[someone29926]

Hi folks - first time poster here.

Basics: 2013 328i xDrive, N26, EWG, 65k miles (first 18k in NYC, rest in sunny Southern California)

Until recently, problem free car overall minus some minor brake issues over the years.

A couple months ago, noticed some oil staining in garage about 2 weeks after an oil change. Upon inspection, appeared that OFHG was issue. Replaced the gasket, continued to experience leak. Did a dye test and found a spot around oil pan. Replaced that gasket as well. When I looked in pan during that process, however, noticed bits of timing chain guide in there. Just ripped the band-aid off and did a whole timing chain swap (+ the usual stuff that people encourage doing at the same time - replacing valve cover gasket, etc.) since I already had the subframe dropped. I did all of this work myself. I generally followed every instance where I was supposed to 'renew' bolts and fasteners, at least where related to non-suspension bits, and I torqued everything to spec. Whether it was already this way, or whether it happened in process, I did realize the turbo intake pipe was damaged where it connects to the turbo inlet, which seems to be common. So I replaced that as well (what a shamefully idiotic placement of the 10mm holddown nut on that one btw ...)

Put everything back together and started right up without issue. Seems to be running better than ever tbh. Something I did even solved a long-time rattle issue that had been there since like 5k miles . BUT - before my car was ready for emissions check, only waiting for the O2 sensor test to complete, it threw up a P0171 code. I see there is no shortage of references to this code on this forum and the internet writ large, but I'm just wondering given that mine specifically came up right after a timing chain swap and had never been seen before that, does that give any hints/clues as to where I might focus? Should note my car is completely stock, and many other examples seem to boil down to different intakes, tunes, etc. that wouldn't be relevant here.

If you are thinking vacuum leak, so was I...so I bought a smoke machine off Amazon, removed the pressure sensor from throttle body and pumped full of smoke. I didn't see even a wisp of smoke popping out anywhere. Now, if I disconnect the airbox and pump the smoke into the air intake just behind the MAF, there are definitely wisps that come out at both the place where the crankcase vent connects to that intake pipe (more) and the turbo inlet itself (less). As mentioned earlier, I did replace this intake pipe, and I did use a generic non-OEM off of Amazon. Maybe it's as simple as that and the tolerances just aren't tight enough. But I don't even know if I'm doing this whole smoke test thing right. It did occur to me, if I'm pumping that pipe full of smoke, I'm introducing positive pressure into the system, which as I see it pushes seals/o-rings away from where they are supposed to be, whereas vacuum (their actual operating condition) would tend to do the opposite. I would note also that it starts to 'leak' only once that pressure has built up a good bit inside, and not right away. Basically I'm just really not looking forward to replacing that pipe again - given the stupid placement of that 10mm nut mostly - especially now that everything else is back in place, and hoping someone has some other ideas for what I might try first.

FWIW I do have access to ISTA although very little experience in actually using it.

Thanks in advance.

[someone29926]

A couple things to add, for what they're worth:

1. Have logged a number of drives using OBD Fusion that encompass a cold start-up, up to sustained ~75mph on highway. Have not observed LTFT outside of 6-8% max. STFT have spiked to ~20%, but hover right around zero overall. Given that I thought the P0171 code wouldn't even get set until LTFT was elevated to 25%+ for some period, I found this quite curious...using ISTA, I can see that the hex code 118001 - this doesn't seem to give any extra info unfortunately. The frequency for the code is 1 (set a few days ago) and the 'healing count' is 37, which would seemingly imply that my last few drives have not experienced the lean condition.

2. Again using ISTA, I do see an error code related to the oil pressure sensor. This is somewhat interesting because, as I neglected to mention earlier, I actually did replace this as well in my attempts to plug anything that might be leaking oil. It would appear to be an OEM replacement, but given it came from Amazon...wouldn't want to rule anything out. Even more interesting to me is that OBD Fusion does not list any code related to this, and I am not shown any warning lights on the dash at all. I also wouldn't normally think this has anything to do with the lean condition, but I've actually found a few references around the internet which seem to suggest it's not impossible, or at least that one issue could be confounding the other.

My primary goal here is to pass emissions in California asap - I'm unfortunately well overdue for my smog check - and buy myself time to diagnose/remedy this properly, since this does seem to be something of an intermittent issue and again, by the seat of the pants, the car is running great. I am more than willing to get creative here to that end. Theoretically I could clear all the codes (I have no permanent codes set, or even confirmed ones...only the pending P0171, so easy enough to clear that out) and go through one 'drive cycle' as outlined at https://f30.bimmerpost.com/forums/sh....php?t=1677541, before heading straight to smog check and getting OK before code comes back...but the last 2 attempts at doing so have both resulted in P0171 coming up pending again before all emissions tests cleared.

Thanks again for any ideas...