[iEatSand]

Have been having some weird/hard shifts from 3rd to 4th gear. Auto 2008 135i. Everygear is buttery smooth besides that one. When I shift from 3rd to 4th and low rpms/not giving it gas it shifts fine. When I floor it and go WOT shifting 3rd to 4th it's fine. It has trouble shifting around 3-5k RPMS if I'm not flooring it, or coasting. I'll shift to fourth, it will try and engage, then kick me down into third(but still say it's in 4th). If I don't downshift back into third when it happens it throws a transmission malfunction.

I've been reading around about this issue and that it has happened with other models like 545i's, but haven't found a thread about it happening on a 135i/335i. The trans isn't slipping at all. I could do a fluid change but I'm curious if there's a vacuum line going to the trans or a solenoid that has to be replaced? I know it's a mechatronic ZF trans like my old e55 amg. Am I able to rebuild it with the mechatronic solenoids??

I don't want to throw money at trying to fix the problem when it could end up just needing a new transmission. I've been playing around with the idea of getting a 6mt parts car for a swap.