Hello guys I am experiencing a problem with my multiwii board.
When I fly it in acro mode, after arming, all motors start at the same time and it is stable while hovering BUT when I put it in self level/ auto level mode and arm it, both right side motors start first and then after sometime the two left ones kick in. This causes my quad to drift rapidly and the problem doesnt solve even if I apply maximum trim.I had a bad crash in the morning because of this! Is this some kind of calibration problem? Can this be related to ACC calibration? Any help will be appreciated,
Thanks 

Lol tried to debug since months but i always had some peoblem with multiwii. tomorrow i am gonna make a new MW board with pro mini will post what happens. I didnt have any luck with MW till now . BTW have you checked the CG. It really matters.

It was because I had to adjust the ACC trim. Now I have another problem. Now, my quad drifts backwards. For correcting it, I put throttle stick to max and pitch stick backwards but no LED blinks are seen. When I do this with roll and forward pitch, it works and the LED blinks accordingly.when I have a mode 2 tx and multiwii version 2.4(latest). My throttle max value is 1950 as seen in multiwii GUI.
Any ideas?

If it is drifting backwards you have to throttle up to max and pitch stick should be moved forward.
Even doing so did not clear my problems. It always drifts.
BTW dont use FS-ct6b with multiwii .Even that causes some problems. Because sticks dont centre when released which may again cause a drift.
My multiwii sometimes yaw CW at very slow rate. It makes me frustrated .
I think the problem might be bad Centre of Gravity. Take care that CG is exactly centre so that all motors take same weight and easy for FC to maintain stability.

calibrate the acc and also trying triming the pitch a bit, check cg, and also check ur props are they good to fly? broken or cracked props may cause such drifts

CG is well balanced bro. When I try to trim acc , it takes inputs on roll (right and left) and pitch backwards but it doesn't take inputs when pitch stick is moved forwards (no LED blink).
P.S - I have a flysky th9x

Even i use the same radio.
Once check in GUI while increasing pitch. In order to trim the PWM value must go above 1850 . You might have accidentally set something wrong trim on pitch so it is going upto 1850. Post a screenshot which will makes situation more understandable .

I got it. Just adjusted end points and done!
I have a question about PIDs.
My current PID values are
Pitch --> P-1.6, I-0.021,D-23
Roll --> P-1.6,I-0.021,D-23
Yaw--> P-5.0,I-0.045,D-0.0
Now what is happening is that when I take it up and give it forward pitch input, it just over reacts quickly and bends forward like way more than what I want. Almost same on roll axis.
I didn't tune the yaw yet. I notice some slight wobbles while in the air but they are like 3-5 times once. It's not able to control height very well. When I push you the throttle to about 35% it hovers for a couple of seconds and then just wobbles and gains height rapidly.
These PIDs are a lot different from my previous quad PIDs in which P was around 6.8 for pitch and roll.
Can you please help me out in figuring this.
At base PIDs, it was 3.3 P for pitch and roll. With these PIDs it was wobbling a lot more. But I have a feeling that 1.6 is too low as most people have it around 4.
I am doing the tuning in acro mode

yes tune in acro mode follow youtube videos how to do it it takes time to tune the multiwii bt it flies well after also check for expo or rates on tx make them default it will avoid overshooting of roll and pitch

I went through most of the videos on YouTube but nobody has this problem of wobbling and uncontrollable gain and loss in altitude. Is my P too low?