Questions and Answers

Explorer Gets Poor MPG Q. I'm having a problem with my 1994 Ford Explorer 4X4. The gas mileage has dropped off significantly and it seems to be running hotter than normal. The check engine light comes on while driving. I had the codes pulled and got a 136 (heated oxygen sensor indicates lean condition, left side) and a 411 (unable to control RPM during low RPM self-test).

I replaced the TPS and the spark plugs with the correct type (double-platinum) and still have the problem. The vehicle seems to be running O.K. except for the check engine light. I recently replaced the canister-purge valve due to a code 565, but that is not an engine running code. I also put in a K & N air filter trying to get at least 15 miles to the gallon. My father has the same vehicle except a year older with 150,000 miles on it and gets a lot better mileage than I do.

I have the 4.0 liter V-6 with auto transmission. It has 71,000 miles on it. The fuel system has never been flushed except for fuel additives. Any advice you could give me on this problem would be greatly appreciated. Thank you for your time.

John

A. Diagnostic Trouble Code (DTC) 411 indicates that during the Engine Running Self-Test, engine rpm could not be controlled within the Self-Test lower limit band. This indicates a problem with the Idle Air Control Valve (IAC) circuit. Depending on the type of valve installed on your engine, it can be cleaned out and reused. If the electrical connector end of the IAC comes straight out, it can be cleaned. If it comes out at a 90° angle, it can not be cleaned and must be replaced.

Also check the basics. Make sure the timing is set correctly, that there are no vacuum leaks and the throttle linkage and throttle plate are not binding.

Additional Information provided courtesy of ALLDATA