[Stin999]

Hi everyone,

Recently I've been trying to diagnose an on going issue I've been having with my 2015 335i Xdrive. Any help would be much appreciated.

If i'm driving the car in manual mode (my car is an automatic), let's say cruising in 3rd gear, and I lift off the gas, I get an uncomfortable lurch forward sensation. The lower the RPM and gear, the worse the sensation. If I was in 1st gear and I let off the gas briefly, the car would very aggressively rock back and forth for a second before settling.

If I'm downshifting from 3rd gear to 2nd gear, I get an uncomfortable rock back and forth motion as well. Happens more so when downshifting at a lower RPMs. It kind of lurches forward and then rocks back and forth again for a brief second before settling and continuing on.

This also happens in automatic. If i'm coming a stop, it almost feels like the car doesn't want to downshift gears, and holds on to them until the very last second and then lurches me forward while quickly downshifting before coming to a complete stop.

My car has 48k miles. It's tuned BM3 Stage 1 (93 Octane). Supporting mods are MPPK intake, Fabspeed highflow catted downpipe, ER chargepipe, AWE performance mid-pipe and AWE cat-back exhaust.

Spark plugs changed within the last 4000 miles.

Transmission fluid changed in the last 1500 miles (Issue was going on before this but has progressively started to get worse).

Front and rear diff fluid changed in the last 1500 miles.

Car is running APEX EC-7's with a square setup 245/40/18 tires which were put on 1500 miles ago.

[Boostedphil698]

Originally Posted by Stin999

Hi everyone,

Recently I've been trying to diagnose an on going issue I've been having with my 2015 335i Xdrive. Any help would be much appreciated.

If i'm driving the car in manual mode (my car is an automatic), let's say cruising in 3rd gear, and I lift off the gas, I get an uncomfortable lurch forward sensation. The lower the RPM and gear, the worse the sensation. If I was in 1st gear and I let off the gas briefly, the car would very aggressively rock back and forth for a second before settling.

If I'm downshifting from 3rd gear to 2nd gear, I get an uncomfortable rock back and forth motion as well. Happens more so when downshifting at a lower RPMs. It kind of lurches forward and then rocks back and forth again for a brief second before settling and continuing on.

This also happens in automatic. If i'm coming a stop, it almost feels like the car doesn't want to downshift gears, and holds on to them until the very last second and then lurches me forward while quickly downshifting before coming to a complete stop.

My car has 48k miles. It's tuned BM3 Stage 1 (93 Octane). Supporting mods are MPPK intake, Fabspeed highflow catted downpipe, ER chargepipe, AWE performance mid-pipe and AWE cat-back exhaust.

Spark plugs changed within the last 4000 miles.

Transmission fluid changed in the last 1500 miles (Issue was going on before this but has progressively started to get worse).

Front and rear diff fluid changed in the last 1500 miles.

Car is running APEX EC-7's with a square setup 245/40/18 tires which were put on 1500 miles ago.

This sounds more like transmission related issue than transfer case. Did you ever take it in to be looked at?

[Nathen4242]

Originally Posted by Stin999

Hi everyone,

Recently I've been trying to diagnose an on going issue I've been having with my 2015 335i Xdrive. Any help would be much appreciated.

If i'm driving the car in manual mode (my car is an automatic), let's say cruising in 3rd gear, and I lift off the gas, I get an uncomfortable lurch forward sensation. The lower the RPM and gear, the worse the sensation. If I was in 1st gear and I let off the gas briefly, the car would very aggressively rock back and forth for a second before settling.

If I'm downshifting from 3rd gear to 2nd gear, I get an uncomfortable rock back and forth motion as well. Happens more so when downshifting at a lower RPMs. It kind of lurches forward and then rocks back and forth again for a brief second before settling and continuing on.

This also happens in automatic. If i'm coming a stop, it almost feels like the car doesn't want to downshift gears, and holds on to them until the very last second and then lurches me forward while quickly downshifting before coming to a complete stop.

My car has 48k miles. It's tuned BM3 Stage 1 (93 Octane). Supporting mods are MPPK intake, Fabspeed highflow catted downpipe, ER chargepipe, AWE performance mid-pipe and AWE cat-back exhaust.

Spark plugs changed within the last 4000 miles.

Transmission fluid changed in the last 1500 miles (Issue was going on before this but has progressively started to get worse).

Front and rear diff fluid changed in the last 1500 miles.

Car is running APEX EC-7's with a square setup 245/40/18 tires which were put on 1500 miles ago.

Could possible be T-Case if i'm right the tires size from BMW/ For that car is 225/45R18 I know here we cant put anything not BMW (Approved tires sizes) it can mess with the t-case even if the tires work with a tire cal (from 1010tire. if you have warranty i would get it checked out but i'd put the approved tire size back on before getting it checked.

[hollovoid7]

Mine did similar before the tc gave up at 49,500 miles (phew) my Indy said make sure you get the tire pressures set to the door jamb before taking it in to the dealer even, as bmw can be ridiculous and say "you caused it" by letting it be off.

I'm not sure if that's true, but I wouldn't risk it. Put on stock tires, inflate to recommendations, then bring in. It's too expensive to fool around with.

[328iX]

`First of all, changing your tire size does absolutely nothing, you are square, that's all that matters (or within 1%)

You are at the mileage where they typically fail, I've never noticed anything on downshifts, but when they're beginning to fail you will have a skipping feeling under acceleration, Almost as if your engine is misfiring.

That skipping will cause you to rock back and forth, but I'm unsure I'd call it a lurch.

I would take off the tune and get it checked out, they can diagnose it by disconnected the TC module and running RWD only to see if it goes away.

[brigade24]

Do you have any warning lights?

Have you tried running with the traction control completely off? i ran tires that had a slight height difference (same size but different brands) and on accel it would hesitate...felt like it was cutting fuel. so diameter matters with xdrive.

it sounds like more of a tranny sensor of some sort that the transfer case.

if you still think its the tc, you can try is running xdelete. if you install xdelete, and the hesitation continues, it may not be the transfer case. I opened up my transfer case this summer and its not the most robust unit...there's some plastic in there that channels fluids to the clutches and that plastic can break so it could cause issues.

[Assassin]

Quite possibly the cv joint in the driveshaft to the rear diff or the guibo joint at the rear of the gearbox is failing and allowing play when going fom drive to overrun.

[Jcarney32]

Sounds odd,
Im currently chasing a problem of transfercase as well. Warranty installed wrong soze front diff and probably shredded my tcase. My symptoms are my traction control light flickers and the power bogs down and wont let me accelerate if i give it some throttle past 35ish mph. It seems to be torque induced. The synptoms go away when i turn off traction control.