Marcos Beltran
OBS Enthusiast
I have a 96 gmc sierra with 4.3 V6. At first truck idled normally but bogged down when accelerating, sometimes would shut off. Borrowed a maf sensor from a buddy and is driveable now and made a big difference but if i get on it from a stop it's sluggish at first. If i gradually get into it, it drives good. Now im getting some long term fuel trims that are off big time. On LONGFT1 and LONGFT2 im getting between 16 and 25 which points to a vacuum leak. I made a homemade smoke machine and im not getting any leaks. Ive searched up and down using a flashlight and all. Jacked up the truck and nothing underneath either. I do get smoke coming out of the box where the air filter is but im sure that wont cause the vacuum leak. What else could cause the LONGFT's to be off like that? Fuel pump is new and has the right pressure. Any ideas anyone?