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Terry @ BMS Terry @ BMS is offline
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Join Date: Jan 2008
Default 01-25-2018, 08:50 PM

Originally Posted by dbsears
Hi Terry,

Couple questions and slight back story. I have a '16 340i 8AT with nothing but BMC drop-in filters and I've ran two separate Piggyback tunes. One was a popular branded JB+ equivalent which worked great but it's fixed additive boost values took away some of the linear B58 feel and also hindered shift speeds. I then switched to one of the very popular JB4 equivalents which had amazing power but significantly hindered shift speeds at redline and under power. I also received multiple drivetrain malfunctions during 1-2nd gear pulls which has almost left me stranded in an intersection. With that said I'm looking at a JB4 and hoping some features along with CANBUS has this mostly figured out. So my questions are:

- What Map would be appropriate for PNW 92 octane gas, I assume Map 2?
- Is this boost curved tailored for the RPM signal or is it a fixed 4psi across the whole rev range?
- Does the JB4 suffer from significantly slower shift speeds at redline and under power with the 8AT torque intervention? I've seen this mentioned on just about every piggyback.
- Have you seen any drivetrain malfunctions on the latest Firmware?
- I'm looking for an OEM like linear powerband, just a bit more oomph and drivability to what a JB+ offers.

Hi Terry, I was hoping you would be able to answer the above questions. Still looking at going the JB4 route but hoping you can shine some light on the shift speed concerns? I still see some people mention this one?
Sorry, missed your post. The short answer is with the JB4 you'll have a log more tuning and diagnostic flexibility. But I don't know if it will solve whatever issue you had with the other piggyback system. It depends why you were having an issue. Easy to install and evaluate though. Map2 is a good starting point.

In terms of fault codes if you get one there is something wrong that needs to be fixed. First step in fixing it is to read the code and then use that to determine what triggered it. If everything is working normally, there will be no fault codes.

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