan tool measures pressure were different if i remember right. I did the best I could using voltage from the fuel rail pressure sensor and the spec sheet. Looked to be ok. I can only disable injectors with the vehicle running. I did notice that cyl 234 did not have significant drops in rpm when disabled. And cyl 1 had a significant drop. Would you say cyl 1 injector is working properly and 234 are possibly leaking causing an insignificant drop or the other way around. Thoughts?
Update. So I Teed in a fuel pressure gauge on the low side and found the fuel pressure dropping about 1 psi every few minutes. I unbolted the high pressure pump. Lifted it above the valve cover with the hard line still hooked up. Could see fuel slowly seaping out of the pump. Had to look closely and clean before. I can imagine the leak being more aggressive when the engine is running.
Thanks for getting back to us with an update! I imagine it wouldn't take long to thin the oil out at that rate.