code po171,new o2 sensors both different map sensor .secondary fuel trim to high

Question

nothing has changed problem,secondary fuel trim to high

Answer 1

P0171 System too lean

Vacuum leaks are usually the main cause for the lean code condition. You may have to go as far as using carburetor cleaner and spray at the intake manifold if you have a data stream note any changes on the fuel trim. Another and this is the worse case scenario , is to notice  the upper radiator hose if it is over pressurized or you are loosing coolant. in some causes it a headgasket. you already ruled the 02 sensor, now you rule the mechanical. the best test is a leak down test, not a compression test.

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