Engine Hesitating

[Siq67Lark]

I apologize if this has been covered before, but I have searched for almost a week now and cannot find information that can help. I have a 2005 Expedition EB and until recently has ran great. It has 82k miles and about a month ago I threw on a K&N CAI and a bully dog triple GT tuner. After installing these two things and adjusting the settings on the tuner to match my Expy such as engine displacement and tire size, I took it out for a test drive and the engine sputtered like crazy from 2500-5000 and another issue was that the tranny did not want to up shift when I was getting on the freeway (held at 4000) and I had to let off significantly for it to finally shift and it was a harsh shift. I then uninstalled the tuner and restored the ECU to factory settings, but I still get sputtering (now only at higher rpm under load) and the tranny still wants to hold in first on an on ramp. It also threw a code for #2 cylinder (P0302) so I checked the ohms on the injectors, got a coil tester and it sparked no problem, and I even checked the plugs and they tested ok too. A couple days ago I replaced all the spark plugs since they were the originals and I figured they could be a problem, but if not oh well it was time to replace them anyways. Once on the freeway and cruising it drives perfect and around town it does fine too, but I have been babying it since this issue happened. I also know it needs a new belt, but I have been on a very tight budget as of late and have to wait to get it. I was wondering if anyone else here has had a similar problem and if so how did you fix it? Also could the coils or injectors work fine at low rpm and then under load they faulter? If so how can I test that? I know this is pretty long, but I didn't want to leave anything out. If you need any more info I'd be happy to give it.

 

[stamp11127]

Further reading:

http://www.obd-codes.com/p0300

Only difference in codes is yours specifies the cylinder. Considering what you originally changed, filter and programer, which one on the list was affected most?

Double check your ecu settings and connections. Misfires can also be caused by vacuum leaks. Don't ask me why but I've personally experienced it.

 

[Siq67Lark]

Thanks for the link. I am starting to think the bully dog didn't really return my ecu to factory settings because when I called customer service they said my vehicle isn't a recommended application (worst customer service I have ever dealt with though). I was using the F-150 setting, which I assumed would be the same but apparently not. Nothing is loose or not connected and the injectors are firing correctly. I did a leak down test and didn't hear anything out of the norm so I think I will just have to have my computer flashed.