Hi, help needed with my 1993 351w 5.8 efi.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
<o></o>
She starts first time and runs for about 10 seconds but then cuts out. She is then really difficult to start and when is running runs lumpy and changes gear harshly.<o></o>
<o></o>
I pulled the codes<o></o>
122, Throttle position sensor below minimum voltage.<o></o>
334, EGR valve position sensor voltage above closed limit.<o></o>
631, Transmission control indicator lamp (TCIL) circuit failure KOEO.<o></o>
<o></o>
I don't really understand what these mean.<o></o>
Any explanation or info to get me back on the road would be very much appreciated.<o></o>
<o></o>
Best regards<o></o>
Allan<o></o>

 

Ford Fuel Injection Throttle Position Sensor (TPS) Here is how to check the TPS. As for 334 I would remove the EGR valve and clean it. For 631 check the wires for cracking in the shift lever.
Not an expert so just my thoughts.
Good luck.

 

Thank Lazy K, I have replaced the throttle control position sensor, still same code. when probing for voltage reading there is no signal, do you know where there voltage is sent from?
I ran out of time so never got to the egr but will be able to work on her again on monday so if anyone can give me something to think on until then I would be very grateful.
Best regards
Allan

 

If you unplug the TPS wiring connector you should have the 5.0V ref voltage at one of the pins (as shoun in the link). This should come from the computer.
If you look through the link I gave you it should be possible to find the pin on the computer that supplies it.
I am no expert on EFI so can`t be of much help there. However there are some real experts on the `87-`96 F-Series page who may help if you post there.

 

Thanks Lazy K, just talking about it with someone seems to help. I will trace the wire back to the ecu on Monday and see if there's a voltage there.
Best regards
Allan

 

You should have the same 5 VDC at the EGR Valve Position Sensor.
The 334 code means the EGR valve is stuck open.

 

Thanks Subford, will check that as well on Monday, did notice that wiring for both do run together over the heads, could be shorting or something.
Best regards
Allan

 

Put 5 hours in and still none the wiser.

The actual TPS is fine, took it off and ran tests on it, works fine.

Of the 3 wires going into it the voltage readings are as follows
vref-5.00v.
sig rtn-0.04v.
tps-0.04v.
If i move the thottle the readings do not change. I followed the sig rtn and tps wires back to the computer and took readings from there and they were the same. As a matter of interest I took readings from the egr valve and they were the same as the readings on the TPS sensor.

Should one of the wires be to earth, I don't understand this at all and really need some help. Please give me any suggestions that you can think of that might help (already thought of the box of matches but I love her to much).

Best regards
Allan

 

Sounds like your tps wire is shorted to ground or to the sig-rtn wire.
The sig-rtn goes to ground (NEG post of battery) after it passes through the computer.

 

Thanks Subford, do you think I should replace wires from computer to thottle and egr, I have done a good serch between the two and cannot see anything that looks suspect? On the wiring diagram in my manual it looks like one of the wires runs to several different sensors.
Best regards
Allan

 

Was the TPS wire at zero volts with the TPS disconnected?
If so that would be OK, you have to check the TPS wire with the TPS plugged in and the key on.
Use an analog VOM and slowly open the throttle with the engine not running.
The needle should go up the scale steady with no drop back or jerks.
If the needle drops back or jerks at any time the TPS is bad.
Note this can not be done with a DMM or DVM.