Expert: Sean Halliday - 3/23/2010

Question
my car starts but will die if i don't keep giving it gas and when it runs it makes a popping noise but not as loud as a back fire,its a 99 Mitsubishi gallant gtz 2.4L

Answer
Sounds like a large vacuum leak or leak at the intake manifold.This popping sound may also be the maf sensor going bad.Has the check engine light come on?Test the vacuum with a vacuum tester which you can get cheap at any parts store.It will tell you whats going on as it will include detailed instructions.The 2 things i mentioned are the most common causes for poor running and bad idle,the popping sound is too much gas in the cylinders and misfiring at the wrong time.False air getting in will cause this hence the maf sensor may be bad, im pretty sure its a major air leak into the intake.Look also at the large boot from the air filter to the maf sensor.