[Andy198712]

Hi,

I'm getting an odd limiter at the minute.

The car had a custom remap on it, its an N57 325d 204 bhp, now up to 290bhp and 577nm, drives super smooth and clean.

apart from one down hill stretch of road just as i leave work, as i would hit 60mph at about 3\4 throttle it would hit a hard limit, jolt the car kinda hard, not just a gentle thing.

wouldn't do it up hill or flat ect, just on gentle down hill if it passed 3krpm in 3rd (auto box)

So took it back he adjusted the map a bit and all seemed well, said if it does it again then try the same route with traction off and see if that changes thing (trying to narrow it down)

Now for ages it wouldn't do it anymore, but then the other day it did it at 50mph about mid to high (not full) throttle on fairly flat ground this time.....

its rare but its a hard cut, feels brutal, like someone punching the brake pedal for a split section.



No limp mode, no codes..... at all.

Cheers
Andy

[JuiceQuadre]

does it feel like it does it when switching gears? or what happens after the jolt? the rpms just keep rising like nothing happened?

something similar happened to me maybe 3 times of those 2years i own the car.. it felt like either the transmission or misfire of sorts.. but it doesnt come back so i dont know

[335stoner]

i don't think you would hit a limiter like that going down a hill? going down a hill would allow the car to use less power.

hitting a limiter going up a hill would seem more likely..

FWIW i have zero experience with this issue

[Andy198712]

Originally Posted by 335stoner

i don't think you would hit a limiter like that going down a hill? going down a hill would allow the car to use less power.

hitting a limiter going up a hill would seem more likely..

FWIW i have zero experience with this issue

Yeah thats the funny thing, its not at max load....

[Andy198712]

Originally Posted by JuiceQuadre

does it feel like it does it when switching gears? or what happens after the jolt? the rpms just keep rising like nothing happened?

something similar happened to me maybe 3 times of those 2years i own the car.. it felt like either the transmission or misfire of sorts.. but it doesnt come back so i dont know

So all this happens in the space of a second or two, you get the hard jolt, and i noticed the revs floated for a second or so, maybe raised 100-200 rpm then dropped off (as i take my foot off the pedal when it happens)

then when i get back on the throttle all is normal, no limp mode, no warning lights on the dash and no codes left.

it must be the engine saying "no" ? as if the gearbox free wheeled then the revs would rev line (think manual car, driving and putting in the clutch under power) it doesn't do that....

feels like a hard backfire of sorts? but no noise or dash lights or codes.... very hard to replicate, when i took it back to the place that tuned it, i gave the exact situations and he did manage to get it to do it which was lucky for me.

They adjusted the map (they are a satellite for the tuner, but have a BMW race car so know there stuff and the map is buttery smooth)
and he reset the gearbox adaptations and the DTC longitudinal and lateral adaptations too and said if it happens again try doing that same stretch with traction off to rule that out.

strange one!


First time it happened i though boost spike or pipe blow of or engine shit its self lol

after the adjustments that he made it didn't do it anymore in that situation, now it does it a very certain times on a flat bit of road, i'm had it happen once in a month or lots of spirited driving ect

just wondering if anyone had this but google pulled a blank, couple of 123d's remapped said something similar but like 1 post out the whole of google!



just to add the car is well serviced, just did the gearbox oil too (just fluid and will do this again a few times to help flush the old stuff out then do filter too, costly but....)

only thing i noticed is the fuel filter has a dent in it from a impact which i will change but i cant see that being an issue, just a minor thing i noticed. and a restriction in flow would defiantly throw a code and it was fine before being remapped.

[Andy198712]

only other thought i had was invest in the xhp and have the box remapped but not even sure its that.... and there are other cars out there running more power

[335stoner]

maybe its some type of fuel cut off? (pulling stuff from my butt)

is the car still on the stock trans tune?

[335stoner]

just saw your post... lol (you posted as i was typing)

[335stoner]

Originally Posted by Andy198712

just to add the car is well serviced, just did the gearbox oil too (just fluid and will do this again a few times to help flush the old stuff out then do filter too, costly but....)

check your trans fluid level!

had this happen on a truck of mine (non bmw)

The trans had a small leak, but would shift fine all day long. get it in the right situation and floor it the truck would downshift and start to go then heading towards the top of the RPM the truck would buck (JUST LIKE YOU SAID) let off and everything was fine.

my issue was when it would downshift it trans demanded more fluid. as it pushed harder it ran out of trans fluid in the pan and would suck some air and jolt the truck..

when i added fluid the truck acted 100% normal until i lost the fluid again.

[Nadir Point]

Originally Posted by Andy198712

What does a torque limiter feel like?

It's hard to tell, because you feel it every time you mash the go pedal, more so in the lower gears. It's the "Poor Throttle Response" complaint people unfamiliar with driving diesels talk about. The ECU limits torque (fuel) dynamically all the time to protect hard parts downstream of the crankshaft.

[Andy198712]

Originally Posted by 335stoner

check your trans fluid level!

had this happen on a truck of mine (non bmw)

The trans had a small leak, but would shift fine all day long. get it in the right situation and floor it the truck would downshift and start to go then heading towards the top of the RPM the truck would buck (JUST LIKE YOU SAID) let off and everything was fine.

my issue was when it would downshift it trans demanded more fluid. as it pushed harder it ran out of trans fluid in the pan and would suck some air and jolt the truck..

when i added fluid the truck acted 100% normal until i lost the fluid again.

Happened before and after the trans fluid change and deffo correct now, good idea though!

and yh stock trans tune great minds and all that

[Andy198712]

Originally Posted by Nadir Point

It's hard to tell, because you feel it every time you mash the go pedal, more so in the lower gears. It's the "Poor Throttle Response" complaint people unfamiliar with driving diesels talk about. The ECU limits torque (fuel) dynamically all the time to protect hard parts downstream of the crankshaft.

so its gentle? not like a hard limit you'd say?

i always thought that was traction control pulling power, well i know it is sometimes as the traction light flashes at me and it pulls harder with that off or lights up the tyres

[Nadir Point]

"Torque Management" is the term for what I am describing. The only "hard limit" is a free-spinning engine at WOT de-fueling by program logic at some combination of plausible values.

[Andy198712]

Originally Posted by Nadir Point

"Torque Management" is the term for what I am describing. The only "hard limit" is a free-spinning engine at WOT de-fueling by program logic at some combination of plausible values.

Thank you,

Such as the Red line? Which isn’t something I can hit on my stock auto box but normally diesels seem to have soft hitting Rev limit....
This is about 2.5-3k rpm when it occasionally occurs but then the car can sing full throttle to the redline in sport no issues....

Thanks for helping me get some ideas together guys

[3wis3m3n]

Originally Posted by Nadir Point

It's hard to tell, because you feel it every time you mash the go pedal, more so in the lower gears. It's the "Poor Throttle Response" complaint people unfamiliar with driving diesels talk about. The ECU limits torque (fuel) dynamically all the time to protect hard parts downstream of the crankshaft.

Sprint booster help eliminate that ‘poor throttle response’ for people that are unfamiliar with driving diesels. I for one have tried it and I was shocked to find out that those things actually freakin works..
Most people, the lazy ones don’t have time waiting for the throttle response, they want it right away as soon as they touch the pedal. If you are one of those people,
I’m guessing you will love sprint booster more than porn
Heck you probably will think that your car is actually faster now with it ...
(It’s not)

[mjez]

Andy198712
Have you ever resolved your issue?
I have exact same thing happening to my car after I got it tuned, except in my case it happens at lower speeds and a lot, several times a day. It either "jolts" or I get Limp Home message on I-Drive and than car wont exceed 12mph. I am curious as to what you did to sort it out.

[Andy198712]

it was remapped again by the same tuner and it stopped.... not quite sure what he did though tbh? but i doesn't do it any more, it was a mapping issue basically but i'm unsure if it was ECU or TCU related, sorry