HORRIBLE GAS MILEAGE POST RECALL (ಥ﹏ಥ) ¯\(°_o)/¯

[theadmiral976]

Originally Posted by mswbrz

Would this cause any feel in any less performance , or any cells to pop ?


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I wouldn't make decisions about what to check based on whether or not a CEL has or hasn't appeared. Code setting criteria are not always straightforward and are easily changed with mapping (meaning something could have happened during Ecutek tuning).

Small vacuum and exhaust leaks can cause mileage to drop significantly without tripping a code. If you can, as others have suggested, I would go over your engine with a very careful eye for any vacuum system issues (missing, loose, cracked, improperly installed hoses), including pulling the PCV and checking that the check valve can freely move under light spring pressure. I would also make sure all gaskets are installed on all air intake and exhaust areas. Check the throttle body for proper installation (it has a thick o-ring style gasket that can easily be rolled when installed).

If possible, log parameters including RPM, manifold vacuum / boost, MAF voltage, MAP, short and long term fuel trims, throttle position, engine load, and coolant and oil temps. This can help pinpoint when in the drive cycle an issue may be occurring.

If all of that is inconclusive, the most efficient way to look for leaks is by using a smoke machine.