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aussie644 aussie644 is offline
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Car: W205 C43 2017
Default RPM Spike 3rd-4th (C43) - 01-08-2020, 01:02 PM

Hey,

Been running map2, logs have been improving (trims more stable, ignition looks better) as my car adjusts to the map/E30 blend. My issue is immediately following shift into 4th the RPM revs up like normal, then cuts back about 3-500 rpm before continuing to rev. The most noticeable aspect for me is the sound (quiet from the shift, loud, quiet again, loud, all in the space of a half-second). No traction issues.

Is this normal? I've attached a log below, its the last shift right before I release the pedal.
Attached Files
File Type: csv 11_37_21_Map-2-Trunc.csv (9.3 KB, 3 views)

Last edited by aussie644; 01-08-2020 at 01:03 PM.. Reason: Typo
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Default 01-08-2020, 01:38 PM

Log looks good and healthy, I don't see any indication of trans slippage in the log. Looks normal from when you shift, RPM is steady.


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aussie644 aussie644 is offline
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Default More examples - 01-08-2020, 06:05 PM

I'm very new to these logs, but it's definitely happening and I believe it can be seen in the logs.

I've uploaded two video where you can see/hear the rpm flutter, along with 3 more logs with 4 examples. The videos are from log 1 and log 2. I'll also include the time stamps of the spike in RPM.

I'm wondering/hoping this is something that can be fixed via the JB4 and not a tranny issue.

Time stamps
Log 1: 368.5
Log 1: 521.5 through 529.25 (very long change)
Link: https://youtu.be/TCqnSKjKS7A

Log 2: 173.97
Link:
https://youtu.be/7IztnAQJqBw

Log 3: 118.84
Attached Files
File Type: csv Map-2-tslip-trunc.csv (6.2 KB, 1 views)
File Type: csv Map-2-tslip2-trunc.csv (3.6 KB, 2 views)
File Type: csv Map-2-tslip3-trunc.csv (2.5 KB, 2 views)
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Default 01-08-2020, 07:12 PM

Don't crop the logs it makes it hard to view them. Instead just let us know the time stamp you want us to look at in the log.

If you think it's trans spin then the best options are to a) reduce boost in that area using map6 or b) add a BCM so we can "pull" boost higher improving the trans shifting capacity.


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It is the sole responsibility of the purchaser and installer of any BMS part to employ the correct installation techniques required to ensure the proper operation of BMS parts, and BMS disclaims any and all liability for any part failure due to improper installation or use. It is the sole responsibility of the customer to verify that the use of their vehicle and items purchased comply with federal, state and local regulations. BMS claims no legal federal, state or local certification concerning pollution controlled motor vehicles or mandated emissions requirements. BMS products labeled for use only in competition racing vehicles may only be used on competition racing vehicles operated exclusively on a closed course in conjunction with a sanctioned racing event, in accordance with all federal and state laws, and may never be operated on public roads/highways. Please click here for more information on legal requirements related to use of BMS parts.
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aussie644 aussie644 is offline
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Default 01-09-2020, 10:21 AM

Sorry about the crop, logs were too big to post.

I'll probably grab the BCM, so far the JB4 is some of the better money I've spent on the car so even if the BCM is only marginally beneficial, I'm not fussed.

It's heading to the dealer today for an unrelated issue and I'm wondering if it's worth showing him the video (and possibly having to answer some questions). Part of me wonders if it could be slip, its only in 3-4 and only immediately after gear change WOT, can't reproduce it anywhere else in any other gear or RPM range.

Few quick questions:
1) Does the log otherwise look healthy enough to bump up boost in other RPM ranges? (I'll be connecting green wire when reinstalling after dealer, but trims and timing currently look good I think)

2) Would the JB4 detect TCU codes? (AFIK the C43 torque limiter in the tranny would prevent over-torquing and would throw a code, something only a full tune could bypass I believe)

3) The default Map6 values are Map2 correct? Also, the boost at redline is what needs to be reduced and not the 4.5K rpm at the beginning of the next gear correct?

4) There's no boost by gear?

Thanks, I know you guys are super busy so I appreciate any input.
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aussie644 aussie644 is offline
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Default 01-13-2020, 11:05 AM

For anyone else experiencing an issue like this, I brought the car in for another issue and asked them to look at this specific one. They updated ECU TCU and I think one other system and it solved the problem
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Default 01-13-2020, 11:12 AM

Interesting


Burger Motorsports
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It is the sole responsibility of the purchaser and installer of any BMS part to employ the correct installation techniques required to ensure the proper operation of BMS parts, and BMS disclaims any and all liability for any part failure due to improper installation or use. It is the sole responsibility of the customer to verify that the use of their vehicle and items purchased comply with federal, state and local regulations. BMS claims no legal federal, state or local certification concerning pollution controlled motor vehicles or mandated emissions requirements. BMS products labeled for use only in competition racing vehicles may only be used on competition racing vehicles operated exclusively on a closed course in conjunction with a sanctioned racing event, in accordance with all federal and state laws, and may never be operated on public roads/highways. Please click here for more information on legal requirements related to use of BMS parts.
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