Fuel Injection ???

breakjunki · Post by **breakjunki** » Wed Jul 06, 2005 5:08 pm

I don't know if this in the right place but it's gotta go somewhere. I have a question for you mechanics out there from a guy who can almost change his own oil. My 91 ford explorer is running rich(efi) The intake/throttle body is sooted black, along with the spark plugs. At high rpm's 4+ it will blow the balck soot out the exhaust. But it seems to be running pretty well overall, so that kinda ruled out the injectors leaking. Someone suggested the mass air flow sensor and the o2 sensor any ideas guys.. Appreciate it.. Joe....

Chris from MI · Post by **Chris from MI** » Wed Jul 06, 2005 5:25 pm

Is the check engine light or service engine soon light on at all?

breakjunki · Post by **breakjunki** » Wed Jul 06, 2005 5:28 pm

Kind of, when it feels like it. its comes it goes. But the truck never runs different. It hesitates a little when you stomp on it. but its definitly running rich.

Jonathan · Post by **Jonathan** » Wed Jul 06, 2005 7:52 pm

Check the IAT (intake air temperature) sensor. I believe your Explorer used the same injection system as that era 5.0s, where the MAF sensor itself is a temperature sensor anyway, so you could call it the MAF sensor. I think Ford called it an air charge temp sensor or something along those lines, can't remember. Coolant temperature sensor is another possibility. Usually the IAT sensor is the likely culprit, but in the case that either one of those is faulty, the results are the same. Usually you'll have an open circuit on the sensor and the computer translates this as a very cold temperature (like -40F), since air is very dense and oxygen rich at that temperature, the computer adds fuel and runs rich to compensate. You may want to have it checked, a mechanic or qualified should know the approximate voltage that the sensor should produce at a certain temperature. You're really only checking if it has a voltage to begin with anyway, but it's good to know if it's accurate. If that's not the problem, the 02 sensor is always a likely cause. Of course, you'll want to clean your throttle body and replace your spark plugs after you get this fixed, maybe even take it down a country road and blow it out :)

Post by **GlassWolf** » Wed Jul 06, 2005 7:55 pm

take it to a garage.
hook it up to a diagnostic machine.
read the codes.

fix the reported issues.