Gsmblue Posted January 16, 2023 Share Posted January 16, 2023 Ok. Thanks. I will check. But one question...If have the same failure with the original and the 351W ECU...that's a fact that makes me crazy...as also I have changed every involved part... OK... I haven't changed the knock sensor...and also none of the relays...i think more and more that somewhere is a broken wire...but which one can cause such a behavior? Previous owner may have changed the ecu. Link to comment Share on other sites More sharing options...
85lebaront2 Posted January 17, 2023 Share Posted January 17, 2023 Ok. Thanks. I will check. But one question...If have the same failure with the original and the 351W ECU...that's a fact that makes me crazy...as also I have changed every involved part... OK... I haven't changed the knock sensor...and also none of the relays...i think more and more that somewhere is a broken wire...but which one can cause such a behavior? I would suggest (based on my experience with the 1985/86 EFI systems) that you really need to take the wiring harnesses off the EFI system and check for bad sections. I have seen at least 5 of these where the insulation was actually crumbling off the wires leading to shorts. Be especially careful with any shielded wires as the inner insulation may be bad. After 1986, the O2 sensors were changed to heated ones and relocated from the right side exhaust manifold to beyond the point where the two sides of the exhaust join. Link to comment Share on other sites More sharing options...
Gsmblue Posted January 17, 2023 Share Posted January 17, 2023 I would suggest (based on my experience with the 1985/86 EFI systems) that you really need to take the wiring harnesses off the EFI system and check for bad sections. I have seen at least 5 of these where the insulation was actually crumbling off the wires leading to shorts. Be especially careful with any shielded wires as the inner insulation may be bad. After 1986, the O2 sensors were changed to heated ones and relocated from the right side exhaust manifold to beyond the point where the two sides of the exhaust join. If I recall, they made a new harness. It was documented in the other thread Link to comment Share on other sites More sharing options...
ReneH Posted January 17, 2023 Author Share Posted January 17, 2023 I would suggest (based on my experience with the 1985/86 EFI systems) that you really need to take the wiring harnesses off the EFI system and check for bad sections. I have seen at least 5 of these where the insulation was actually crumbling off the wires leading to shorts. Be especially careful with any shielded wires as the inner insulation may be bad. After 1986, the O2 sensors were changed to heated ones and relocated from the right side exhaust manifold to beyond the point where the two sides of the exhaust join. Ok, you are right. There is no other thing that is possible anymore...I have changed everything except the wiring...and I have had to move it while removing the engine. To save time, I will only re-wire the ECU. So I have to check what material I need. I will keep you up to date with pics, so I can show, what I understand as a perfect wiring and routing. BTW...does anybody know where I can buy the connectors for all the sensors? Link to comment Share on other sites More sharing options...
85lebaront2 Posted January 17, 2023 Share Posted January 17, 2023 If I recall, they made a new harness. It was documented in the other thread They did, but from what I read, only part was redone. I was trying to find what I did with the pictures I took of the 1986 harness I sold a while back. It was in two parts, one is strictly the engine portion, the other is the body portion. The body portion goes through the oval grommet to the EEC and EEC power relay. It also connects to the fuel pump relay, solenoid bank and MAP sensor next to the battery, and has the only ground for the entire system as a two pin 1/4" flat blade plug and socket. This is an unsealed connector, attached to the bolt on the negative battery cable clamp. This is one of the problem areas on these as the battery fumes will corrode the connector to the point it has a high enough resistance that the voltages in the system are screwed up relative to ground. If my memory is correct, the right rear intake manifold bolt has a ground wire. Several items in refreshing my memory of these systems. (1) at the test connector (C195) there are 6 holes in it of which 3 are directly concerned with the EFI, 359 (Black with White stripe) is the sensor return to pin #46 of the 1986 EEC, 95 (Tan with Red stripe) is injector bank #2 from pin #59 of the EEC, 96 (Tan with Orange stripe) is injector bank #1. On the wiring diagrams this may be referred to as "used during vehicle assembly". (2) next to the connector is a single Red with White stripe wire, this is called the STI for Self Test Initiate and is used to activate the EEC self test mode (this works on all the EEC-IV systems). With the EEC removed, key on (a) fuel pumps will not run, (b) you should have power on the Tan/Orange and Tan/Red wires. Grounding Tan/Red or Tan/Orange should cause 4 of the injectors to "click", a finger on the ones on the left (driver's) side will confirm which ones Tan/Red should be only the two middle ones (cylinders 6&7), Tan/Orange should be only the two end ones (5&8). If all 4 click, your problem is definitely in the wiring. Link to comment Share on other sites More sharing options...
85lebaront2 Posted January 17, 2023 Share Posted January 17, 2023 Ok, you are right. There is no other thing that is possible anymore...I have changed everything except the wiring...and I have had to move it while removing the engine. To save time, I will only re-wire the ECU. So I have to check what material I need. I will keep you up to date with pics, so I can show, what I understand as a perfect wiring and routing. BTW...does anybody know where I can buy the connectors for all the sensors? There is a Motorcraft connector catalog, and Rock Auto carries some, Amazon carries some and I have a few other sources (one of which is salvaged parts). Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 17, 2023 Share Posted January 17, 2023 There is a Motorcraft connector catalog, and Rock Auto carries some, Amazon carries some and I have a few other sources (one of which is salvaged parts). The catalog is at Documentation/Electrical/Connectors. Link to comment Share on other sites More sharing options...
ReneH Posted January 17, 2023 Author Share Posted January 17, 2023 They did, but from what I read, only part was redone. I was trying to find what I did with the pictures I took of the 1986 harness I sold a while back. It was in two parts, one is strictly the engine portion, the other is the body portion. The body portion goes through the oval grommet to the EEC and EEC power relay. It also connects to the fuel pump relay, solenoid bank and MAP sensor next to the battery, and has the only ground for the entire system as a two pin 1/4" flat blade plug and socket. This is an unsealed connector, attached to the bolt on the negative battery cable clamp. This is one of the problem areas on these as the battery fumes will corrode the connector to the point it has a high enough resistance that the voltages in the system are screwed up relative to ground. If my memory is correct, the right rear intake manifold bolt has a ground wire. Several items in refreshing my memory of these systems. (1) at the test connector (C195) there are 6 holes in it of which 3 are directly concerned with the EFI, 359 (Black with White stripe) is the sensor return to pin #46 of the 1986 EEC, 95 (Tan with Red stripe) is injector bank #2 from pin #59 of the EEC, 96 (Tan with Orange stripe) is injector bank #1. On the wiring diagrams this may be referred to as "used during vehicle assembly". (2) next to the connector is a single Red with White stripe wire, this is called the STI for Self Test Initiate and is used to activate the EEC self test mode (this works on all the EEC-IV systems). With the EEC removed, key on (a) fuel pumps will not run, (b) you should have power on the Tan/Orange and Tan/Red wires. Grounding Tan/Red or Tan/Orange should cause 4 of the injectors to "click", a finger on the ones on the left (driver's) side will confirm which ones Tan/Red should be only the two middle ones (cylinders 6&7), Tan/Orange should be only the two end ones (5&8). If all 4 click, your problem is definitely in the wiring. OK. I will check this. I have made some pictures of the status-quo: My Self-Test-Connector...only 3 cables attached. Is the test you have mentioned possible there? I still don't know for what this connector is... Is this correct? All the fusible-link cables connected to battery +12V? This is the EEC-Power-Realy, as far as I know... For these both I haven't found a counter-part I don't have the climate-system installed, also removed the secondary gas-pump and all EGR-parts...maybe these were for one of them... One of the cables at the connector has no isolation...I know this is GND...but is this "common"? I will come back here, when I have done the tests and started re-wiring. Link to comment Share on other sites More sharing options...
85lebaront2 Posted January 18, 2023 Share Posted January 18, 2023 OK. I will check this. I have made some pictures of the status-quo: My Self-Test-Connector...only 3 cables attached. Is the test you have mentioned possible there? I still don't know for what this connector is... Is this correct? All the fusible-link cables connected to battery +12V? This is the EEC-Power-Realy, as far as I know... For these both I haven't found a counter-part I don't have the climate-system installed, also removed the secondary gas-pump and all EGR-parts...maybe these were for one of them... One of the cables at the connector has no isolation...I know this is GND...but is this "common"? I will come back here, when I have done the tests and started re-wiring. First picture, it looks like your wires are tan/green and tan/red for the injector control. Yes, those are the ones to ground with the EEC removed and key on. Second picture, connector was not used, it may have have been for a not installed option. It is cheaper to build a pretty much "universal" harness. Third picture, definitely looks correct. Fourth picture, that appears to be the fuel pump relay as it is underhood on the driver's side. Power relay should be next to the EEC on it's mounting bracket. Fifth and sixth pictures, again, may have never been connected, particularly the sixth due to the dirt on it. Seventh picture, a bare wire particularly if it is braided is not abnormal in those years. Hope these help. Unfortunately, I will be gone most of tomorrow (US Eastern time 0900-1500) so really won't be able to respond. Link to comment Share on other sites More sharing options...
ReneH Posted January 18, 2023 Author Share Posted January 18, 2023 First picture, it looks like your wires are tan/green and tan/red for the injector control. Yes, those are the ones to ground with the EEC removed and key on. Second picture, connector was not used, it may have have been for a not installed option. It is cheaper to build a pretty much "universal" harness. Third picture, definitely looks correct. Fourth picture, that appears to be the fuel pump relay as it is underhood on the driver's side. Power relay should be next to the EEC on it's mounting bracket. Fifth and sixth pictures, again, may have never been connected, particularly the sixth due to the dirt on it. Seventh picture, a bare wire particularly if it is braided is not abnormal in those years. Hope these help. Unfortunately, I will be gone most of tomorrow (US Eastern time 0900-1500) so really won't be able to respond. Ok. Thanks at all. I will start on Saturday by checking, respectively testing the injectors as you have mentioned. After that, I will un-tape the harness of the ECU and set new cable to it. Independently to the test, the error can also be made by the ECU, based on wrong input data of the sensors, in my opinion. So not only caused on the output side of the ECU, maybe also effected by some inductive or capacitive wrong input... If the harness isn't the problem...I will get mad...it's the last thing I haven't replaced... Link to comment Share on other sites More sharing options...
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