4 Wheel Drive/SUVs: 93 Ford Explorer Repair Question, air fuel mixture, auto parts stores

Question
I have a 1993 Ford Explorer, 4.0L V6.

I recently had the intake gasket replaced.

Shortly thereafter, approximately 2 weeks later I experienced some problems with the engine idiling extremely rough.  It would even rev up, by itself, almost to 2500 RPMS.  I noticed a HUGE different in fuel economy and the truck runs very poorly.

The Check Engine Lights comes on as soon as the truck is started.  When driven, a lack of power is evident.

When I slow down it the idle becomes very low, almost to the point where it wants to stall.  When backing the truck up it will generally stall out.

The idle will then rev up by itself and then calm down a little.  I also get alot of black smoke coming from the tailpipe and a strong odorous smell of fumes.

I replaced the PCV valve and checked all the hoses.  The only difference is the PCV valve I bought was $2.99 and didn't come with the wire harness like the OEM FORD PCV valve did.

I took off the IAC and cleaned it thoroughly.  I inspected the air filter, hose, MAS and all seems to be fine.

What might this be?  What can I do?

JEFF
cop0023@hotmail.com

Answer
Jeff,

The first question, is why did you have the intake gasket replaced?  Was the Explorer having similar symptoms as it is now?

It sounds like the air/fuel mixture is running extremely rich.  This could be caused by one of several of the emission, or fuel sensors.

I would suggest that you take it to a reputable shop, and have them run a diagnostic test to see if they can pin point the problem.

If you want to try to diagnose the problem yourself, you will need a repair manual for the Explorer.  You can purchase a manufacturer's shop manual for it from a dealer.   They are quite expensive, normally costing, around $100.

A Chilton's or a Hayne's manual would be a better buy, as they can be purchased at most auto parts stores for $20.  They have a lot of information on basic trouble shooting, and repairs.  These manuals are designed for a year or range of years for specific vehicles, and are invaluable if you are planning on doing any repairs, troubleshooting, or maintenance yourself.

Carl