05-09-2020, 08:15 AM | #89 | |
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05-12-2020, 12:33 PM | #90 | |
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First, let me say thank you for this post and all the extensive data you have collected on this issue. Impressive, and well explained/thought out. Just bought a brand new M2C 6MT, and I am at 900 miles (still in break in period). This issue is DRIVING ME NUTS. I see a lot of very constructive back and forth here analyzing the results of these data logs, and as a lover of all things math related, I am totally nerding out on these data log plots. But to be honest, none of this is needed to understand what the OP is feeling: simply jump into the driver's seat of a M2C (or regular M2 apparently) with a manual transmission and give it a rip through the gears. To anyone that is a gear head and enjoys a spirited drive with a manual transmission and has any experience at all with other vehicles, it will be IMMEDIATELY apparent that something is "electronically" holding this car back in a major way when standing on the throttle after an upshift. No question about it. It is that bad and obvious guys. Again, I am still in the break in period so everything I describe is from the reference frame of a car being shifted under 5500 RPM. Let me try and paint a picture of what this feels like and how annoying it is, and I am not being hyperbolic here. Pick a gear, give it full throttle, choose a shift point, and execute a quick upshift to the next gear and immediately fully depress the throttle when the clutch is released. For full 0.5-1.0 seconds, NOTHING happens to accelerate this car. No data logs here, but the butt dyno says this car isn't even putting out 100 horsepower during the duration of this short period. Then, like a switch is flipped, power instantly comes back on strong and whatever boost you lost starts to quickly build back up. This effect happens every time, for the same duration, regardless of drive mode settings, regardless of whatever boost pressure you were at before shift, regardless of engine RPM, regardless of the speed of your shift. And it happens distinctly before any turbo lag effects kick in (which is minimal in my opinion). It makes you feel at first like you suck at driving a manual or something, its abrupt and not smooth, readily apparent to the driver or passenger alike. It feels like if you decided to drag race a car with 100 less HP and a driver with exactly equal shift speeds, you would lose solely because of this delay every shift. Most simply put, you slam the accelerator and the M2 says "NOPE......OK now go". Before ever reading this post or any others related, my immediate impression was that the car was cutting off fuel flow for this short duration for some reason, the power drop is that pronounced. Ever driven a car with a slipping clutch where you got no power to the wheels until the clutch hooked up? Similar to that but shorter than that and it feels distinctly digital, like power is totally off/on. I am not a professional driver, but consider myself a fairly skilled driver of manual transmission cars, especially BMWs. Over the years I have owned/still own a 2002, 4 different e36 m3s in various states of modification, a built s52 swapped e30, e46 330 zhp, etc. I have plenty of experience driving turbo cars, from super laggy, big-turbo older Porsches to small, fast spooling turbo cars like my wife's f30 328 and everything in between. I was a valet for years and have driven everything under the sun, at least around the block through the first couple gears. From my experience, this issue is totally unique to the M2/M2C (no experience in other s55 cars though). This ain't turbo lag. It is happening before and distinct from the turbo starting to spool back up. If anything this is causing more turbo lag than necessary because the car feels like it is not allowing the turbo to even begin spooling back up until that 1 second duration is finished, losing more boost all the while. Additionally, this issue is totally non-existent if cruising in any RPM, coming off the gas for a full second and then punching it. The car feels snappy and very responsive as it should, with only (IMO) minimal turbo lag. This is not DSC/traction control related. It feels like a protective measure that keeps the traction control from even kicking in. Moreover, the DSC/traction light has not flashed yellow even once, which is supposed to happen any time that system engages. I am actually starting to doubt whether this car even has the ability to chirp its tires when upshifting because of this issue! I sure can't make it, though its tough trying to stay below 5500 rpm while full throttle shifting from 1st to 2nd. But with this car's hp and torque figures, it should have no problem barking tires from 2nd to 3rd with a well executed shift. It can't. I highly doubt it is CDV related, as I have experienced that issue before in my other cars, and this feels MUCH worse/more pronounced to me. The wide open waste gate theory posted by the OP sounds very plausible to me, the subjective feeling of this issue mirrors exactly what I imagine would happen if the wastegate was just dumping all boost pressure for a second. I have never felt this in ANY other turbo car. What blows my mind is that in all the research I did on this car, and in all the videos I watched of reviews of the M2C and videos of pitting the M2C vs various other sports cars, not once did any driver mention this issue. The car got glowing reviews in literally every video I saw, and seemed to best every damn car they put it against on track. I did an enormous amount of due diligence before purchasing (my first new car ever). Not a single one of the talented and respected drivers that I watched flog this car around so much as mentioned it, even when pressed to try and find something negative about the car. I find this absolutely astonishing, as I find this issue so annoying that it takes most of the fun out of driving a manual transmission car!! If I was aware of this GLARING problem, it is bad enough that I would have second guessed buying the car without putting in some serious wheel time in one to decide if I could live with it. Its that annoying. The day I bought it, I let my best friend drive it immediately after we stepped out of his newly acquired '99 M Coupe. His first sentence within a quarter mile of driving my car (carefully and respectfully) was "whats up with that delay every time I shift?". It is that noticeable guys. I am also mind blown that this was not the very first thing addressed by tuners. I swear if you offered me a tune that fixed this problem but gave me 50 LESS horsepower I would be all over it. This issue has to be addressed, as it is the only major negative issue on what I would consider to otherwise be an absolute gem of a sports car. To the doubters, just drive a 6MT for 30 seconds and you will say "ohhhhh NOW I get it". |
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05-12-2020, 01:02 PM | #91 |
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forgot to mention
Also, I forgot to mention that I originally thought this lag may be a safety feature programmed in to reduce shock to the driveline during the break-in period. But after reading that any programming done to the car during the break-in service is just a myth, and obviously other people with more mileage are experiencing the same issue, I sadly don't think this is the case.
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05-12-2020, 02:38 PM | #92 | |
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Revving the car higher does seem to help, but as someone else mentioned, it is not a fix for the issue- only a mask. I personally find it very interesting that my M235i did not do this with a JB4 piggyback tune and downpipe. It’s possible the high flow of the downpipe also masked the issue... but that’s hard to believe as I could jam through the gears with violent power on that setup. I did not modify that car- the previous owner did- and I didn’t realize it until a year after buying it from a dealer (only had 5k miles on it and the previous owner bought a ZL1.) So it’s possible other hardware modifications were made that I’m unaware of and may have also affected the issue. |
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05-12-2020, 04:17 PM | #93 |
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@undergroundhead your thoughts mirror my own and I too believe that it should have been addressed before other tuning.
As I think I said before, I believe that the tuning community has largely been focussed on DCT, which is without a doubt quicker. They also tend to focus on pulls to red line in 3rd or 4th gear, and don't normally look at what happens after a shift. I can say that progress is being made with the tuner I'm working with. I'm basically starting with that tuner's base 91 AKI map, which though better than stock, has quite a bit less power than the 93 AKI OTS map that I was running with my other mods (WMI). But like you said, when there is no delay after shifting, the feeling is glorious and I'd take this map over the more powerful one any day of the week. Stay patient guys, I'm quietly confident that there will be a solution. Heck I'd take what I have now over stock or any other map I've tried so far. It's consistency that we're really trying to nail now.
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05-15-2020, 02:28 PM | #94 |
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just got break in service
So I just got my car back from break in service, I will do some driving this weekend and see what the difference is now that I can rev past 5,500 rpm. I will report back after trying shifts in all engine/traction modes.
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05-18-2020, 08:09 PM | #95 |
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I'm glad to have stumbled onto this thread. I have a 2014 m235i and have been disappointed with this behavior since I got the car years ago. Problem existed with stock tune to now bm3 stage 2 tune. I look forward to your results with your tuner. Add me to the list of folks willing to pay for a custom tune that eliminates this.
Food for thought.. 1. I've changed my driving behavior to try to accommodate this by getting on the gas sooner between shifts and sometimes may even be back on gas before releasing clutch fully. This helps. 2. Frequently when doing logs, I'll be in third gear at about 2500rpm, then floor it and experience this same lag. However if I roll into the throttle slowly then fast, I feel that the response is substantially better, so again I've altered my driving such that I'm always rolling into throttle for first 25 percent or so then floor it when I want to accelerate fastest. 3. I've read that dv upgrades help with this and the canned response is because it holds boost between shifts better, rather than dumping all the boost like the stock dv. Since the dv is electronically controlled, what I read between the lines is that tuning could make stock dv act like a upgraded dv. I would even go out on a limb and say that upgraded dvs are nothing more than a device that slows the input from dme to release boost.. 4. I've been waiting on ptf for a throttle sensitivity slider, but there hasn't been alot of word on this since this is another feature that would mostly benefit 6mt rather than dct. Anybody ever drive on mhd's linear throttle?
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05-19-2020, 02:35 PM | #96 |
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Nezil have you ever reset throttle adaptations during your testing. i am curious if that changes anything. i always notice the car drives much better after a reset. my car is a daily, so there might be some truth that it adapts to that lazy driving style.
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05-25-2020, 12:47 PM | #97 | |
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Yes, I think, though I'm not 100% sure, that when you flash a new map, adaptations are reset as part of the process. In any case, resetting adaptations is hardly a long term fix. On a more positive note though... the map I'm running now, and have been running for the last 8 days, has no loss of boost between 2nd and 3rd shifts about 90% of the time. No loss between 3rd and 4th shifts about 50% of the time as well. Whatever my tuner is doing is certainly working and I'm loving it. I'll try and post a log from my current map comparing the difference of a 2nd to 3rd shift to the BM3 OTS map (which is the same as stock in this regard).
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05-28-2020, 04:55 PM | #98 | |
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When I first started reading your research into all of this, what popped into my head was, "Is this part of the auto-revmatching?" Per BMW's documentation & statements, the ECU on 6MT cars does "magic" to help smooth performance during upshifts. My first thought was that this could be the root cause of this behavior. Since we know that revmatching is disabled (on an OG car like Nezil's) when you disable traction control entirely, I was wondering if your tests were being performed with ESP entirely off, or whether that has any change in behavior? It seems like some people have tested with it off and say they are still feeling the lag though... Also, have you tweaked anything else, like "Euro MDM" or other traction or DME-related stuff?
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05-28-2020, 06:35 PM | #99 | |
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05-28-2020, 10:41 PM | #100 | ||||
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To put this in to perspective, I was getting 0~60 times of just over 5 seconds in the past, and that was with the BM3 Stage 2 93 map. I'm now getting consistent 4.8s (= 4.45s with 1ft roll-out) times without trying that hard, and on the street not a sticky drag strip. The map I'm running at the moment is the starting point for a 91 octane tune from the tuner I'm working with, and is therefore quite a bit down on power from the OTS 93 map I was running previously as well. I think it's absolutely fair to say that the DME induced shift lag adds between 0.3 ~ 0.4s in a 0~60 run. Quote:
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06-05-2020, 02:09 AM | #101 |
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I drove a 6MT early production (I think 2014 but maybe 15) M4 in early 2018 and noticed the same thing about 400 metres from the dealership as the dealer is right next to a motorway onramp and of course I floored it up the onramp
I tried MDM straight away, then DSC off as I wondered if it was a traction control related issue and experienced no difference, then comfort, sport, sport+ for the throttle and again no difference. I didn't try adjusting my shift speed, I was simply shifting as fast as I could I did try hitting the throttle while in a gear though and noticed significantly less lag compared to when shifting up a gear and it was indeed quite frustrating. Ultimately it was a big enough issue to turn me away from ordering an M4 Comp 6MT and I ended up with my M6 (plus a few other things to be fair) I did ask about it a bit at the time and other M3/4 owners seemed to be aware of the issue, PLUS some 6MT M5 and M6 owners so this is also an issue on the S63TU engine which when compared to the S55 has significantly less lag. Unfortunately the 6MT S63TU combo was only available in the USA so I haven't had the chance to drive one of those but it is definitely on my to-do list when I make it to the USA. I have wondered if it is worse on the S63TU because of the less lag they have and the extra torque with that engine. tab comments? You're the first 6MT S63TU owner I could think of, mainly because yours is Tanzanite and perfect (apart from having too many doors :P)
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06-10-2020, 11:31 AM | #102 | |
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However, I noticed on NVM's website that they show a US location at: NVM USA 15-01 Pollit Drive Suite 8A Fair Lawn NJ 07410 Whilst there is no direct number on the NVM site for this address, a quick google shows that this is https://autocouturemotoring.com/ - might be worth a call to them Nezil. |
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06-16-2020, 02:45 PM | #103 |
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Tried to speak with NVM but not yet had a call back from their M2 expert.
Anyway, I finally found some time to sort out my BM3 logging and look further into this. I added the clutch switch to the monitored channels and this helped quite a bit. My observations are: 1) The lag is not related to a clutch depress; dipping the clutch and then re-engaging it gives 100% WGDC immediately; this confirms Nezil findings when he disconnected the clutch switch. 2) The WGDC lag is seen when changing up into gears 2, 3 and 4. 3) The WGDC lag is not seen when changing up into gear 5. Point 3 is the most significant, as it proves that the DME is introducing the lag following a change of input from the selected gear sensor. This sensor is located on top of the transmission: Looking into this further, on newtis there is actually quite a lot of detail, and it specifically lists the function that we find so annoying: "...the gear sensor is used for other functions such as gearshift speed control." I did ponder about disconnecting the sensor, but thought there would be issues/CELs and indeed there would be - the following are listed: "In the event of failure of the gear sensor, the following behaviour is to be expected: Fault code entry in the engine control unit or the electrical machine electronics Automatic engine start-stop function fails to operate Dynamic Stability Control (DSC) without function Reversing lamp fails to operate Gearshift speed control without function" Really only one of those is desirable, so I'm going to pass on disconnecting this sensor!!! The info of the gear sensor for 6MT can be found here: https://www.newtis.info/tisv2/a/en/f...sor/1VnYBEmDgY I do wonder (now that we know what the lag function is called) whether it could be disabled via coding (a slim chance I know, but hey I can dream!). The search for a fix continues..... |
06-16-2020, 03:34 PM | #104 |
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So what I’m getting here is- don’t bother shifting quickly, because the gearshift speed control is going to force you to slow down anyway. In fact, you may enjoy the experience more if you wait a second to get back on the gas and find yourself with full power, vs getting on it immediately only to find power missing for a half second.
We need the car to always think it’s in 5th gear when it’s in 2nd, 3rd, or 4th (maintains DSC but removes the gearshift speed control.) We need it to think it’s in actual gear for R (for backup lights) and 1st (auto start stop.) 6th sounds like it doesn’t matter either way. Theoretically you could put an intercept between the sensor and the ECU that manipulated the input signal to always show gears to the DME as R, 1, 5, 6. That, or you’d need to manipulate the DMEs calculation or output signal- but the further downstream you go, the more variables you have to impact... unless of course the DME outputs a very simple on/off signal back to the transmission. One thing you’d lose for sure by manipulating the input is auto rev matching. You car would be rev matching to 5th all the time. Last edited by Dasnub; 06-16-2020 at 04:16 PM.. |
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06-17-2020, 02:08 AM | #105 | |
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Looking in the electrical diagrams, the gear sensor is plugged into the DME. |
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06-17-2020, 03:25 AM | #106 |
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06-17-2020, 05:23 PM | #108 | |
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Pretty much sums up what we've been doing with this. Any help guiding us to turning off the gear shift speed control on the n55 6mt would be super appreciated! Thanks. |
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06-18-2020, 07:41 AM | #109 | |
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Since that post I've done a few more country drives and 2 track days and every fast shift (when I'm focussed) doesn't have the lag. I did experiment doing some slightly slower shifts and the lag often returned. It's probably fair to say those 'slower' shifts with the SSK may be around the quickest I could do with the oem shifter/linkages. I've just got a BM3 custom tune so hopefully things won't change for the worse. Something of interest, with my custom tune I had the Sport+ throttle map replaced with Sport so now have the 1 throttle setting for Sport/Sport+/DSC OFF and it works perfectly, haven't used MDM for quite a while as I didn't like the 'light switch' nature of Sport+ throttle. I'll probably get flamed but I also have re-match on for DSC OFF. |
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06-18-2020, 07:56 AM | #110 | |
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