1999 Ford Explorer Running Lean

FORD EXPLORER
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CRAZY_LIT
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  • 1 POST
i recently purchased a 1999 ford explorer sport 4 wheel drive automatic with a 4.0 V6 with 99755 miles on it.the check engine light came on & sometimes when u start it it will idle up to 3 grand then go down to 0 & act like its gonna stall so i took it to autozone where they put the code checker on it & they told me that it was running 2 lean could u please explain what that means & how i go about fixing it
May 19, 2007 at 1:44 PM
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RUDPRO
  • ✓Experienced Mechanic
  • 224 POSTS
It means the air fuel mixture has too much air mixed with the fuel. It could be caused by a lot of things, a bad mass airflow sensor, vacuum leak, low fuel pressure from a dirty filter. I'd check for vacuum leaks and check the fuel pressure. If that's not it you might need a code scanner that shows live data while the engines running and see if everything is within specs on the sensors.
May 20, 2007 at 6:38 PM

Suggested Repair

A lean condition means too much air relative to fuel. Check for vacuum leaks and test fuel pressure, including a possibly dirty fuel filter. If those are normal, scan live sensor data and inspect the mass airflow sensor.

Conversation Summary

The owner of a 1999 Ford Explorer Sport with a 4.0 V6 reported a check-engine light and occasional high idle followed by a near stall. AutoZone said the engine was running too lean. The expert explained that the air-fuel mixture contains too much air and recommended checking vacuum leaks and fuel pressure, then using live sensor data if needed; a bad mass airflow sensor or dirty fuel filter are possible causes.

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