[gianttcr]

2012 135i w/N55B30a

"1st Gen" N55 motor, full-bolt on including a Kinugawa Stg3 roller-bearing PWG turbo.

71000 miles

Tuned by Stephen at Wedge. Car is making 402hp on E30 corn, at sea level. LOVE it. Tune has been on the car since winter, and reliable, so I didn't think it was that.

I have cold start turned OFF.

Car started doing this start, run, die thing about a month ago. Especially frustrating if I try to get going to soon, because it makes the DCT act up causing car to rev, lurch, rev, die, etc.

I HATE being hard on the car, so in typical BMW fashion, I started throwing parts at it over the weekend. New FCP HPFP (probably due anyway, and now I have a spare for my E92 335). Replaced the Walbro 274 in the PR bucket JIC (That's probably good too) and made a few fuel line upgrades/changes.

Car still acting up, causing me to think that I needed to remove the Radium fuel filter (not the easiest thing) and give it a clean...or else the OE regulator assembly is causing the FP to bleed down and I'll need a new one. Again, not a thrilling service to do. Only other thing could have been an electrical issue. Not fun to diag either. Also, car runs a treat once it's warmed up, and doesn't act up again until morning, so I wasn't sure what was going on.

THEN, in buttoning up the HPFP install, I realized I had A STRIPPED THROTTLE BODY TO MANIFOLD BOLT. Not sure if I did it (God knows I've had the car apart enough), or if I just missed it. I've now got a BMP manifold on order (didn't really want to add the weight to the front end, but I don't want to strip this again), and in the meantime, I went out this morning, and ran the screw back in with a thick zip-tie to take up some space in the stripped screw-hole, enough to be able to re-torque the screw.

Voila!!! Problem fixed! Idle no longer hunts.

May not work for you, but it's worth a look, as well as any other boost leak spots.