I have a 94 F-150 w/5.8. I am getting a few trouble codes and I'm not quite sure what the proper process is to go about fixing them. Any help would be greatly appreciated.
I have been experiencing an intermittent hiccup in the idle and also a surging feeling in the power as i am driving. The check engine light comes on periodically for varying amounts of time and then goes off for varying amounts of time so I purchased a code reader and this is what I found. I have removed and cleaned the egr valve which was pretty clean to begin with, I have replaced the tps, idle air control valve, air charge temp sensor and egr position sensor. I replaced the egr position sensor because of the rough idle and it made no difference...i was just shooting in the dark before I got the code reader.
66 mass air flow sensor circuit below minimum voltage
31 egr positioner sensor below minimum voltage
32 egr positioner sensor below closed limit
38 idle track switch circuit open
53 throttle position circuit above maximum voltage

 

Im not 100% sure about this but I think I would start with that code 66. As I understand it, it uses voltage to send an analog signal to your PCM. If your MAF sensor isnt sending anything out then your truck really has no idea what so ever of how much air flow is coming through you system.

 

Well, I would start there but I don't believe this truck has a mass air flow sensor...atleast not in the normal place every other one I've seen has been. It would be nice to know exactly what that code means....

 

What kind of code reader are you using? I thought the codes should be three-digit by '94.

 

X2 It is uncommon for a truck of this vintage to use 2 digit codes. Not unheard of, but very rare.

 

According to my chilton EEC-V (OBD-II) codes are for 95-96 trucks. So he should be good with 2 digit codes.

 

OBD-I codes can be 2 or 3 digits. Ford started to transition from 2 to 3 digit codes around 1991. By 1994 it is very rare to have a truck displaying 2 digit codes.

Nobody said anything about OBD-II codes, you are barking up the wrong tree.

 

I have checked the codes manually in the past with a multimeter and came up with 2 digit codes then as well. I also came up with the 66 code then as well and I'm still a little puzzled about the mass air flow sensors location...

 

The 66 code in 1994 means you have a cold transmission (engine not warmed up).
That is not what the book says but it what it is most of the time.
The code is for the TFT sensor.
It has nothing to do with a mass air flow sensor.
Also you have a MAP sensor and not a mass air flow sensor.

By the way what transmission do you have?

 

It's an E4OD....but I just found one problem, the pcv valve had come out of the grommet at some point. Unfortunately when I tried to put it back in, the grommett pushed through the dang hole. And since Ford was gracious enough to make it impossible to get to it looks like I've got twice as much work now removing a bunch of stuff to get to it. Would an unhooked pcv valve cause any of these issues I'm having?

 

Well, I took the plenum off and put the pcv valve back in it place. Got a new plenum gasket and re installed it. Had the battery unhooked all day. Fired it up anf let it get to temp, checked the codes and got the exact.same ones. Now, my question is whether unhooking the battery is enough to erase the stored codes or is there another process. Hmmmm.....