throttle response / Turbo lag

[Coyner]

Hi Folks,

I just bought my first 1M coupe which has a Lichtfield remap and a Millteck cat-back exhaust. Compared to a N/A car the throttle response is slow and lagging and mot linear .... slow to respond then huge boost. Things are much better with M button depressed but nothing like for example a Porsche 997.

I have never driven a stock car ..... is that just how these engines behave or does it sound like there might be something wrong?

Thanks folks!

[CarJunkie]

In stock form, the DME targets 11psi which the turbos reach effortlessly, but it leaves a LOT of midrange torque on the table. Your tune is probably targeting 16-17 psi in the midrange and that will take more time for the turbos to spool up to, making the lag more noticeable. A larger intercooler also produces additional lag due to larger volume to pressurize.

In track driving, feeding throttle in through a corner, it is actually less noticeable than when you just drop the pedal....still not the same as a naturally aspirated car, but easy to adjust to.

If you flash back to stock, there will be less lag, but also much less torque. I have a big intercooler and custom tune. I will happily tolerate a little lag for 475 ft-lb at the wheels.

[ShocknAwe]

Originally Posted by Coyner

Hi Folks,

I just bought my first 1M coupe which has a Lichtfield remap and a Millteck cat-back exhaust. Compared to a N/A car the throttle response is slow and lagging and mot linear .... slow to respond then huge boost. Things are much better with M button depressed but nothing like for example a Porsche 997.

I have never driven a stock car ..... is that just how these engines behave or does it sound like there might be something wrong?

Thanks folks!

The N54 has excellent tuning capability now. But it will never be as sharp as a NA engine. That said, I highly recommend you have the car custom tuned by someone with N54 experience. Wedge/twisted tuning/V8bait/Motiv all come to mind.

It's all in the tables that have been unlocked in the past 2-3y. Everything else is obsolete.

[Coyner]

Originally Posted by CarJunkie

In stock form, the DME targets 11psi which the turbos reach effortlessly, but it leaves a LOT of midrange torque on the table. Your tune is probably targeting 16-17 psi in the midrange and that will take more time for the turbos to spool up to, making the lag more noticeable. A larger intercooler also produces additional lag due to larger volume to pressurize.

In track driving, feeding throttle in through a corner, it is actually less noticeable than when you just drop the pedal....still not the same as a naturally aspirated car, but easy to adjust to.

If you flash back to stock, there will be less lag, but also much less torque. I have a big intercooler and custom tune. I will happily tolerate a little lag for 475 ft-lb at the wheels.

Thanks CarJunkie, that makes a lot of sense to me and matches my experience in road/track environment. What exactly is "DME"?

Thanks

[Coyner]

Originally Posted by ShocknAwe

The N54 has excellent tuning capability now. But it will never be as sharp as a NA engine. That said, I highly recommend you have the car custom tuned by someone with N54 experience. Wedge/twisted tuning/V8bait/Motiv all come to mind.

It's all in the tables that have been unlocked in the past 2-3y. Everything else is obsolete.

Thanks ShockanAwe. Its tuned by Lichftield in UK .... i'm pretty sure they know their stuff and specialise in 1M . Its probably just a matter of me resetting my expectations. My other car is a 997 C2S so it's probably not a fair comparison I'm making.

[CarJunkie]

Originally Posted by Coyner

Thanks CarJunkie, that makes a lot of sense to me and matches my experience in road/track environment. What exactly is "DME"?

Thanks

DME = digital motor electronics

BMW's proud adherence to what they have called their engine control computer and software since they pioneered the concept. Everyone else calls it the ECU.

[ShocknAwe]

Originally Posted by Coyner

Thanks ShockanAwe. Its tuned by Lichftield in UK .... i'm pretty sure they know their stuff and specialise in 1M . Its probably just a matter of me resetting my expectations. My other car is a 997 C2S so it's probably not a fair comparison I'm making.

What I'm suggesting is check with your tuner to make sure they're using the most up to date tables, AKA fully unlocked vanos etc. ALL the earlier tuning, see 2017 and before, wasn't.

I'm sure they know their stuff. I'd want to check though, otherwise you're leaving a lot in the table. No comment on the specialization in 1M.

[HP Autosport]

Originally Posted by Coyner

Hi Folks,

I just bought my first 1M coupe which has a Lichtfield remap and a Millteck cat-back exhaust. Compared to a N/A car the throttle response is slow and lagging and mot linear .... slow to respond then huge boost. Things are much better with M button depressed but nothing like for example a Porsche 997.

I have never driven a stock car ..... is that just how these engines behave or does it sound like there might be something wrong?

Thanks folks!

How is the throttle response in m mode?

[Coyner]

Originally Posted by HP Autosport

How is the throttle response in m mode?

It's pretty instant in M mode , snappy even but not linear. Motor responds very quickly to even small throttle openings but it's followed by a bit of an odd lag in build up , almost a hole, then followed by a huge surge.

With M mode turned off the throttle response is pretty dead a low openings , followed by the same dead feel and then a huge surge.

I know it's a turbo motor and can't be as finely responsive as NA but this just feels wrong. Its so not linear , almost as if it had a mind of its own , very tricky to drive both fast and smoothly.

I'm an experienced driver and have a few performance cars and find it hard to imagine my 1M is how BMW imagined the car.

[HP Autosport]

Originally Posted by Coyner

It's pretty instant in M mode , snappy even but not linear. Motor responds very quickly to even small throttle openings but it's followed by a bit of an odd lag in build up , almost a hole, then followed by a huge surge.

With M mode turned off the throttle response is pretty dead a low openings , followed by the same dead feel and then a huge surge.

I know it's a turbo motor and can't be as finely responsive as NA but this just feels wrong. Its so not linear , almost as if it had a mind of its own , very tricky to drive both fast and smoothly.

I'm an experienced driver and have a few performance cars and find it hard to imagine my 1M is how BMW imagined the car.

Maybe try a diff tune or flash it back to stock to see how it feels.

[CarJunkie]

^^^This.

What you describe is not normal, and is probably an artifact of a bad tune.

[Coyner]

Thanks guys .... yes culprit was a bad engine map!! It transpired my car had a overly aggressive Cobb map installed.

Today I got my hands on the Cobb device from the prev. owner and switched first back to stock map and car felt great instantly. Good throttle response and plenty of power.

Changed then to Stage I "Sport" map and car feels even better. Top end power is slightly down on before but everywhere else and especially throttle response and progressiveness of power built up are waaaay improved.

I'm now loving my 1M how lord BMW would have intended ! : )

Thanks for your input !

[CarJunkie]

Glad you got it sorted out!

If you want to run a tune, consider uninstalling Cobb and switch the MHD. The maps are much better and there continues to be development.

[PRTSB1M]

Originally Posted by Coyner

Changed then to Stage I "Sport" map and car feels even better. Top end power is slightly down on before

It seems most tunes taper boost after 6k rpm, to prolong turbo life. The top-end power is likely still higher than stock, but dropping from the midrange rpm's that are full or torque.