Ford explorer maf wiring

[lilfordrunner]

I am all but finished with my 2.9 to 4.0 swap in the ranger. Took it out for the maiden voyage today. The idle is high (around 2k) and its running RIIIIIICH.
After doing some research here and on other forums I think it comes down to the MAF.

If the MAF Sensor and MAF return wires are hooked up backwards will that prevent the voltage from dropping when ignition is turned on? In the chiltons book, it says the voltage should drop (can't remember the exact readings) when the key is in the on position.

 

[adsm08]

No, because it is a resistance measurement, not a diode.

I would suspect the sensor first.

 

[lilfordrunner]

Do you agree with the other forums that a bad/dirty MAF COULD cause high idle AND running rich?

 

[PanamaExpat]

Yes because the PCM sees it as a cold start condition and is the same as running with the choke on and fast idle engaged on a carburated motor. There is also an air temp sensor in the plenum that feeds info to the PCM for adjustment.