Problem: a Ford truck with codes P0171 (bank 1 lean) and P0174 (bank 2 lean).
Snap test with a scope tool: 1 trace (Blue)=fuel line pressure; 2, TPS(Red); 3, MAP(Yellow); Point 4 means fuel line pressure is 40 PSI, and point indicates fuel line pressure in only 26PSI, Conclusion: a fuel delivery problem. |
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