09-29-2016, 04:21 PM | #1 |
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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. |
09-29-2016, 07:38 PM | #2 |
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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 | |
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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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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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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 | |
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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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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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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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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. It’s 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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07-26-2020, 02:20 AM | #16 |
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This is the only thread I could find that sounds similar, but my car has done the same thing a few times as well. If I get on it maybe 75-95% throttle and shift around 5,000-6,000 and then let off the gas, the RPM’s will instantly shoot up and the engine will rev until I manually upshift. 2015 M4 running BM3 stage 1 and THOR GTS dct tune. What could this be? It only has happened randomly but otherwise the car drives fine and strong.
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