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A. Penland
A. Penland, Ford Senior Master Technician, ASE
Category: Ford
Satisfied Customers: 6667
Experience:  ASE Master Certified, ASE Advanced Gasoline Engine Performance
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I have a problem with 1986 ford F150 5.0 engine. Have tried

Customer Question

I have a problem with 1986 ford F150 5.0 engine. Have tried use innova 3145 OBD1 code reader. All I keep coming up with is 000. I lost the original instructions that were sold with the device. I found instructions online. Somehow I did what the instructions said, which is to warm the engine up then turn it off for 10 seconds. Then plug the device into the unit plug mounted on the truck. Then turn the ignition to on position . Then turn on the unit. So far it just reads 000. I know there is something wrong with the truck because it will miss after warming up and run real rough. It runs smooth cold and rough hot.
I have replaced the rotor, rotor cap, and spark plug wires.

Is anybody out there familiar with this test unit or what maybe wrong with this truck. Any tips anyone has will be deeply appreciated.

Submitted: 7 years ago.
Category: Ford
Expert:  Steve Jensen replied 7 years ago.
While I am not familiar with the scan tool that you are using, it is possible to retrieve the codes using an analog (needle type) voltmeter. It must be a needle type voltmeter, a digital is just too difficult to follow the pulses. Use the meter on a range that will read 12 volts. 1st, looking at the self test connector the top two terminals are number 1 and 2, reading from left to right. The bottom four terminals are 3,4,5 and 6 reading left to right. Jumper the self test input lead (the separate lead next to the self test connector) to terminal # XXXXX then connect the voltmeter positive lead to the battery positive terminal, connect the negative lead to the #4 terminal on the self test connector. Turn the key on, after a short delay, the needle on the voltmeter will begin to sweep across the meter and back to zero. It will do this a number of times. You'll count each sweep as they occur, then there will be a slight delay of about 1 second, then some more sweeps. The first sweeps plus the second sweeps are a code. For example, sweep, sweep, sweep, delay, sweep, sweep would be read as a code 32. These are hard fault codes, problems the computer sees right now. You may receive several different codes one right after the other. After the first codes, there will be a longer delay, then one sweep of the meter. This is a separator code. Other codes will occur after the separator code, these are memory codes. Don't worry about missing any, you can leave the jumpers connected and the series will repeat (hard faults, separator, memory codes). Shut the key off after you have read the codes, disconnect the jumpers only after the key is off or you lose the memory codes. You can also perform an engine running test by warming the engine up and running it at 2000 rpms for 2 minutes. Then connect the jumper, restart the engine. You'll receive four sweeps of the meter indicating an 8 cylinder engine, then the codes will be output about 60 to 120 seconds later. Hope this is of help to you, hard to find diagnostic testers to work with these old EEC IV systems anymore. A diagram of the self test connector and jumpers is below. Steve
Expert:  Steve Jensen replied 7 years ago.
Customer: replied 7 years ago.

Can you suggest what might be the problem? Why it might run smooth cold, but run rough hot. After driving it a couple of miles it starts to sputter and loose power. I drove it up to the gas station which is a couple of miles from my house. I got there fine after turning the truck off and pumping gas into the tank. Driving out of the station was really rough and I barely made it home. I need to know what to check next. Could spark plugs be the culpret?


I'm thinking possibly the pressure regulater valve since it is a fuel injection engine. I'm not real familliar with this type of engine as far as trying to repair it.

Expert:  Steve Jensen replied 7 years ago.

There are quite a number of possibilities, but without some diagnostics being done it is very difficult to recommend anything beyond the things you have already tried. Since you state that you have already changed the spark plugs then I would not recommend changing them again. I will opt out and allow other experts to review your question and offer suggestions. Thanks, Steve

Customer: replied 7 years ago.
found out what I did wrong with the OBD1 tester I finally got results with it. It is showing numbers 11 for pass, 18 for ignition diagnostic monitor (IDM) circuit failure, and for some reason it is showing number 10 for results. Can you tell me if the IDM is located under the hood of the truck and if so where? or is it located under the dash.
Expert:  A. Penland replied 7 years ago.


The code 18 is for the TFI module mounted on the side of the distributor. Replace the Module and I would also recommend replacing the stator inside the distributor. We always recommend replacing these two items together. The distributor will have to be removed to replace the stator inside the distributor. This module controls the spark for your engine.

Customer: replied 7 years ago.
I have replaced the TFI module before I got your answer, no change in status. Upon removing the distributor cap I only noticed a round disk like object on the bottom inside the distributor around the dist shaft.
This disk has a slot in it that anchors the rotor. Referring to my Haynes Ford Pick-Up 1980 thru 1996 auto repair manual, Page 5-14---5-15 describes and displays the distributor. However, the distributor shown here is different from the on that has been in this truck for the 7 years I have owned it. Could there be some difference? The top of this
distributor seems to be considerably larger than the one displayed in the picture. The metal base of the distributor says Motorcraft E4ZE* 12131AA. There seems to be no stator assembly in this distributor as described in the manual. I am puzzled. Could this be a different design?
If so is there something that replaces the stator differently? Trust me nothing has been removed from this dist. This truck has been running perfect for the past 7 years. Please advise.
Expert:  A. Penland replied 7 years ago.

Sorry I'm a little late.

The Haynes manual is generic for Ford. If you have a TFI module mounted to the side of the distributor, you have a stator inside. It is the trigger wheel that tells the ECU where cylinder #1 is and fires the spark plugs in the proper firing order. Replace the stator and your truck should run properly.

A. Penland, Ford Senior Master Technician, ASE
Category: Ford
Satisfied Customers: 6667
Experience: ASE Master Certified, ASE Advanced Gasoline Engine Performance
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