Ok Gents, here's my delema.

1992 F350 4x4, 5 spd, 7.5. Had major wiring issues. would start, but ran extremely rich(enough to buirn your eyes). Code reader would not communicate with the computer. removed engine harnesses and repaired and rang them out. Allseems fine. opened EEC lid, no smoked components. Engine light stays on. Truck starts, idles fine, just very rich. Fuel press reg diaphram os ok, havent checked fuel pressure yet. Code reader will only initiate the self test if connector is installed upside down??? Pin out is correct by all available data, reader shows 000 for codes. changed the following: Plugs, wires cap , rotor, fuel filter, no return line obstructions. Revvs up fine. Heres my to-do list:Check fuel pressure and leak down rate, initiate test mode with jumper instead of reader, Verify base timing. ANy other suggestons??? No cats, planning on removing air pump. EGR seems to work fine. FUN!!!

 

Do the fuel pumps also run all the time the key is on and the engine is not running?
If so the computer is bad.

 

I have removed the front tank and pupmp assy for replacement. The rear comes on momentarily and then shuts back down, as it should. Going to check may ECT, MAP sensors and fuel pressure tonight , I hope.

 

The computer should run the self test by grounding the STI wire and turning on the key.
Then the MIL will flash the codes.

 

I printed off the instructions from fordfuelinjection.com and will be trying it tonoght.

 

OK, Got the initial timing set. It was off, running around 15 deg. Set back to 10, hooked in Spout and timiing jumped to about 20 ish like it was supposed to. Fuel Pressure is 38 KOEO, and 32 running. Drops off fast down to 20 within 1 min when shut down. Leaky injectors? Im thinking fuel pump check valve. I have true duals and the injectors would have to be leaking on both sides to make em smoke like that. Possibility though....

The code reader would work, Jumped the sig in to gnd, got codes 22, 35, 51, 53, and 54 both on KOEO and CM modes. Didi not run KOER test yet.

All codes but 22 point to too high voltage, but KOEO v-batt is 4.87 at all 5 sensors (MAP, ECT, EVP, TPS and ACT) Is it possible all are bad????

Why would the voltage read too high? EEC volt reg fail?

FUn , FUn, FUn!!!

 

I take it you mean VREF not v-batt.
4.87 sounds a little low for VREF.
But you are saying all errors are to high.
Check and make sure the computer has a good ground.
I would not think you have any bad sensors.
You might try unhooking the battery for about 30 minutes so the computer can read new sensor values. Then see what you have.

 

Had a good evening to work on the truck last night.

Here's the play by play. Had battery disconnected previous day. STarted truck up to temp and ran KOEO sefl-test, got codes 22, 35, 51, 53, 54. Exact same codes presented for CM test. Ran the KOER test got codes 98, 22, 54, 51, 53. All codes say sensors reading above max voltage, except MAP (22) which delivers freq to ECC and was out of range. KOER code 98 was new, hard fault present (not a good code to get).
Pulled all sensor connectors and and o2 sensor conn C103. On grey/red wire (signal return) got 5v at all connectors and at C101 and self-test connector, weird.... Checked Br/wt wire at EVP, TPS and MAP and got 4.99v. ECT and ACT sensor lg/r and gy colored respectively ( signal to ecc wires) read at 4.61v.(weird again...). EVP wire bk/y read at 8.73v!!!, So basically i am getting voltage sent from the ecc to all the sensors on all wires! Not good..... These values are made to ground point G101, with KOEO. DIsconnected C101 connector, still have 5v at grey/red wire(sig rtn) on ECC side of harness and at all sensor signal return wires to ecc. DIscommected harness from firewall and ecc, opened it back up and re-traced all sensor , vrf and sir rtn wires. all rang out under .4 ohm, no fraying all good at connectors.
Rang out the case ground pin on the ecc was good, good grounds through entire harness. WHy is my ecc delivering voltage on all pins, My vote is it is fried. There is no visible damage to it, once opened up. But guven the hard fault code 98, I'm leaning towards getting a new one. AZ has it for $188. pn F2TF-12A650-KA.
Does it sound to you loke I am going down the right path? With the wiring issues that I have repaired so far, I have no tdoubt that ECC damage could have occured.

Sorry for the LONG post , but maybe this can help others with similar issues too ......... Thanks for any and all help! Especially you Subford!

 

The hard fault code 98 means the computer is running in limp mode. Hard fault code 98 will have another code along with it causing the hard fault code 98.

Hard codes are the ones you see with the KOEO self-test. The KOEO is an electrical test of the sensors and relays.
CM are the codes you get while running on the highways.
KOER self-test is a test of the solenoids.

Do not take them your core PCM until you see what the replacement computer acts like. It could be worse then yours but if it gives the same codes I would put your old one back in.

 

The KOER test codes were 98, 22, 54, 51, 53. Other than the hard fault code, all others were the same sensor volt high codes (MAp out). Why would the computer give me positive voltage at the signal return lines from the sensors???? This is the primary reason I think the ECC is faulty.
Would I be able to use any 7.5L F2TF-xx ECC to try and run the engine? Like one out of a van? Mine is JUST for 7.5 , 5spd, 250&350 with the -KA code. Like trying to find a needle in the haystack for a used one.
What specifically makes you think the ECC is not at fault?

Thanks!!!!!!

 

Sounds like the SIG GND has lost its path back to the computer.



/

 

This is the internal of the EEC? With EEC out, Case gnd reads zero ohm from pin 20 to external case. The signal return wire from EEC connector pin 46 to the engine harness break at C101 and SIG RTN at Self Test conn, are physcially intact and read 0 ohm between each point. When the EEC connected, and with the engine harness disconnected at C101 (60 pin square connector inboard of Power dist box) and O2 conector disconnected, Key on, the computer is producing 4.87v from pin 46, 45, 7, and 25. 4.99v@ pin 26, and 8.7v @ 27. 0.0v @ 47.
I will need to check resisatnce values between 46, 40 , and 60. Shoould all be zero ohm correct? Do you have more on the internal EEC schematics? J! 62 and J1 63 (CONN. MTG HOLE) I assume is the threaded bolt hole for the connector attachment to the EEC? Thanks for the brain-work!

 

Yes it is.

It should be zero.


I do not know if you are talking computer pin numbers or C101 pin numbers.
But all the three wire sensors when back probed should have near 5.0 VDC on the V REF pin and zero volts on the SIG GND pin (EVP, TPS & MAP).


Yes, zero.


I only have the one that is on the internet. I do not know the year the EEC schematic goes to.
If you want I can email it to you if you can not find it. Just email me you email address.
If I posted it you would not be able to read it. My email address is at the bottom of my posts.


I do not find the schematic to be right on the J1 62 and J1 63 (CONN. MTG HOLE). It is open to all other pins when I check the computers I have. It may be right on some other computers.

 

Your quote:

"I do not know if you are talking computer pin numbers or C101 pin numbers.
But all the three wire sensors when back probed should have near 5.0 VDC on the V REF pin and zero volts on the SIG GND pin (EVP, TPS & MAP). "

I am referencing EEC pin numbers. V-REF at the sensors is 4.99v this is the brn/wt wire from EEC pin # 26. The SIG GND (on my chart as SIG RTN) Reads at 5v from the disconnect at the C101 connector Gray/red wire from the EEC pin # 46(shown by eec schem as a GND). I am 99% sure I checked eec pins 40 & 60 and they had zero Ohm not sure about 46 to 40 & 60. EEC connector pins40& 60 larger blk/wt wires ring out to ground points Ok with eec disconnected.

Found an EEC schematic that has the same section that you posted. I see in the schematic that EEC pins 7, 25 and 47 have a 5v source ti their processor chip. If the chip fails or loses its ground, would the 5v not back feed into the sensors(ACT, ECT, and TP)? but I still am getting 5v at eec pin 26 as an isolated EEC pin.

 

If SIG RTN is floating (C101 disconnected) it would have about 5 VDC on it also.
This wire has to be zero volts (grounded) for the sensors to send back the right value.
But if C101 is disconnected you would not have 5 Volts on any of the sensor wires anyway.

If a chip shorts it will blow apart most of the time and will not back feed any voltage.