(Solved) Help with Odd RPM Bump on Decel

V3 BETA TESTS
1

I am dealing with a weird issue I’m noticing on Decel and I don’t know if its something I can change or smooth out in the ECU Master V3 software or if I need to look at having the DSG tune recalibrated.

Specs.
2006 Audi A3 8P VR6 Turbo with DQ250 DSG with Unitronic Stage 3 software.
DSG adaptation performed recently after the V3 firmware upgrade to 3.24.

What I am noticing, specifically in 6th gear (Auto or Manual mode) is when letting off the throttle on an extended decel, such as coasting down a hill, the Engine revs slowly down as expected but then bumps back up fairly significantly. My initial thoughts were DSG or DSG calibration but I am not sure.

I have changed Decel (overrun) settings and played around with shift tables (blip etc) but nothing seems to make a marked improvement. It almost feels like there is a request to downshift to 5th gear. The action feel like it happens with the Car jerking and there is a slightly audible clunk. No gear is downshifted…the car just continues to decel from its new RPM back down out of overrun.

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I have poured over all the log data for the last 3 days to see if something stood out in regards to V3 software (This did not happen on V2, however the DSG is way different on V3 vs V2…much smoother, better shifts and less general DSG garbage). I just can’t determine the root cause… Is it the ECU doing something over CANbus to the DSG… or is the DSG just looking to downshift and the TQ table doesn’t support it? All theories at this point.

In anycase…Files attached if anyone wants to take a look and give me some thoughts. Other than this one nuisance…the DSG DQ250 is WAY better on the V3 than the V2 for my application.

Edit: The screenshot is from the attached log. Happens at about 8:04 in the log…and others as well. But the 8:04 instance is a perfect example.

Weird_RPM_Bump.emublog3 (5.6 MB)
V3_Beta_Config_3_Boost_off.emub3 (59.9 KB)

2

No longer an issue. Solved with TQ table modifications.

Can be closed.

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3

Do you use torque loses table or you left it 0 ?

4

I left it at zero… I was focusing on the wrong thing… My TQ values down in low KPA/Low RPM were higher than the values above it. So the Transmission was simply reacting to the values inconsistency that I overlooked.

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Rookie mistake likely, but the fix was smoothing out the transition from low RPM up the 20kpa column and the Transmission was much happier. It just got lost in the sea of new settings I guess, took me a while to find the root cause.

5

You can try to set losses to smal value like 5 or 10 and see what happens.

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