[lookalikehuuh]

So something strange I noticed earlier this month since I had to revert my tune to stock for California smog.

Car has been tuned for a few years now on E50 tunes, for as long as I can remember the car has had that 6HP hard down shift into 1st gear when coming to a stop. Well California now checks for modified software on the DME so I removed MHD entirely for smog and the transmission was freaking smooth as butter.

In the ~250ish miles that I drove the car on the factory software there was never a single instance of the hard down shift. Yesterday I re-installed the tune because well.... the stock power levels just aren't as fun and the hard downshift came right back immediately.

For science, I removed MHD again and... yep you guessed it smooth as butter, flashed Tune again and BAM, hard downshift is back once again. It appears to be super repeatable on my particular transmission,

I probably should just do the sleeves and a trans fluid change but can't help but wonder what MHD modifies in the transmission that is causing that hard down shift to occur in a repeatable manner. I also haven't had time to look and see if somehow the transmission adaptation values have changed but likely will be my next step.

Anyone else experience this or has seen a thread about this issue?

[Saif2018]

Originally Posted by lookalikehuuh

So something strange I noticed earlier this month since I had to revert my tune to stock for California smog.

Car has been tuned for a few years now on E50 tunes, for as long as I can remember the car has had that 6HP hard down shift into 1st gear when coming to a stop. Well California now checks for modified software on the DME so I removed MHD entirely for smog and the transmission was freaking smooth as butter.

In the ~250ish miles that I drove the car on the factory software there was never a single instance of the hard down shift. Yesterday I re-installed the tune because well.... the stock power levels just aren't as fun and the hard downshift came right back immediately.

For science, I removed MHD again and... yep you guessed it smooth as butter, flashed Tune again and BAM, hard downshift is back once again. It appears to be super repeatable on my particular transmission,

I probably should just do the sleeves and a trans fluid change but can't help but wonder what MHD modifies in the transmission that is causing that hard down shift to occur in a repeatable manner. I also haven't had time to look and see if somehow the transmission adaptation values have changed but likely will be my next step.

Anyone else experience this or has seen a thread about this issue?

Do you have XHP transmission flash option selected under MHD when flashing?

Would recommend you get XHP if you haven't already,

Your hard downshift into 1st can be resolved easily by modifying some custom (shift map/throttle blip) settings in XHP.

You want to do, Seals, Sleeves, Solenoids and Fluid for a full transmission service.

[KrazyKiwi]

Maybe try resetting the transmission adaptions, this made shifting better for me on MHD.

[iqraceworks]

Originally Posted by KrazyKiwi

Maybe try resetting the transmission adaptions, this made shifting better for me on MHD.

....I would advise against resetting the adaptations. xHP also says don't reset them. ZF also says don't reset them. The only time you should reset them is if you do a full rebuild.

Like others said above.....shift solenoids and seals are probably what's causing the hard 1st downshifts. Mine did the same thing, new solenoids fixed it.

These transmissions do all kinds of weird stuff when you start messing with the software (MHD and xHP) and they have old filter and fluid, leaky seals, and old and sticky shift solenoids.

Servicing the transmission should be one of the first things anyone does before they even think about modding the car 👍