Gentlemen, my grandad is getting code 159 on his '93 Ranger 4.0... I understand this is not the Ranger subforum, but code 159 is code 159.

A shop pulled the code and replaced the MAF senor, but it's still bucking and stalling in gear. The shop says that the MAF senor is reading correctly and sending the correct signal to the computer, but the computer isn't fuctioning right and needs to be replaced. Appearently, more than one MAF senor has been tried and similar Rangers in junkyards near him have already been stripped of their computers. The problem isn't as bad out of gear.

Now, we are 2 states away so that's what I was told over the phone... Haven't looked at it, drove it, or have anyother info at the moment.

I would appreciate anyone's input. At least a second opinion should be in order, unless this is a common issue...

Thanks guys.

 

Deleted Deleted, double post.

 

You did not say if this was a KOEO or EOER code but here is what both mean below.

Key On, Engine Off Self-Test DTC 159 indicates that the Mass Air Flow (MAF) sensor is out of Self-Test range and that the MAF Signal was greater than .70 volts during the Key On, Engine Off Self-Test.

Engine Running Self-Test DTC 159 indicates that the MAF Signal was not between .20 and 1.50 volts during the Key On Engine Running Self-Test.

NOTE:
DTC 159 could be generated by the garage exhaust ventilation system. Remove ventilation system and properly vent to outside atmosphere. Rerun KOEO Self-Test.

Possible causes:

-- Damaged Idle Air Control (IAC) solenoid.

-- Damaged MAF sensor.

-- MAF sensor partially connected.

-- Damaged Powertrain Control Module (PCM).

-- Air leak before or after MAF sensor.

 

^ Thank you sir, I will foward this to him.

Also, the motor seems to run fine with the MAF unhooked.