DCT bogged down and switched to Neutral

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RSL

Sergeant
Aug 11, 2017
395
I tried it more than once over the years until I finally tossed it after the last time. The boost control is good and easy, but trade-offs come with it, not to mention potential gremlins. I'll spare you my experiences with it, but not a fan and will always recommend against them on DCT cars, even with a well-adjusted BEF. One day you'll take it out and realize just how much better it drives and shifts everywhere, no matter what you've done in the BEF while it was in. I used 4/4 once (didn't swap the pin) just as a test. I'd personally never leave that thing in there just for a "pass-through" controller.

I don't use meth, but understand its appeal. You shouldn't run a level that is potentially catastrophic without it, in which case, I'd just assume not even add it to the mix because it's easy to get carried away tuning with it and people frequently do.

Those boost profile/WG menus are a pain. I don't think it's just DCT, but I had issues at times too. If the menus are set low already, you're probably going to have to change output request in the flash. The brake to quick accel may need the same in the other direction to help it out, but would need to log to see what's happening and where for each of those issues...I'll try to avoid pointing out how slow and limited the JB4 logger is too lol
 

General.Massacre

Specialist
May 14, 2018
59
Thank you for the feedback.
I've never tried flash only. However I've always been tempted on the 4/4 option as I have meth like I said. And have the FSB all wired up.
Could go the controller route and wore that in I guess. Would have to research and have a look what's involved.
Did you make more power with flash only. Apart from the additional smoothness?
 

aus335iguy

Captain
Nov 18, 2017
1,036
All ”piggy back” computers have limitations. They are essentially tricking the DME into delivering a different state of tune. Its effective but will never be as refined as a good DME flash. People have varying experiences with it. On DCT cars it’s more common to hear stories like yours. Not because it can’t be made to work well, just because even with RSLs level of experience it’s difficult to get closer to perfect. Personally I’m good with mechanical issues and old school port EFI but I don’t know how to tune these things and so I run a custom tune from BQ who is known for his experience with DCT. Never looked back after he tuned my car.
 
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RSL

Sergeant
Aug 11, 2017
395
Thank you for the feedback.
I've never tried flash only. However I've always been tempted on the 4/4 option as I have meth like I said. And have the FSB all wired up.
Could go the controller route and wore that in I guess. Would have to research and have a look what's involved.
Did you make more power with flash only. Apart from the additional smoothness?
Pretty much the same. Only dynoed one, but run multiple logs/VD daily for years at the same location for plenty of comparison. JB4 is primarily just a boost controller. Flash can obviously run the same boost, just takes more work than typing numbers in boxes. As far as power goes, mods/boost/octane being equal, that will be determined by the actual tune, which is the flash.

You don't have to get rid of it or make a decision based solely on my input/experience. You can easily take it out, try flash only without meth for a bit and decide for yourself whether to put JB4 back in. If you're happy with it as is, don't change a thing. It might be fine 4/4, but it obviously still has its hands on bus/signals and I frankly will never trust that everything that goes in is what actually comes out. I also have suspicions that operating frequencies or how data is intercepted has an effect on things. I swear my car shifts differently just depending which logger I am using.

All ”piggy back” computers have limitations. They are essentially tricking the DME into delivering a different state of tune. Its effective but will never be as refined as a good DME flash. People have varying experiences with it. On DCT cars it’s more common to hear stories like yours. Not because it can’t be made to work well, just because even with RSLs level of experience it’s difficult to get closer to perfect. Personally I’m good with mechanical issues and old school port EFI but I don’t know how to tune these things and so I run a custom tune from BQ who is known for his experience with DCT. Never looked back after he tuned my car.
That's really the key, especially for DCT. Underreported loads/torque from JB4 can be worked around up to a point for WOT, but PT is extremely difficult to compensate for with current tables. Torque output wasn't even a param routinely available on the JB4 logger for a long time.

As much time was spent and as good as it would get, I convinced myself it was almost as good after a month or two. Then it started doing goofy stuff with the LPFP, ended up pulling it out after trying several things and man I had myself fooled on the shifts lol It was like DriveLogic got installed just going back to flash only (and LPFP problems disappeared).

Something to be said for just buying a tune, flashing it and enjoying the car. No such thing as a finished tune on my car, always messing with something.
 
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