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BMW 3-Series and 4-Series Forum (F30 / F32) | F30POST > Technical Forums > N20, N26, B46, B48 Turbo Engine / Drivetrain / Exhaust Modifications > Slipping Trans?
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      05-15-2020, 03:12 PM   #1
Steakpizza
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Hey guys,

So just recently got XHP on my N20. Everything was good, and I reflashed to mess with some LC settings. I noticed on the reflash that now when downshifting at low speeds, the revs jump up a bit then go back down.

For example, let's say I'm in 3rd at 2200RPM, when it shifts to 2nd the rpms go up to 23-2500rpms then goes back down.

I'm not too big on trans/clutch issues, but is this a sign? I've heard that the engine normally will do this, but I don't remember it like this. The gears would shift down smoothly before, now there's just this small blip up. I'm going to reflash to stock later tonight and mess with stuff, I just wanted some input. Thank you.

Video showing what's up.

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      05-15-2020, 03:21 PM   #2
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XHP adds more throttle blipping on downshifts which would likely be when you're seeing. Slip is usually noticed when on throttle rather than on slow down.
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      05-15-2020, 04:38 PM   #3
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I heard someone complaining in YouTube about not noticable blip...so XHP complied with the request...now there are strong blip
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      05-15-2020, 06:11 PM   #4
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Sounds like it's doing some rev-matching, but you can post a video for us to confirm if you're worried about it. Probably normal though.
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      05-15-2020, 06:25 PM   #5
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Quote:
Originally Posted by rjd_F30 View Post
Sounds like it's doing some rev-matching, but you can post a video for us to confirm if you're worried about it. Probably normal though.
After reading around thats what it seemed like. It was weird because the first flash I did, I didn't have the matching, and I never had it on stock afaik. I changed XHPs Torque Limit option from AWD to Standard , and changed some LC settings, and had the matching occur. I then switched from Standard back to AWD and the matching was happening. I was just confused because it wasn't happening on the initial flash. I'll try and grab a vid for you all. Thanks
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      05-15-2020, 09:23 PM   #6
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Quote:
Originally Posted by rjd_F30 View Post
Sounds like it's doing some rev-matching, but you can post a video for us to confirm if you're worried about it. Probably normal though.




There's a video for you bro. You can see the revs jump when I downshift. It's the same if I come to a stop, or if I brake and come to a stop. It also doesn't matter what speed I'm going, it's similar if I'm going 10-15mph and downshift or if I'm cruising at 60 and start to downshift. In Comfort this happens slightly. Would be good to know if it's a result of XHP as opposed to something else. Zero issues when up shifting or driving normal.
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      05-15-2020, 10:31 PM   #7
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Quote:
Originally Posted by Steakpizza View Post



There's a video for you bro. You can see the revs jump when I downshift. It's the same if I come to a stop, or if I brake and come to a stop. It also doesn't matter what speed I'm going, it's similar if I'm going 10-15mph and downshift or if I'm cruising at 60 and start to downshift. In Comfort this happens slightly. Would be good to know if it's a result of XHP as opposed to something else. Zero issues when up shifting or driving normal.
Yep, that's definitely normal rev-matching as a result of xHP, nothing to worry about My car does the same thing with the bootmod3 trans tune.
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      05-15-2020, 10:31 PM   #8
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Quote:
Originally Posted by rjd_F30 View Post
Quote:
Originally Posted by Steakpizza View Post



There's a video for you bro. You can see the revs jump when I downshift. It's the same if I come to a stop, or if I brake and come to a stop. It also doesn't matter what speed I'm going, it's similar if I'm going 10-15mph and downshift or if I'm cruising at 60 and start to downshift. In Comfort this happens slightly. Would be good to know if it's a result of XHP as opposed to something else. Zero issues when up shifting or driving normal.
Yep, that's definitely normal rev-matching as a result of xHP, nothing to worry about My car does the same thing with the bootmod3 trans tune.
Much love bro! Thought I was going crazy ahaha
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      05-16-2020, 09:06 AM   #9
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I thought all automatics rev matched when downshifting, tuned or not? All my cars do that, even my G20 330i. Not sure what I’m missing here.
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      05-16-2020, 09:07 AM   #10
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Quote:
Originally Posted by VipinLJ View Post
I thought all automatics rev matched when downshifting, tuned or not? All my cars do that, even my G20 330i. Not sure what I'm missing here.
So that's the thing, with the XHP flash it's extremely pronounced, and it was a bit much so I wanted to double check.
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      05-16-2020, 04:00 PM   #11
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Quote:
Originally Posted by VipinLJ View Post
I thought all automatics rev matched when downshifting, tuned or not? All my cars do that, even my G20 330i. Not sure what Im missing here.
My car sorta did it stock, but it's far more pronounced after doing the transmission tune.
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      05-16-2020, 08:01 PM   #12
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Quote:
Originally Posted by Steakpizza View Post
So that's the thing, with the XHP flash it's extremely pronounced, and it was a bit much so I wanted to double check.
Quote:
Originally Posted by rjd_F30 View Post
My car sorta did it stock, but it's far more pronounced after doing the transmission tune.
Ah gotcha. In my car, it's more noticeable in sport plus compared to the other modes. The tune probably makes it even more noticeable.
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      05-18-2020, 06:52 AM   #13
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Lol wow
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