victell- my '01 X5 3.0i has had a similar problem with lean codes and also showed a misfire code
P1345 - Misfire cylinder 2 with fuel cut off, IIRC, just once, in the 2.5 years I've owned it, but I've not yet located the source of the problem, yet. Fortunately, I've used a work-around to keep the CEL/SES/MIL boogeyman away, since the problem started.
The difference between your X5's problem and mine is that mine has never had any driveability problems, with the engine having had just about everything renewed in the three years before I traded for it (by the PO, specifically as the conditions that our car-for-car swap demanded), including plugs, coils, O2 sensors, vcg, Vanos, chain & guides. The only components I've had to change are the exhaust cam position sensor (two codes thrown concerning that was enough warning for me!), a new oil cap & gasket (some blow-by on top of the beauty cover), converting the noisy & cracking viscous fan assembly for a hi-power electric fan, and lastly, swapping the OE MAF sensor for a $20 Amazon unit (more details later).
I followed much the same path you've tread, testing with a homemade smoke tester, out in the open, with the same results you had, for the same reasons, but I've also used carb cleaner spray (which I've used previously on other cars to find vacuum leaks) with similar zero finds. Visual inspections also negative, as was the fuel pressure test (the regulator was brand new, I found out later, so I wasted $75 for the tester and attachments, I guess), and I rebuilt the DISA valve with a G.A.S. kit, so there would be no question concerning it.
I've used a Foxwell NT510 Elite to graph O2 sensors, also, and they were OK, looked at all the live data, compared readings before and after adaptations cleared, and have done hundreds of test sessions using it and once or twice using INPA (but prefer the Foxwell). Nothing much to see, except high fuel trim numbers on both banks.
Concerning fuel trims: mine were so high back in late '21 and early '22, that I'd get the "money light" on (as Eric O. on South Main Auto youtube channel likes to say), and as the next emissions inspection was coming up, I tried taking out my OE MAF sensor (Siemens), which I had previously cleaned with the proper cleaner several times, and replaced it with a $20 ($23? at the time) Chinesium "MostPlus" sensor from Amazon.
X5chemist had suggested doing that, as he had much earlier (and still reports that his is performing fine, now 2+ years later).
Immediately, after the swap (and resetting the fuel trims to zero), my MAF readings were much better, and correspondingly the LTFT's (long-term fuel trims) have become lower (better) ever since, though they are still going as high as +9% long-term, in stop-and-go low-speed driving (which is 99% of the only 1500 miles...in the 2.5 years I've driven it), and the long-terms fall to as little as +4%, during the very few extended highway trips it's been on). Either the OE MAF was underreporting airflow, or the cheap replacement is overreporting it, but it's been a good work-around, that I can live with (the X5 passes inspections, the exhaust smells clean, and it is what it is). I had an Amazon refund coming awhile back, so I used it to get a second cheap MAF, as a spare!
Back in Oct.-Nov.'23, I was shopping for a factory-built professional (or semi-pro) smoke tester, after I figured my two previous home-built testers were insufficient. After much ado, after getting & sending back, two cheap-ish units that were broken or defective as built, I finally ordered a better one (which the two cheap others were clearly clones of), the
AutoLine Pro EVAP Smoke Machine Leak Tester – Shop Series https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1
from Amazon, to further test my X5 for the phantom vacuum leak I'm sure that MUST be out there, somewhere.
I've got vacuum caps, replacement silicone hoses, and clamps standing by, waiting for the day when I can take over the single garage bay that my wife's
precious Lexus sits in, take out the obstructing plastic crap covering the rear of the engine, and smoke test the X5 again. We live on a semi-rural sandhill, with wind-blown sand & oak debris always present (plus feral cats, squirrels, rats, mice, scorpions, spiders, snakes,etc. always trying to get into the garage), so I usually can't open up dust & dirt sensitive components or areas, while outside on my plywood work platform, that I use for external component maintenance.
I also have halogen & LED worklights, an endosope, inspection mirrors, Rhino Ramps (so, in case I suspect a vacuum leak near the fuel pump, I can get under there), etc., standing by, but things keep popping up to prevent my smoke test.
- 1) holidays,
- 2) cold or wet weather (N.Texas type),
- 3) constant ongoing projects that my wife needs my help on,
- 3) old age health (73 y.o.),
- 4) just in the last two weeks: the precious Lexus started up smoking & sputtering, so I opened up the engine covers, found a rodent nest, inspected for damage (found none), tested (with Foxwell & Torque Pro app for codes, and found none), then ....see this thread https://www.clublexus.com/forums/es-...r-coolant.html
So, now I'm going to smoke test two vehicles (guess whose vehicle will get tested first, hahaha), to find what, if anything, is really amiss.
victell- I wish you luck, I'm hoping you find something, anything, as a longtime mystery problem can drive one nuts, after awhile.