Re: poor gas mileage
Anytime you notice an increase in gas consumption, the O2 sensor is usually the culprit if the engine is in good tune and the fuel pressure regulator is working ok. An O2 malfunction will cause the engine to run rich, but won't richen the mixture enough to cause a noticable loss of performance in most cases.
The O2 sensor only sends data to the ECU when the engine reaches normal operating temps. Until then, the sensor runs in open-loop. If the sensor goes bad, the engine runs in open-loop all the time and generates a check engine light. However, an old sensor can cause a loss of economy and not generate a trouble code.
1992 Ford Bronco
E4OD- B&M Stage 2 shift kit
Full 3" stainless Bassani Exhaust
32" BFG's/stock suspension
"No replacement for displacement."
"Our lugnuts require more torque than most Honda's produce!"