I installed a fuel pak on my 04 dyna and after start up the cel comes on briefly then goes away.
Bike runs like crap too. I am not a fan of piggy back systems but thought how bad could it be? I just had to replace the ecm and the dealer flashed it and it seems to run rich. Thought the fuel pak would help some but i think it's worse now and the cel comes on and goes away after start up. Is it worth trying to see if vance and Hines can tweak the settings or would i be doing more harm than good?

 

 

How does it run like crap? Specifically what does it do and when does it happen? How do the plugs look?
Since the cel came on you should check for codes, even though it went out. It can't hurt to contact V&H and make sure you have the right map in there. You can also pull the fuelpak and see if it runs any better. Make sure the contacts are clean and straight, using a little dielectric grease would be a good idea, too.

 

It runs rough like timing is off. I contacted vance and Hines and a rep sent another map. Entered that in and still ran like crap. Runs much better without the fuel pak. Im really surprised because you would think it would be pretty close to decent good running but it's horrible.

it's only a stage 1 with big radius exhaust. I replied to rep with update and concerns and have not heard back from him, so I'll take the pak off and stick to real tuner with dyno run.

 

Used to be that V&H would test the unit if you sent it to them, and if it's good you will get a letter saying that. Ask them about it.
If you haven't already you should check for any intake and exhausts leak. No amount of tuning can compensate for a leak.