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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > 6mt shift bog/lag with 2.02 std (Cobb)



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      05-05-2011, 10:45 PM   #1
Murf
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6mt shift bog/lag with 2.02 std (Cobb)

anyone else seeing this... dead spot-lag between shifts, am I shifting to fast too slow> is it a tune issue>

Feedback appreciated

Last edited by Murf; 05-06-2011 at 07:00 AM.
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      05-06-2011, 12:35 AM   #2
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What are you using Cobb?
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      05-06-2011, 01:47 AM   #3
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I'm going to take a stab at this b/c I've noticed this as well. I think that the ecu pulls back the timing when you jump back on the throttle after a shift in order to reduce the chance of any tip-in detonation from a temporary lean condition.

I don't have any data logs or anything to support this. It's just a guess.
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      05-06-2011, 02:53 AM   #4
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Even stock the car has shift bog if you shift very fast from 3th to 4th, I tried it before getting tuned. However, with GIAC Stage 2 I can induce bog extremely rarely, and I could never induce bog with Stage 2 Race.
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      05-06-2011, 06:59 AM   #5
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Yes sorry, Should have mentioned its a Cobb tune....
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      05-06-2011, 07:56 AM   #6
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Man I have felt the bog and it looks like it happens to all tune no matter what, it depends on your driving style. One thing im doing is shifting from 3-4 between 6k and 6,3k.
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      05-06-2011, 08:15 AM   #7
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Easy fix. I talked to.Cobb a out this the week the tune came out. I guess they didn't put it into the maps though. There's a flaw in stock programming that spikes timing as the rpms go down in Btwn a shift. Load is somewhere in the 40s and timing goes as high as 2x sometimes. They need to drop coming in that portion of the load table or implement a timing drop activated by the clutch switch.
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      05-06-2011, 08:35 AM   #8
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Yeah this is only happening on high rpm shifts, anything under 45-5k is pretty smooth. One other thing i've noticed is a slight stutter when flooring it in a higher gear then the car takes off. Do you think im spiking boost and actually feeling throttle closure before boost tapers? Would running a 91 octane map ameliorate this?

Thanks again for the feedback, I just came from a B7 RS4 and feel like im taking a crash course in turbo tuning lol...
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      05-06-2011, 09:01 AM   #9
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Quote:
Originally Posted by Murf View Post
Do you think im spiking boost and actually feeling throttle closure before boost tapers? Would running a 91 octane map ameliorate this?
Logs are your best bet to get a better idea what is happening
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      05-06-2011, 09:03 AM   #10
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Quote:
Originally Posted by Clap135 View Post
Easy fix. I talked to.Cobb a out this the week the tune came out. I guess they didn't put it into the maps though. There's a flaw in stock programming that spikes timing as the rpms go down in Btwn a shift. Load is somewhere in the 40s and timing goes as high as 2x sometimes. They need to drop coming in that portion of the load table or implement a timing drop activated by the clutch switch.
Help me out here, when timing goes up, what is the consequence?
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      05-06-2011, 09:07 AM   #11
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Help me out here, when timing goes up, what is the consequence?
There are two forms of this bog. One is boost overshooting which cause throttle.closure....not harmful. The other is caused by these timing spikes. When you feel that bog what you are feeling is the car knocking. Hopefully some one at Cobb has some shifting skills and can slam.a.car into.gear like some users on here can.
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      05-06-2011, 09:24 AM   #12
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I've had lots of bog/hesitation when flooring the car in low gear at high RPM with the Cobb. Car hesitates for a second, then takes off. Kind of like turbo lag...
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      05-06-2011, 09:34 AM   #13
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Did you ever log anything? Or did you just continue to floor the car?
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      05-06-2011, 10:13 AM   #14
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Quote:
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Did you ever log anything? Or did you just continue to floor the car?
Yes I did log...apparently I wasn't doing it right though. Someone told me you have to be in 3rd and then WOT. I have a couple of logs but the info didn't come out right. Oh well, the tune is gone anyways.
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      05-06-2011, 10:15 AM   #15
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How. Didn't it come out right. Can you post what you have? Email me the file if you need help with excel
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Yes I did log...apparently I wasn't doing it right though. Someone told me you have to be in 3rd and then WOT. I have a couple of logs but the info didn't come out right. Oh well, the tune is gone anyways.
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      05-06-2011, 10:16 AM   #16
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How. Didn't it come out right. Can you post what you have? Email me the file if you need help with excel
Can you PM me your email addy? I'll send what I have. I'm also no excel guru on top on it so I can't translate the raw data
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      05-06-2011, 10:23 AM   #17
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Sent....now that I'm looking at it again the RPM's don't change...must have done it wrong
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      05-06-2011, 10:24 AM   #18
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I'll take a.look at it once I get home. I'll post something up later tonight
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      05-06-2011, 01:10 PM   #19
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Quote:
Originally Posted by Clap135 View Post
Easy fix. I talked to.Cobb a out this the week the tune came out. I guess they didn't put it into the maps though. There's a flaw in stock programming that spikes timing as the rpms go down in Btwn a shift. Load is somewhere in the 40s and timing goes as high as 2x sometimes. They need to drop coming in that portion of the load table or implement a timing drop activated by the clutch switch.
this effects all tunes. Is it possible to implement a temporary reduction in timing separate from the timing table? I am thinking that you cannot, as this would be altering/adding to the program logic. A flash can only change the data that's implemented by the program.

Changing the timing table would mean reducing timing along a 1000rpm range in many load cells, since the speed and rpm of the shift would decide what load/rpm you hit.

Anyway very curious on this.
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      05-06-2011, 01:15 PM   #20
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Hence the clutch switch timing reduction which is already programmed into the car. Sit a idle and watch timing.....now press the.clutch in and see what happens
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      05-06-2011, 04:52 PM   #21
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Quote:
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Hence the clutch switch timing reduction which is already programmed into the car. Sit a idle and watch timing.....now press the.clutch in and see what happens
confirmed just need to increase the time period of the retard.
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      05-06-2011, 05:41 PM   #22
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Quote:
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confirmed just need to increase the time period of the retard.
my thoughts exactly
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