PCM Diagnostics & Tuning - Bad gas mileage




View Full Version : Bad gas mileage


rob69zombie
08-14-2011, 07:22 PM
Hey guys. I recently sold my bolt-on SS and bought one that was cam'd and tuned by Speed Inc' back in 04. It has pacesetters, ory, Corsa (that I just installed) and a baby cam; that's it. Why would I be getting 15-17 mpg's? Highway and city driving vary, but only slightly. I'm hoping it's just in the tune so I plan on going to Mayhem Motorsports in a few days to have them do it all over. It does smell a little gassy, but I thought that could have been the absence of cats. I changed the plugs and cleaned the maf but it still can't get over 260/ tank. How hopeful can I be for the tune to help?


SMOKINV8
08-14-2011, 08:52 PM
It depends on the cam. The more overlap you've got, the worse fuel economy you're going to get. Plus if it's an auto, it's probably got a converter. That won't help things any either.

If you're sure you have no exhaust leaks (especially upstream from the O2's), you're probably not going to gain a lot from the tune.