Hello all,

This is my first post. I found this forum as I was searching for diagnostic information. The first few pages of threads had some discussions that seemed to indicate this forum was active in diagnostics, so I registered and performed a number of searches before posting this thread.

I'm hopeful you will be able to confirm my diagnosis or suggest alternative tests or solutions on a troubled vehicle I have been asked to look at.

My neighbor brought me his 3/1995 F250 4wd with the 5.8L EFI and E4OD trans. It is very sick and presents the following symptoms:

* The air intake must be blocked to start the engine cold. Starts OK warm.
* Rolls black smoke out the tail pipe. Mileage is terrible and lacks power.
* MIL is lit constant.
* Does not take throttle well but will accelerate if throttle is opened slowly.
* Fuel pump runs KOEO (is this normal???)
* No communications with scanner

I have looked the truck over and performed a basic inspection:

* Charging system and battery OK at 14.2v. No A/C voltage leaking through.
* All fuses under the hood and in the lower dash panel check good.
* Wiring, vacuum hoses and all connections appear intact. (the vehicle went to a shop before he brought it to me. Sometimes things are left undone)
* Engine vacuum is a steady 18" at idle and does not fall below 15" if throttle is opened slowly. Sudden accell causes a drop below 15" as the engine bogs down and dies out.
* I do not have a fuel pressure tester to fit a schraeder valve, but please read on...


I installed a breakout box and pinned out the computer. All power and grounds check out. Most sensor outputs and inputs were in or very close to range. HOWEVER......

* Both injector banks (pins 58 & 59) receive VBAT KOER. My info says the injectors should see VBAT at KOEO only???? I think I found the source of fuel flooding!
* HO2S (pin 29) is .92v fixed..... no duh. See above point and lets hope the sensor works after fuel is back in control.
* Fuel Pump Enable (pin 22) is .15v KOEO. My info says it should be VBAT???
* Fuel Pump Monitor (pin 8) is VBAT KOEO. My info says it should be 0v???
* Trans Shift solenoid (pin 52) reads VBAT. My info says .2-.8v KOEO and KOER???
* Trans Electronic Pressure Control (pin 38) reads VBAT. My info says 6.6-10.4v KOEO or 8.3-12v KOER???
* MAP (pin 45) reads 158hz KOEO and 116hz KOER (close enough)

Gentleman, I believe I have a bad computer to replace. It appears the Computer's Injector, Fuel Pump and Transmission Solenoid circuits are inoperative, and not responding to changes in running status.
Before I take the next step, I am appealing to y'all to see if my information and conclusions are correct. Have you ever seen or heard of a failure of this nature? In my thinking the circuits that are inoperative are some of the biggies, in that they need big drivers to switch. On the other hand, wouldn't drivers fail and leave the circuit open?

I am at the end of my understanding about this truck. I appreciate your patience and assistance with this project and the puzzle it presents. Thanks!

Rick

 

Yes you are right, you have a bad computer.
The pumps should only run for one second when the key is turned on.

 

Thanks for the quick response. Do you happen to have experience with this failure or any insight on the other issues, ie injector voltage and the transmission solenoid voltages?

I am wondering if any of you all have seen many Ford truck computer failures?

Also, are there resources for computer testing and repair other than the dealer?

Thanks,
Rick

 

Have seen the fuel pumps run all the time with no communications with scanner and if the computer has battery voltage at the right pins with the key on (pins 1, 37 & 57) and gorund on pins 40 & 60 then a replacement computer has always fixed this problem. But most of the time the engine will not start either when this happens, no injector grounding by the computer.

This one sounds like the computer is running in limp mode. Do not know if the pumps run all the time in limp mode or not but you should have communications with scanner.
The injectors should have VBAT on them (red wire) all the time the key is on.

All the sensor and solenoid voltages being off most of the time is also a bad computer but these voltages may do this also in limp mode. Pin 52 should have battery voltage on it all the time the key is on and the truck is not moving or in 1st gear, Pin 52 is shift solenoid #2.

We see them failing on here about two times a week but we are talking about a lot of postings.

Yes, I see them mentioned on here from time to time but have never book marked them. I remember one in Minnesota and one the other day in Florida was posting on here. I do not think you are going to find a Dealer to repair one or test it. Most auto parts stores will sell you one but I get mine from salvage yards or truck that I have parted out.

 

Bill and all,

Thank you for your patience as I learn my way through this puzzle. I made two new discoveries that have me feeling fairly certain about what there is to do:

First, I remeasured the injectors correctly by switching my meter to read in mili-seconds during idle. I read 2.1ms at idle, which is way below spec, but.......

Second, I remeasured the crank angle sensor, SPOUT and IGN Diagnostic readings after performing maintenance on my Fluke meter LCD connections. I now have a readable readout and discovered the computer is seeing 7990 rpm at idle!!! Moral: Keep your tools in good order and never assume!

Based on these findings, I now believe that I need a crank angle sensor to correct the fuel delivery. My thinking is that the computer is working off a false crank signal that is about 10x reality.

At the same time it needs a replacement computer to correct the fuel pump, MIL and diagnostic link functions. BTW, all rpm signals do read zero at KOEO.

One more observation with a question: The E4OD wire plug on the passenger side of the transmission is completely melted and has exposed connection wires and pins. In your experience is this damage from exhaust radiated heat, a transmission overheat or from a grass fire underneath the truck???

EDIT: I used the search routine on this forum as a component locater and discovered the pulse generator is in the dizzy and the control module is hanging like a bat under the left hood hinge, near the SPOUT connector. Does anyone have directions to a component test procedure to diagnose a faulty PIP signal???

Needless to say, I'll be addressing this issue when it's time to commence repairs!

Thanks,

Rick

 

I think I would fix the plug on the transmission first and then check the ICM to make sure it is black in color. A Gray one will not work well in a 1994.
I am not convinced that there is anything wrong with the computer at this point.
As long as it is running I would not worry about the PIP sensor or its pulses at this point.
If the injector pulse is short it should not be running rich unless the fuel pressure is out of site. Should be about 32 PSI at idle with a good vacuum.

Why not give up on the scanner (not sure what you have for a scanner) at this point and try grounding the STI wire and see what the MIL does.

 

Bill, I need to take baby steps here. ICM = Ignition Control Module??? Color coding is the molded wire surround like the ancient ford modules before computer controls?? Please elaborate. BTW, truck is 03/95 Fed w/auto.

I agree and am not going to brief my neighbor until I have something approaching certainty. However, I envision a possible scenario as described below.

If the PIP sensor or ICM is sending the computer a 10x signal, I believe it is likely for the computer to set the MIL and lower the injector pulse width. My current thinking is that even a low pulse width is gonna add too much fuel if the computer is firing off the injectors at 10x actual engine speed. What are your thoughts on this?

I will do that. Please describe the location and usage of the STI. I imaging it will flash the MIL, is that correct? Also, I'll need to know where to obtain a table for decoding the stored codes.

Thank you Bill,

Rick

 

if you remove the pcm open it up and look at the board to see if it burned. ive had 2 of my trucks computers fail. they all had burn marks at the 3 blue capacitors that are in there.

 

Great info here: Ford Fuel Injection

 

Thanks for the idea. I will definitely open up the PCM if I get to the point where replacement is required. Given all the big current items are whacky: (injectors, fuel pump, trans solenoids) it would not surprise me to find a crispy quad driver or two.

Rick

 

Man, thanks! That is EXACTLY what I am needing. I found the info on extracting codes and will employ the test light method. Awesome!!!

I live in a remote area and the internet and these forum communities are vitally important to my family and neighbors. I am a Toyota Landcruiser guy floundering my way through Ford land and I could not succeed without you!

Thanks again to you and everyone for guiding me through this process.

Cheers,

Rick

 

Yes ICM = Ignition Control Module.
TFI = a type of ICM.


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Bill,

Thanks for the explanation. I stood on my head and read the PN, which is non of those listed on your image. I did not see the hall effect connector.

Question: could a loose or worn distributor bushing cause a rattle or vibration in the pickup, making multiple trigger signals? I do not have access to a lab scope, so I seek your advise on alternative test measures.

Rick

My next investigation will be to see if I can get codes out without using the scanner.

 

The above Ford numbers are part numbers.
Ford never puts the part number on a part as it changes.
The numbers you see on a part are drawing numbers.
The number on a part will not have the "Z" in them as the part number does.
The number that everybody (auto part stores, salvage yards and the net) goes by but the Ford dealers on the computer is the drawing number.
Ford dealers can cross the drawing number to the current part number.

No I do not see any way a rattle or vibration in the pickup stator can make multiple trigger signals.
There is no coil in the pick up PIP sensor mount on (in) the stator assembly inside the distributor.
To replace the PIP sensor you replace the stator assembly.
But the Distributor has to be taken out of the engine and tore all the way down to replace the stator assembly.

PIP: Profile Ignition Pickup.

For more information on the GRAY vs BLACK ICM read the article titled:
DOMESTICALLY SPEAKING
in this link.
http://www.capitolautomotive.com/pdf/cccnewsletter.pdf

For more information on the PIP read about it in these two links:
http://www.wellsve.com/sft503/counterp_v8_i2_2004.pdf
AND
http://www.wellsve.com/sft503/counterp_v8_i3_2004.pdf

What a PIP sensor is and one way I tested one on the bench while turning the distributor.



/

 

Bill, thank you for the information and links to these articles. The explanation of the two modules was informative. BTW, the link to part 1 of the 2 part article did not work, but I got the gist of the complaint and cause from the second part.

I was unable to get codes manually from the PCM. The out put terminal is constantly grounded, with key off or on.

I agreed earlier to take your advise and to defer on the PIP and SPOUT measurements, since the motor runs. It is entirely possible that I do not have sufficient experience with my meter, and have made errant measurements. If true, then I am left with:

* A vehicle that will crank but won't start cold (without blocking the intake)
* Fuel pump(s) run constant KOEO
* MIL lit, and no way to access codes

As you indicated earlier, these symptoms point towards a computer failure. Since I have no further ideas to explore or tests to eliminate external influences, I'll recommend a replacement computer to my neighbor.

If he accepts my theory and recommendation, I will access his computer before replacing it to perform a careful visual of the internal.

I'll let you know what I find!

Thank you,

Rick