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BMW 3-Series (E90 E92) Forum
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Light Throttle Hesitation
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08-08-2017, 02:53 AM | #45 | |
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The throttle closure at 6400rpm is your shift, this throttle closure at 3100rpm is at the beginning of the pull and may be part of the hesitation if it's in that area: http://www.datazap.me/u/hoper/catles...-62&mark=41-44 Torque request is mapped to the pedal, which is how you wind up with a wide open throttle plate/full load request at less than full pedal. Try the stock throttle option (modifies the torque request per pedal position table). Sport mode will also change to a different torque request table, which generally has more torque requested at lighter pedal. I am not sure if the linear/stock pedal options on MHD change both tables or just non-Sport. |
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08-08-2017, 06:53 AM | #46 | ||
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08-08-2017, 11:57 PM | #47 |
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I am at sea level and switched from linear throttle back to stock throttle. No luck. No boost leak, i'm at 21 psi at 6k rpm with 48%wgdc. Going to check on plugs and injectors again and if all looks good i'll swap the hpfp again
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08-12-2017, 02:49 PM | #48 |
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Drives: 2008 335i Coupe 6-speed
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Suck to hear others are having this issue. I was as well until I recently switched to NGK 59770 plugs..it seems to have helped almost eliminate the hesitation. Mine was happening at 2900-3100RPM and would get worse as the car warmed up. I haven't changed anything else in my car besides the plugs.
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'08 E92 335i 6MT Coupe SGM | MHD Stage 2 93oct | Cp-E CP | AA BOV | DCI | VRSF DP | VRSF 5" Stepped FMIC | Apex Arc-8 | Cyba Air Scoops | Failing HPFP....
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08-13-2017, 11:13 AM | #49 |
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This is a log of the issue. You can see it until i give it a little more throttle and its gone
http://www.datazap.me/u/bartbes/fluc...og=0&data=3-21 |
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08-13-2017, 12:09 PM | #50 | |
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335i e92 TPC 19Ts
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08-13-2017, 04:41 PM | #52 | |
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08-14-2017, 01:21 AM | #53 |
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+1, nice job. The issue occurs at the higher accelerator position/load too, but definitely to a less noticeable extent.
http://www.datazap.me/u/bartbes/fluc...15-17-18-21-25 |
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08-14-2017, 09:54 AM | #54 |
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What do you guys think of this?
not present present These were taken in the same situation, with only a few minutes in between Edit. In my case it is NOT rpm related. I can make the same present and not present logs on any rpm between 1400 and lets say 3500. How higher rpm goes the faster it oscilates up and down, shorter sinus. Last edited by bartbes; 08-14-2017 at 11:08 AM.. |
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08-14-2017, 10:31 AM | #55 | |
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08-14-2017, 01:48 PM | #57 | |
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2011 335is DCT BQ Tuning / BMS CAI / VRSF kittyless DP's / Synapse BOV and charge pipe / 7" VRSF Race FMIC / Walbro 535 and 450 on BMP4 / E90 tune / Diff Brace / PR Coils / Relocation Inlets / DAW Stage3+ Turbos / MMP port injection / xHP Stage 3 / FPR and -6 fuel lines
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08-14-2017, 03:22 PM | #58 |
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Hey guys, just chiming in as I just found this thread. I have a 2007 335, 6 speed. I'm getting WILD oscillations on the highway at very light throttle, anything over 2950 rpm. If I'm holding a constant speed anything over 80, the car starts bucking like crazy. Oscillating steadily, unable to just keep a constant steady throttle. Also, on startup, sometimes it oscillated and stumbles, and it'll diedown to 3-400 rpm, and shoot back up to 1000ish, and then stumble back down to the 300ish. there have been a few instances where coming to a stop, pushing the clutch in, the car has outright stalled out on me. I've done LOTS to the car to try to alleviate this. Please note, I do have failing turbos. My wastegates rattle, and while the car will build boost, the boost wavers until it springs the code. I would like to solve the stumbling/oscillation before I spring the money for new turbos/tune/intake/DP all at once. Another note- like mentioned before, it I'm going for boost or give the car any kind of real throttle input at all, the oscillations immediately go away, and it runs smooth as can be.
I'll try to list what I've done off the top of my head (all done by Matt at ZNM, he's been a huge help to me. Index 12 injectors, coded in. All 6 mosfets replaced, 2 were found to be bad. Might as well do them all while I've got Matt in there. Checked o2 sensors, and tmap- they all respond wonderfully when being monitored in real time Searched for boost leaks, found a cracked VC, replaced. No other boost leaks found with smoke test. New battery installed this weekend, old one crapped out and was giving me issues for months. We think my Low pressure fuel sensor is bad, Matt is sure it is. Thinks it wont affect what's happening, since he has no reason to believe that the lpfp isnt giving appropriate pressure. it's pegged at around 107psi IIRC, and doesnt change much. I told him today that I'd like to go ahead and replace it anyway, just to get a working sensor in there. In theory, it could be the sensor/ the lpfp crapping out, from the strictly low demand situations my oscillations and stumbling occur at. Idk, just my brain trying to comprehend the money I've thrown at this problem while it undoubtedly persists. And I'm hesitant to work on the 335... my 330 drift car I'll drop the transmission again without hesitation, but the tech in the 335i scares the piss out of me. Just my 2 cents, let me know if there's anything blatantly I'm missing anything, and my manual car behaving the same means it might not be your tq converters contributing to the issues. |
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08-14-2017, 03:44 PM | #59 |
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Just because it happens at that RPM at other times, doesn't mean it doesn't matter. Whenever it does occur, does a little more or less pedal make it stop?
Yes, AFRs are messed up when the surging occurs. The double-helix pattern of the AFR in the first log is correct. The issue is easily correctable via tune. |
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08-15-2017, 12:41 AM | #60 |
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More throttle makes it stop, less doesnt until im completely off.
According to nu tuner, it isnt in the tune unfortunatly, but i still hope so it is. If it is in the tune could jou explain why one moment it occures, the next minute it is gone, then it is there but less pronounced, and the next day it is back again? All in random order btw |
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08-15-2017, 02:43 AM | #61 | |
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Much goes into the DME calculations and almost anything can trigger it here and there if it’s right on the edge, but more likely, it's the simple fact that minute differences in pedal position could mean anything from a 20-70% request in the cruise range on the stock tables. |
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08-15-2017, 06:02 AM | #62 |
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Was going to elaborate some...
The log i saw, showed a 5% increase in pedal w a 20 point incrs in load. I will try to post my pedal tables from tunerpro. But that seems a litl high, since a 20 pt increase could be 10-15%. Guess what happens is when the load tables are increased perhpas the % increases get higher...
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335i e92 TPC 19Ts
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08-15-2017, 06:44 AM | #63 |
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Checking in with similar sputter/hesitation at only cruise and light constant load. Mhd e40 flash.
New injectors and plugs, i know i have o2 issues, suspect o2s. |
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08-15-2017, 12:34 PM | #64 |
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This goes beyond my knowledge sorry guys.
I could flash it back to stock to check if it solves the problem, cant hurt when i baby the car right? (It has stage 2 turbo's) |
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08-15-2017, 01:41 PM | #65 |
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That stock table is the problem. By flashing back to stock, it may only alleviate it due to the lower output at the same requests. Your tuner should be able to knock that change out in a few minutes. If the map isn't locked, you can DIY.
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