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as said in the title

 
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it all depends ont he fuel system that your using. but usually yes it does until you get it tuned correctly. i hope you havent turbo'd you car with out a fuel system!!

 
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what do you mean when you say "fuel system"?

 
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some sort of engine management system that will account for the extra fuel that is needed

 
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If done "correct" no

if you want to turbo your car

without proper resurch... yes you will have a "cel"

 
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even with tuneing it will still come on from time to time.
mine has been tuned twice and it still comes on every once in a while but i have had it checked on and everything is ok. just depends on y it comes on!!
useually comes on for misfires though.

 
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If you have to ask the question, then yes, its going to be on... probably all the time. Time to do some homework before you **** it up royally.

 
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well i hooked up a 12:1 fmu if that makes a difference. and i'm only running a 14b turbo with 4 psi and a sidemount.

 
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well unless you converted to a return system or at least a makeshift return system then the FMU isnt doing you any good. you probably also need a missing link to run with the FMU to trick the map sensor and bleed off boost so the ecu doesnt freak out. but an FMU is the biggest band aid in the whole FI market. youll get flat spots and leans spots in your air fuel ratio causing lost power and possibly make the injectors clip if your running too much pressure. you need to do some serious homework man. it sounds like you really dont have a clue what your talking baout or what problem you are really facing. go buy " Maximum Boost" by corky bell. it should help explain a few things and hopefully get you pointed in the right dirtection and away for the current set up you have.