[smeard]

Originally Posted by rowsdower

Revisiting this issue again... I started getting secondary air pump codes but only for bank 2, which pointed to a failed O2 sensor there. I replaced both banks' pre-cat sensors, which cleared the secondary air codes but not the idle stumble.

I'm now trying to get my car through inspection and I'm not achieving readiness for fuel tank ventilation on the stock tune. I followed the procedure detailed in this thread to a T. It says to idle "in gear" for 5 minutes. I idled around a parking lot in first gear for 6 minutes, then tried holding the clutch to the floor for 6 minutes with the transmission in 1st, then tried idling in neutral for 6 minutes. No dice. I've never gotten a code for anything related to the fuel system. Any thoughts on what might cause the system to not be ready but also not throw any codes?

I did stumble upon this thread and the embedded video is exactly what I'm experiencing with my idle stumble. So I'm hoping that whatever is causing my fuel vent readiness problem is also causing my idle problem. I'd rather look into this a bit more before dropping yet another $100 in parts to replace the valve without first confirming it's the problem.

Not gonna lie, man, your story scarin' me! I just ordered headers lol. Please don't ever have the clutch in for a prolonged period of time. This is how people screw up their throwout bearing, and only way to replace it is basically doing the labor to replace a clutch, not worth it! I think the guy in that writeup may have had an auto or dual clutch. The fuel tank ventilation issue sounds like a fuel breather valve (especially if occurring after you fill up) or simply a fluke. FBV used to affect the old e46s all the time, especially SULEVs. N51 has a different, more complex fuel tank that can be more expensive to fix when something goes bad. Try going to your dealer, even if your car is modded the SULEV warranty can cover it if vehicle was first ever registered in a SULEV state and is under 15 year/150k miles. Some dealers are nicer than others, so try em all! I am kind of expecting some idle inconsistencies with headers, so long as it doesn't stall out. Hell, my current stock manifold setup stumbles a tiny bit depending if it is cold or warm. If it stumbles real bad, maybe consider getting a retune? I have known of three 128i owners who regret getting headers, but so many more who love em! I think it depends on how sensitive you are, too. Some of my mustang buddies have idle jumpin up and down and shaking the car with cams, they don't seem to care at all! Good luck, sorry this was long