E86 Z4M weird Deceleration

ctdriver86 · 04-10-2023, 11:32 AM

I'm hoping this is where it's appropriately posted. I'm getting a random weird deceleration when I down shift the car in gear. It feels like it's decelerating much quicker than normal, as if it has a regen mode on. LOL. This happens only randomly. And no, I'm not pressing the brake pedal but it feels like it is.

Does anyone have this issue and know why it's happening?

3002 tii · 04-10-2023, 05:22 PM

Not trying to be sarcastic but have you driven manual for a while? Sounds like you’re describing normal engine braking. Do you rev match on down shifts?

ctdriver86 · 04-10-2023, 06:46 PM

Lol, yea I do. I have a 6 speed e46 m3 too, a manual e30 and a 5 speed 71 2002 that have both been sold. I also do track days and canyon drives. Pretty confident in my ability to drive manual. Which is why I found it odd and it's random. I can't seem to replicate it exactly except when I'm driving at a reasonable pace, then downshifting (heal toe) to the lower gear, it happens whether I'm lightly pressing the brake or not. Then I do it again, and it doesn't do it. It's weird, I don't have this issue with the e46 m3 or any other car. The only thing different I can see that this car has from my e46 m3 and other cars is it has that stop feature that prevents you from rolling back on a hill. But I'm not sure how that system works yet. I should look it up, lol

XMetal · 04-10-2023, 11:25 PM

If it happens only after a heel/toe downshift, then you may have a sticking caliper? Does it happen when you just revmatch downshift without touching the brake?

3002 tii · 04-11-2023, 10:25 PM

Quote:

Originally Posted by ctdriver86

Lol, yea I do. I have a 6 speed e46 m3 too, a manual e30 and a 5 speed 71 2002 that have both been sold. I also do track days and canyon drives. Pretty confident in my ability to drive manual. Which is why I found it odd and it's random. I can't seem to replicate it exactly except when I'm driving at a reasonable pace, then downshifting (heal toe) to the lower gear, it happens whether I'm lightly pressing the brake or not. Then I do it again, and it doesn't do it. It's weird, I don't have this issue with the e46 m3 or any other car. The only thing different I can see that this car has from my e46 m3 and other cars is it has that stop feature that prevents you from rolling back on a hill. But I'm not sure how that system works yet. I should look it up, lol

Hill or park assist (whatever it’s called) only works when you’re coming off brakes from neutral. Does this happen in all gears? When you left off the gas, does the car track straight? I agree with post above, could be seized caliper.

wdb · 04-12-2023, 02:20 PM

It could be something with the engine computer. It might be holding the throttle open slightly at times and not at others. Z4M is DBW.

04-10-2023, 11:32 AM	#1
ctdriver86 Private 14 Rep 64 Posts Drives: e46 m3 Join Date: Apr 2017 Location: Torrance iTrader: (1)	E86 Z4M weird Deceleration I'm hoping this is where it's appropriately posted. I'm getting a random weird deceleration when I down shift the car in gear. It feels like it's decelerating much quicker than normal, as if it has a regen mode on. LOL. This happens only randomly. And no, I'm not pressing the brake pedal but it feels like it is. Does anyone have this issue and know why it's happening?
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04-10-2023, 05:22 PM	#2
3002 tii Lieutenant General 2286 Rep 12,565 Posts Drives: Z4 M, X5, GX460 Join Date: Apr 2008 Location: CT iTrader: (99) Garage List F15 X5 xDrive35i [8.75] E86 Z4 M [10.00] F10 550i (Retired) [9.17] F25 X3 xDrive35i (R ... [9.43] E82 135is (Retired) [9.50] E85 Z4 M (Retired) [9.41] E90 328i xDrive (Re ... [9.25] E86 Z4 3.0si (Retired) [9.24]	Not trying to be sarcastic but have you driven manual for a while? Sounds like you’re describing normal engine braking. Do you rev match on down shifts? __________________ Follow for latest mods
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04-10-2023, 06:46 PM	#3
ctdriver86 Private 14 Rep 64 Posts Drives: e46 m3 Join Date: Apr 2017 Location: Torrance iTrader: (1)	Lol, yea I do. I have a 6 speed e46 m3 too, a manual e30 and a 5 speed 71 2002 that have both been sold. I also do track days and canyon drives. Pretty confident in my ability to drive manual. Which is why I found it odd and it's random. I can't seem to replicate it exactly except when I'm driving at a reasonable pace, then downshifting (heal toe) to the lower gear, it happens whether I'm lightly pressing the brake or not. Then I do it again, and it doesn't do it. It's weird, I don't have this issue with the e46 m3 or any other car. The only thing different I can see that this car has from my e46 m3 and other cars is it has that stop feature that prevents you from rolling back on a hill. But I'm not sure how that system works yet. I should look it up, lol
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04-10-2023, 11:25 PM	#4
XMetal Colonel 1136 Rep 2,867 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	If it happens only after a heel/toe downshift, then you may have a sticking caliper? Does it happen when you just revmatch downshift without touching the brake? __________________
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04-12-2023, 02:20 PM	#6
wdb dances with roads 4732 Rep 4,096 Posts Drives: '07 E86, '02 996, '95 Seven Join Date: Jul 2015 Location: the perimeter iTrader: (4)	It could be something with the engine computer. It might be holding the throttle open slightly at times and not at others. Z4M is DBW.
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