My SES light has been going on and off ever since i installed my RR CAI, Magnaflow catback exhaust, and RR underpully. i ran the code with a buds code reader and it came up with # P0171 and said something about a leak. can anyone maybe trouble shoot this problem for me from the code?

 

That's a lean code. Double check your installation. You likely have a leak at the MAF or where the intake meets the throttle body.

 

I had the same problem, same code, same everything. I never got it figured out. I had checked all the connections over and over. Cheap intake of not, you'll run into issues either way but mine involved idling issues every time I started it, almost like a loss of power and the rpms would surge around even when I was giving it alot of gas. I got terrible gas mielage because once the CEL came on, it wouldn't go off unelss I reset the ecu and once I did that, it would run rough for 10 minutes. Some intakes just don't work well with Mitsu's, dont know why. a buddy of mine could never get his running right on his galant, so the other ppl out there that have no problems, cheers to you for getting the right brand

 

Have you checked your APPS!?!?! (Accelerator Pedal Position Sensor)...
I had the same problem and my APPS was broken... bought a new one and doing great!

 

OOoOO i have a fun story on "Service Engine Soon". Today mine came on and i was reading the manual and basically just like WTF. turns out the like 1 possible outcome..my gas cap wasnt screwed on tight enough was actually the issue. WOOT im a tard!

 

Try some maf cleaner. CNC makes some. I did that when I had mine and it worked fine. Also make sure your filter is on all the way and not sucking on anything. The maf can be horrible to get into the RRM CAI, make sure it's 100% flush before you screw it down. If it isn't your o-ring isn't seated properly and will run lean.