[t335xi]

Over the past 6 months I've noticed the turbo lag has increased and general smoothness of throttle is gone. The engine seems very underpowered like im not even stepping on the gas and then the turbo kicks in hard 2 to 5 seconds later and the car almost seems to overboost. I have a 335xi w mppk and the sport+ transmission options. This problem happens in any driving mode but I'm most concerned that it's happening in sport and sport plus modes. Those modes should have power readily available and very little lag or at least they always used to for me. Also the car is warmed up and I'm using the highest octane fuel. My car is rounding the 48k mileage mark and has a clean bill of health as far as I know.

I've tried flipping it to Manuel to keep the revs right at 3k before stepping on the gas and that still does not help alleviate the lag.

Do these cars just stop performing well at 50k mileage?

Any ideas on how to fix this. I've read it could be carbon buildup on injectors but is there anything else?

[mge92]

Try reseting your foot pedal by putting the car into accessory mode or just turn on the car by pressing the start button WITHOUT the brake pedal. Then go ahead and depress the accelerator all the way to the floor past the click point. Hold the pedal down for 30 seconds then proceed to switch the car off. Now restart the car and it should help.

You could also try the italian tune whereby you put the car in the manual shifting and while driving, keep the revs around 4-5000 rpm and get the engine temperature up to about 250 F + but below the 300 F mark. Drive for about 15 mins.

[stupidfastwagon]

Did you get the valves walnut blasted? You could have excessive carbon build up that is causing the car to act sluggish. Who does your service?

[t335xi]

I have a stealership apt this week hopeful that the walnut thing will be covered under warranty.

I have reset the throttle doing that on off pedal down thing in the past but it doesn't seem to zero out the lag.
I remember the first 30k miles i had the car the acceleration was fierce and linear and i never felt under powered;
Compared to now where accel is really almost unpredictable.

[G30 B58]

Boost leak? Chargepipe?

I have no idea what I'm saying, this is my first turbo car.

[drexplode]

Disconnect the battery for >1h.

replace the following if you haven't done already: spark plugs, and air filter. Never hurts to do an oil change after spark plug replacement as well.

If that doesn't work then probably carbon build-up which requires cleaning.

[Shahdog]

Possibly carbon buildup


Need walnut shell blasting


Or at least their foam cleaner

[RM7]

Originally Posted by F32 N55

Boost leak? Chargepipe?

I have no idea what I'm saying, this is my first turbo car.

This is the most common loss-of-power issue with turbo cars. Usually to a hose clamp that has worked it's way loose or at worst, a torn/eaten through hose/tube.

[smithf80]

Pretty sure 50k becomes the interval plugs with MPPK.

Spark plugs and walnut blasting.

It will feel like day 1.

[mge92]

Try the Italian tune up

[t335xi]

ha i do the "Italian" tune up everyday on the on ramp. I dont think that works with DI though am i right

[mge92]

Well you have to keep the revs up at the 4-5000 rpm range and keep it there for a couple miles and get the engine temp higher than it normally is. Helped fix my sluggish n20.

[Professor///M]

Spark plugs need to be changed at 40K for MPPK. Give that a shot

[Vegetable]

Originally Posted by JSTDR1V

Spark plugs need to be changed at 40K for MPPK. Give that a shot

Is this covered under the maintenance program

[DTP1980]

Every throttle/ turbo lag issue I have experienced with BMW cars has been as a result of the air mass meter failing, despite no engine light.

You might try cleaning it very very carefully with an appropriate type of cleaner found your side of the pond. If that doesn't fix it, I would replace it anyway. It's as important as the throttle cables, which we no longer have, as it's the primary communication tool between your foot and the engine.

[Professor///M]

Originally Posted by Vegetable

Is this covered under the maintenance program

Yes. Some won't replace before 45k though

[Vegetable]

Originally Posted by JSTDR1V

Yes. Some won't replace before 45k though

I just asked my SA when my 2014 MPPK 435i needed its spark plugs changed and he said it was 65K miles.. I had planned on changing at 50K and just pay for it...

[Professor///M]

Originally Posted by Vegetable

I just asked my SA when my 2014 MPPK 435i needed its spark plugs changed and he said it was 65K miles.. I had planned on changing at 50K and just pay for it...

With my e90 they said it was part of the year 3, or 45,000 mile service, and wouldn't pull it ahead. Didn't realize they changed it for F30.

[t335xi]

just got it back from the shop. New plugs and the rear suspension was leaking and broken. The new suspension alone seems to have corrected it. maybe my car was just squatting due to the break.