B7 S4 High idle when warm both banks lean

[DevenReilly]

When the car is warmed up the idle creeps up to around 900-1200 RPM. No misfires, pulls strong through the rev range. Have codes for High Idle and Both Banks Lean - the freeze frame shows them popping up at idle, not under load. The short term fuel trims fluctuate slowly between +3% and -3% at idle which seems right on the money. Checked for vacuum leaks all over with propane, found none. Its got a catless exhaust and havent gotten around to putting the JHM tune on it until this is figured out. Any thoughts?

[Matthewest91]

You should probably smoke test it. You can easily pass over a leak with propane.

Also clean your maf


Sent from my iPhone using Audizine Forum

[Rol-co]

When the car is warmed up the idle creeps up to around 900-1200 RPM. No misfires, pulls strong through the rev range. Have codes for High Idle and Both Banks Lean - the freeze frame shows them popping up at idle, not under load. The short term fuel trims fluctuate slowly between +3% and -3% at idle which seems right on the money. Checked for vacuum leaks all over with propane, found none. Its got a catless exhaust and havent gotten around to putting the JHM tune on it until this is figured out. Any thoughts?

Did you look at coolant sensor values?
If you clear dtc, still the same?

[DevenReilly]

I haven't looked at the coolant sensor values. I removed and cleaned the MAF, although there were no indications it was reading incorrectly. 4-6g/s at idle which seems normal. DTCs cleared, it throws the same codes within 5 miles. Did the TBA, no change. I read that fuel filter could cause this issue, I did just replace the fuel filter with an OEM one during the rebuild. Although the engine does not seems to be struggling at higher RPMs, only issue is at idle. I suspect if it was a fuel delivery issue that it would become worse with RPM and it does not.

[VinnysS4]

Lean codes but good short term fuel trims? What are the LTFT sitting at

Sent from my SM-N975U using Tapatalk

[DevenReilly]

LTFTs are sitting at around 4.7 Bank 1 and 1.6 Bank 2.

I am beginning to suspect the PCV, it was replaced with a new one during the engine rebuild, but the car is chugging oil along with the high idle. There's a lot of conflicting information on how to test the PCV valve. If I pull the oil fill cap when the engine is warm and running the idle jumps up, the STFTs jump to +12/16, and there is an audible suction noise from the PCV valve. No suction from the oil cap itself. From what I have read that either means the PCV is good or bad lol.

[Matthewest91]

LTFTs are sitting at around 4.7 Bank 1 and 1.6 Bank 2.

I am beginning to suspect the PCV, it was replaced with a new one during the engine rebuild, but the car is chugging oil along with the high idle. There's a lot of conflicting information on how to test the PCV valve. If I pull the oil fill cap when the engine is warm and running the idle jumps up, the STFTs jump to +12/16, and there is an audible suction noise from the PCV valve. No suction from the oil cap itself. From what I have read that either means the PCV is good or bad lol.

Pull the pcv apart and see if it’s ripped.
Pretty straight forward


Sent from my iPhone using Tapatalk

[DevenReilly]

PCV removed. Seems undamaged. Makes a squealing noise when I actuate it by sucking on it. Replacing anyway while its out

[DevenReilly]

PCV replaced. Noticeable difference in the amount of vacuum I get from the oil fill cap. Idle still high.