ok so after practicing for weeks I have it cracked ( at least on player one side lol). I found that watching your opponent as they fall gives me good timing for my dash input. I dash just before they start coming down. After my dash I go df, db, ub, uf (just like an spd). Time to try player two side now! 
You can always start your dash when Dee Jay stops flashing yellow.
i think this is the hardes bnb combo in the game guile flash fadc u2 is much easier for me
i use shortcut after dash downback,up foward ultra comes out almost every time but my problem is i cant dash early enough
out of 10 trys 1 connect any tipps at this point i stick with u1
Could you post a video of you attempting it? From both sides as well. Iād like to see when youāre putting in your dash.
I cannot for the life of me dash from downback on player 2ās side 
Iām pretty sure Iām the only one that does walk-u2 anymore. I get āWTFā messages all the time. As a pad player this has become very reliable and I use it all the time since it works on about 80% of the cast. I canāt dash u2 for the life of me so I just stick with walking and using u1 on the rest of the cast that it doesnāt work on.
I pretty much got it down on the right side. I am starting to get the feel for the dash U2 on the left just need to make it more consistent. Pizza who can you land walk U2 on for reference. I have a easier time doing walk U2 on the left so iāll use it till i get the dash down.
Off the top of my head, walk U2 doesnāt work on the following characters: Juri, Cody, Guile, Dudley. There might be a couple more, but those are the ones I know for sure. Walk U2 really does work on most of the cast. Unfortunately, I find myself going for EX MGU on wakeup a lot because of it. Bad habit, but I catch so many people with it.
Edit: Forgot to add Fei Long and Adon
So the list of characters that walk->U2 does NOT work on:
- Juri
-Cody
-Guile
-Dudley
-Fei Long
-Adon
-Hakan
-El Fuerte
-DeeJay (how ironic)
**It works on the rest of the cast. **
So break it down. Just do the EX MGU then do just down back and dash. Itāll feel weird, but if you can do it from 1 side, it means you can do it from another. Your hands just have to get used to it.
Hardest bnb for me is Yangs.
2nd Reka, FADC, U1. Impossible for me to do!!!
I have never encountered a single Yang online doing this!!!
THe only time my opponent was doing this was offline, I was totally lost for words. Well and he played on pad! Might be easier and faster compared to a stick I dont know.
Yeah man, that Yang one gives me some troubles. I got it after trying a bit, but itās a tight window. In terms of DeeJay though, I didnāt know that if you were going for Raw Ex Mchgn Upper into Ultra 2 you shouldnāt mash buttons. Iāll go practice it again, I keep missing the timing for Ultra 2 to connect, maybe thisāll make it easier.
landed my first dash U2 combo in a match on PS3 last night and it was magical.
Congrats man! Whatās your preferred motion when youāre on the 1P side?
I noticed pikotan525 does dash, db, then half circle up forward. Iām having greater success doing it this way instead of dash, half circle up-back.
Oh and props to anyone who was landing this back in Super, damn near impossible.
Thanks. For me personally I have the most success doing the dash then the half circle up back. Also I have a easier time doing it on the P2 side than P1.
Iām having trouble landing this even in 2012, and when I look at other stuff Iāve landed it feels like I shouldnāt have any problems getting it done.
So far Iāve identified two problems, one for each side of the screen, and I was wondering if there was any tips you could give me to grind it better.
1P problem : The timing feels right but I, for some reason, canāt get down back when doing the J motion. I read my inputs and they go forward, down-forward, down, back, up-back.
2P problem : I almost always get dash ultra too late. My dash game is ass apparently.
With the inputs I find it easier to go from the dash from F, DB, UB or number notation if you are on P1 side 6,1,7. The timing is a not that hard just watch a video and break it down piece by piece.
You mean deliberately skipping the DF (or rather accidentally on purpose hitting it and skipping the), D in this case? Iāll have to try that when Iām not at work, thanks.
I found that if i go straight DB the game registeres a DF and D motnion anyway. It could be the way i slide the stick but generally I found that the imput registration for SF4 is pretty slopy/loose. At the end of the day experiment. The way I learnt the timing for the dash is by download a youtube video of a player doing it in game and then stepping though frame by frame with VLC to see what the frames looked like before the dash and what hight the oponent was. Hope that helps, itās not that had once you get the feel for it.
Pretty sure the DF is not required anyway. Any forward motion is fine.
On a different note, dash u2 and walk u2 is much easier on a hitbox. I just got one and i can barely move/jump properly with any character, yet dash u2 is easy.
It isnāt; you can actually input your dash, go down back then go up forward and it will work.