Unitronic 1/1+ low RPM stumble in 1.8T

[mfennell]

Jumping in from the 1.8t forum (I have a '19 Sportwagen 4MO 6MT) to ask if any of the GTI owners have had problems with a stumble while moving easily from a stop in 1st gear. If I pull away gently with about 1/4 pedal down, I get one or two (or three if I'm especially lucky) bucks that hit around 1300rpm. I've attached a log of RPM, throttle angle, accelerator, and air mass. I didn't hold the pedal perfectly still (it's hard with the car bouncing around) but the RPM swings wildly exceed the movement. I've captured other logs with a steadier pedal and the same effect - I just like this one because it has throttle angle.

I've been 'working' with Unitronic, in the sense that I send them information but I'm not getting a warm fuzzy that it's going to go anywhere. Several people on the 1.8t forum had the same problem and got refunds (I wish I had encountered that thread before spending $800...). I'd prefer to just get it fixed because I like the convenience of managing my own tune, though logging and formatting data is hardly convenient. OBDeleven is a tremendous bargain but logging with it is a huge PITA and the time resolution sucks.

 

[MonkeyMD]

May not relate at all since I have a 5spd 1.8 and completely different tune (APR).

Anyway, I had the same thing initially and on part throttle would get a horrible bucking holding the pedal steady. To an observer, it would look like you don't know how to drive manual.

Anyway, after a little back and forth, APR came out with a second version that fixed this I issue.

Unfortunately, I don't know what the issue was.

Hopefully someone with more pertinent info can chime in

 

[Faceman]

I experienced something similar after upgrading my mounts. Using an OBDeleven to raise the idle speed by 50rpms helped smooth things out a bit.

 

[mfennell]

I got past the basic tech support and the tech director sent me a VCDS pre-selection file for some proper logging. VCDS cable will be in hand tomorrow.