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      09-29-2016, 04:21 PM   #1
Daxos
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Weird DCT experience

Let me start off with the specs of my car as it isn't stock.

2016 M4 DCT, VF Stage 2 tune (updated file), TCU tune, Akrapovic downpipes, midpipes and exhaust, AFE filters, charcoal filter delete.

I've had my car modded for about 2 months now without encountering any problems. This week, twice, I encountered very weird DCT behavior and I'm not sure if it's related to the weather finally getting colder, my driving, or if something is wrong with my car.

After about a 25 mile drive home I stepped on the gas in 4th gear in Sport mode in S2. Not full on the throttle and I didn't redline it but shifted around 5k rpm, but when I did shift into 5th the engine RPM's didn't change for a moment and it felt like the engine actually revved up instead of dropping revs instantaneously as it always does. I didn't think much of it until it happened a second time when I started becoming worried.

I haven't actively tried to reproduce this issue yet and I'm trying to figure out if it's something I did that caused it, but I haven't experienced this before and it doesn't seem right. Is that a sign of a slipping DCT clutch?

Any help would be appreciated.
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      09-29-2016, 07:38 PM   #2
Frank M3 NJ
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most likely a tune issue. I would focus on that being the issue, but see if it happens more often if it does remove the tune and see if it still does if not you know the source of the problem. If you have a reputable shop around you that tunes cars bring it to him and get him to data log it for a day or two and see if he notices anything strange. The problem with turbo cars and cars now days in general is the computer systems are highly complex and also the main heart of your car. Its a double edged sword when you start messing with them the benefits are great but sometimes stuff like this happens and can throw your whole car out of whack. good luck and i will watch for this in my car now since i have a DCT too.
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      09-29-2016, 07:54 PM   #3
Daxos
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Quote:
Originally Posted by Huxtable87 View Post
most likely a tune issue. I would focus on that being the issue, but see if it happens more often if it does remove the tune and see if it still does if not you know the source of the problem. If you have a reputable shop around you that tunes cars bring it to him and get him to data log it for a day or two and see if he notices anything strange. The problem with turbo cars and cars now days in general is the computer systems are highly complex and also the main heart of your car. Its a double edged sword when you start messing with them the benefits are great but sometimes stuff like this happens and can throw your whole car out of whack. good luck and i will watch for this in my car now since i have a DCT too.
Thank you for your reply. It have not experienced this issue until I updated my existing VF Engineering Stage 2 file, but I would not blame it on VF since temperatures changed, and I don't have that much experience with the DCT so I'm looking for some opinions first.

I'm not sure about giving my car away for a couple of days for data logging, but maybe I have to do that. Other than than those two hiccups the car acts just fine, but I'm obviously concerned about what happened so maybe I have to give it a try and have it datalogged. Thank you for your analysis and recommendations.

Last edited by Daxos; 09-29-2016 at 07:57 PM.. Reason: typo
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      09-29-2016, 09:47 PM   #4
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I will drive my car tomorrow and see what happens. I will report back.
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      09-30-2016, 09:36 AM   #5
Daxos
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I didn't get a chance to take the car out today but will do so over the weekend.
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      10-04-2016, 10:25 AM   #6
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I haven't been able to reproduce the issue after quite a bit of driving over the past couple of days. I'm going to keep an eye out for the issue but I'm not too concerned about it anymore.
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      11-01-2016, 08:49 AM   #7
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Unfortunately I have encountered the issue again this morning on my way to work. It was a little below 70 degrees, I had driven the car for about 4 miles or so and the oil temperature was approaching 220 degrees F which is normal for my car. I was in 5th gear accelerating enthusiastically but not flooring it.

I reached around 4k RPM and all of the sudden the engine just started revving higher but there was a complete loss of power, as if the car wasn't in gear. I immediately got of the gas (not sure how high the revs got but I doubt higher than 6k) and mildly stepped on it again and the power was there again.

I continued my drive and even went WOT through third gear once this morning without any further issues but this sudden complete loss of power does concern me.

As mentioned before, my mods are in the original post. Is this the sign of a slipping DCT clutch?

Any insight would be appreciated.
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      11-01-2016, 11:12 PM   #8
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Quote:
Originally Posted by Daxos View Post
Unfortunately I have encountered the issue again this morning on my way to work. It was a little below 70 degrees, I had driven the car for about 4 miles or so and the oil temperature was approaching 220 degrees F which is normal for my car. I was in 5th gear accelerating enthusiastically but not flooring it.

I reached around 4k RPM and all of the sudden the engine just started revving higher but there was a complete loss of power, as if the car wasn't in gear. I immediately got of the gas (not sure how high the revs got but I doubt higher than 6k) and mildly stepped on it again and the power was there again.
When you had your loss of power was it while in gear or while changing gears?

clutch pack slippage should only occur during a gear change, not while accelerating. Once the gear is engaged it should remain engaged unless there is a failure in one of the cogs, or its disengaging the gear as a fail safe.
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      11-01-2016, 11:22 PM   #9
Daxos
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Quote:
Originally Posted by 4everkidd View Post
When you had your loss of power was it while in gear or while changing gears?

clutch pack slippage should only occur during a gear change, not while accelerating. Once the gear is engaged it should remain engaged unless there is a failure in one of the cogs, or its disengaging the gear as a fail safe.
It was definitely while in gear. I was in 5th gear, and the revs just raised as if I wasn't in gear (from experience of driving manual cars).
Basically the REVS just went up but there was a complete loss of power.
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      11-01-2016, 11:30 PM   #10
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Quote:
Originally Posted by Daxos View Post
It was definitely while in gear. I was in 5th gear, and the revs just raised as if I wasn't in gear (from experience of driving manual cars).
Basically the REVS just went up but there was a complete loss of power.
That high in the rev range your DCT clutch should not slip... sounds like its disengaging or slipping out of gear.

Check for an update on the DCT/Trans flash; sorry to say but that doesn't sound good.
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      11-02-2016, 07:45 PM   #11
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Quote:
Originally Posted by 4everkidd View Post
That high in the rev range your DCT clutch should not slip... sounds like its disengaging or slipping out of gear.

Check for an update on the DCT/Trans flash; sorry to say but that doesn't sound good.
I have ISTA update 58.1 I believe. Is this different from the DCT/Transmission?

I am planning on getting charge pipes, a heat exchanger and new and wider tires put on by my shop, I'll ask them to reset the TCU learning curve since I have the VF ECU stage 2 and TCU tune. Maybe that will address things.

I'm just confused why it happens so rarely. Almost like as if it was temperature related as the temperatures in Kansas have been dropping into the low 60's as highs as of lately with 40's being the norm on my drive to work when this issue last occurred.

Last edited by Daxos; 11-02-2016 at 07:47 PM.. Reason: addendum
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      11-15-2016, 11:24 PM   #12
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I had my car my shop today for some work such as charge pipes and a new heat exchanger and also had the TCU and clutch adaptations reset. I did a few pulls from 3rd to 5th up to 7k rpm and did not encounter the issue again, so maybe it was as issue of the TCU relearning.

I will report back on my encounters over the few weeks before it gets too cold to drive in Kansas/Missouri.
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      02-03-2017, 12:52 PM   #13
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Another update - Everything seemed fine after a TCU reset. After about a dozen drives with several WOT pulls up through 5th there weren't any issues. Until today. 30 degrees F outside. I've drive for about 20 minutes (all the temps should have been fine by then) and did a WOT pull in 4th. Short before 6k RPM it felt like the car went out of gear again. I was able to reproduce the issue 10 minutes later once more. Again, 4th gear WOT right around 6k RPM.

Has anyone else experienced anything of the sort before? Is this the sign of a slipping clutch in DCT cars?
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      02-24-2020, 04:52 AM   #14
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Quote:
Originally Posted by Daxos View Post
Another update - Everything seemed fine after a TCU reset. After about a dozen drives with several WOT pulls up through 5th there weren't any issues. Until today. 30 degrees F outside. I've drive for about 20 minutes (all the temps should have been fine by then) and did a WOT pull in 4th. Short before 6k RPM it felt like the car went out of gear again. I was able to reproduce the issue 10 minutes later once more. Again, 4th gear WOT right around 6k RPM.

Has anyone else experienced anything of the sort before? Is this the sign of a slipping clutch in DCT cars?
2015 F80 M3 done 76,000KM. I flashed my car with Alpine MSS tune stage 2 which is pretty conservative about 4 months ago. Once I was getting onto the highway mid afternoon and I was Slowly revving out the engine and doing about 80Kph, I did about 60% throttle for literally 2 seconds and shifted up so RPMS were about 5.5K if that and the rev counter literally shot instantly upwards to like 6.5Rpms and it sounded like a money shift in a manual car and there was no power, I let off the gas instantly and upshifted all the way to 7 and car ran normal. Did a few downshifts and pulls car was fine.

Flashed back to stock couple days ago and today I was going slower through traffic which was moving and taking an off ramp in 3rd gear I did the same thing accelerated 60% and before it even rolled into full boost I upshifted into 4th but it made the weird noise like engine was free revving and the RPM needle shot forwards again roughly 1500rpms higher.

Itís as if the car is not clearing into the next gear and staying in the same gear. At first I thought it was clutch since I had tune but now it happened on stock everything wondering if it is the clutches.

Would clutches be covered under factory warranty because My warranty ends 28th Feb...
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      02-24-2020, 11:51 AM   #15
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No more dct in next model of M4 <3
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