Gilbert4455
Silver Member
I developed a fuel trim issue a while back and have been having issues nailing it down. At cold start my fuel trims are fine but once I’m driving at operating temps my fuel trims sit around 18 at idle. It sees to vary drive to drive beetweem +16 and 20. Fuel trims get better when I’m driving but still fluctuate more or less depending on revs and acceleration. Under heavier load fuel trims are close to 0. I’ve pressure tested the intake and tightened up all obvious issues. I cleaned my MAF and replaced the o ring and that helped dramatically but still produced the same behavior just better fuel trims. I pressure tested the intake and ended up replacing pcv and confirmed that there were no issues with pcv system or noticeable vacuum leaks with another pressure test. I also replaced my intake manifold gasket during that process. After about and hour drive the next day I noticed my fuel trims were slowly getting worse. I pressure tested again and heard no hissing from where I did around the pcv before replacement or anywhere else. I have also sprayed carb cleaner around intake manifold and any vacuum sources with no change in fuel trim or noticeable change in RPM. I’m not sure what to do next other than throw another intake mani gasket in. No Cels and car runs fine other than slightly noticeable movement in revs at idle.
