ratdude747 Posted February 24, 2021 Author Share Posted February 24, 2021 Oh no! Hope it was a fluke. It wasn't... did it again this morning (rough fluctuating idle, 6 degrees of timing). Pulled codes, no codes, all good. Tried to erase codes... no change, still 6 degrees of timing. Drove it to work... when I got to the lot, re-timed it at warm idle, back to the expected 30 degrees (or wherever it's been idling at when good). Seems 6 degrees isn't necessarily an indication of limp mode... could it have had to do with being on the fast idle cam? I didn't take it off the cam until I drove it to work. Will recheck the schematics on site to make sure there isn't an extra input or the like used by manuals... Weird indeed. Considering it's a Ford reman, my thinking is it was actually remanned. Maybe I ought to pop it open and check for any blown caps... it came in a very old box! Link to comment Share on other sites More sharing options...
ratdude747 Posted February 24, 2021 Author Share Posted February 24, 2021 Oh no! Hope it was a fluke. It wasn't... did it again this morning (rough fluctuating idle, 6 degrees of timing). Pulled codes, no codes, all good. Tried to erase codes... no change, still 6 degrees of timing. Drove it to work... when I got to the lot, re-timed it at warm idle, back to the expected 30 degrees (or wherever it's been idling at when good). Seems 6 degrees isn't necessarily an indication of limp mode... could it have had to do with being on the fast idle cam? I didn't take it off the cam until I drove it to work. Will recheck the schematics on site to make sure there isn't an extra input or the like used by manuals... Weird indeed. Considering it's a Ford reman, my thinking is it was actually remanned. Maybe I ought to pop it open and check for any blown caps... it came in a very old box! Looking at the wiring diagram, there is one ECU wire marked "auto trans only"... it connects to a diode, which connects to the ECU and one wire on the EEC IV test connector. tracing it back, it goes to the middle of the neutral/clutch starter interlocks in the cranking circuit... but due to how the diode is wired, all it seems to do is allow one to crank the engine from the test connector (blocks the cranking power from making it to the test connector and ECU). Unless this is a misprint, that effectively means that for ECU operational purposes, it doesn't matter. However, if that diode was shorted... trouble. Not sure what that wire does on the test connector (dark green and white), but if that was kicking on every time I started, could it be putting me in some sort of weird test mode? Thankfully, since it is on the test connector, and that the starter relay control wire is close by, testing for a shorted diode is easy and I'll try to check it after lunch. Edit- that wire goes to pin 5 of the test connector... which everywhere seems to be "unused". So what it does, nobody knows? Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 24, 2021 Share Posted February 24, 2021 Looking at the wiring diagram, there is one ECU wire marked "auto trans only"... it connects to a diode, which connects to the ECU and one wire on the EEC IV test connector. tracing it back, it goes to the middle of the neutral/clutch starter interlocks in the cranking circuit... but due to how the diode is wired, all it seems to do is allow one to crank the engine from the test connector (blocks the cranking power from making it to the test connector and ECU). Unless this is a misprint, that effectively means that for ECU operational purposes, it doesn't matter. However, if that diode was shorted... trouble. Not sure what that wire does on the test connector (dark green and white), but if that was kicking on every time I started, could it be putting me in some sort of weird test mode? Thankfully, since it is on the test connector, and that the starter relay control wire is close by, testing for a shorted diode is easy and I'll try to check it after lunch. Edit- that wire goes to pin 5 of the test connector... which everywhere seems to be "unused". So what it does, nobody knows? I don't have the '84 EVTM to-hand, but looking at the '85 version on line I see the W/PK Dot wire as shown below. Is that the one you are talking about? Man, it gets confusing after that. Towards the bottom of the page is says those wires go to pages 28 and 31. Here is Pg 28 and I can't find that wire. However, the circuit that wire is part of does come back to this page from Pg 31 at M. And here is Pg 31. This time the wire is shown, but it is labeled "EFI Only". Do these pages match yours? If so, it appears that the wire is there to tell the ECU that the tranny is in Park or Neutral and it is safe to crank the engine. Link to comment Share on other sites More sharing options...
ratdude747 Posted February 24, 2021 Author Share Posted February 24, 2021 I don't have the '84 EVTM to-hand, but looking at the '85 version on line I see the W/PK Dot wire as shown below. Is that the one you are talking about? Man, it gets confusing after that. Towards the bottom of the page is says those wires go to pages 28 and 31. Here is Pg 28 and I can't find that wire. However, the circuit that wire is part of does come back to this page from Pg 31 at M. And here is Pg 31. This time the wire is shown, but it is labeled "EFI Only". Do these pages match yours? If so, it appears that the wire is there to tell the ECU that the tranny is in Park or Neutral and it is safe to crank the engine. Yeah, that's the wire on the other side of the diode. The wiring diagram I'm looking at goes like this: Green is the ECU wire, 150. This one makes it sound like that wire goes to the connector (to the "5" position, which from what I read elsewhere is universally "unused" across all EECIV???) Diode is in yellow. The white/pink crank wire, 33, is in magenta... which follows along to this page: ...which matches what the EVTM is showing. I've crossed out the unused duraspark system shown on this page. Based on the diode polarity, for an automatic, if there wasn't a connection to the test connector, unless the ECU was somehow commanding crank (obviously not!), that wire would do nothing, as the source is either open or +12V (no ground for current to sink to). Which is what makes me think that both options have the wire to the connector, and it was used for a Ford proprietary purpouse (why it's listed as unused), which on automatics also serve to crank the engine over if the transmission is in neutral/park. I'll look into it over lunch (and if the connection does exist to the test plug, I can diode test between it and the solenoid command wire both ways to see if the diode is shorted). Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 24, 2021 Share Posted February 24, 2021 Yeah, that's the wire on the other side of the diode. The wiring diagram I'm looking at goes like this: Green is the ECU wire, 150. This one makes it sound like that wire goes to the connector (to the "5" position, which from what I read elsewhere is universally "unused" across all EECIV???) Diode is in yellow. The white/pink crank wire, 33, is in magenta... which follows along to this page: ...which matches what the EVTM is showing. I've crossed out the unused duraspark system shown on this page. Based on the diode polarity, for an automatic, if there wasn't a connection to the test connector, unless the ECU was somehow commanding crank (obviously not!), that wire would do nothing, as the source is either open or +12V (no ground for current to sink to). Which is what makes me think that both options have the wire to the connector, and it was used for a Ford proprietary purpouse (why it's listed as unused), which on automatics also serve to crank the engine over if the transmission is in neutral/park. I'll look into it over lunch (and if the connection does exist to the test plug, I can diode test between it and the solenoid command wire both ways to see if the diode is shorted). I know there are several connections shown in the EVTMs that were for factory use only. So maybe that is one of them? Anyway, good luck! Link to comment Share on other sites More sharing options...
Tyler Posted February 27, 2021 Share Posted February 27, 2021 I know there are several connections shown in the EVTMs that were for factory use only. So maybe that is one of them? Anyway, good luck! I haven't read the 20 pages....just getting home from a little trip out in the deep ocean. Looks like you've found some problems but did you consider a clogged catalytic converter? I went to an old timer shop years ago with stalling problems and they cut a hole in my cat. Got a history lecture about clogged cats and automatic old Fords. Drove away a little louder but it fixed my issues. Cheers Link to comment Share on other sites More sharing options...
ratdude747 Posted September 19, 2021 Author Share Posted September 19, 2021 I haven't read the 20 pages....just getting home from a little trip out in the deep ocean. Looks like you've found some problems but did you consider a clogged catalytic converter? I went to an old timer shop years ago with stalling problems and they cut a hole in my cat. Got a history lecture about clogged cats and automatic old Fords. Drove away a little louder but it fixed my issues. Cheers Reviving this thread to put it to bed once and for all. Two final changes were made which seemed to fix the problems: 1. I replaced the catback. See this thread for details. My muffler was a very, very, very poorly flowing unit to say the least... That had a huge impact on MPG (or at least has on the limited testing done so far). 2. While on one of many junkyard runs due to an unfortunate incident, I picked up another 1984 300 AOD ECU... and have ran it for a day of mixed driving with no issues. And compared to the manual ECU, the only difference that I might have noticed is the idle speed (but that's hard to say, since most of what I saw was related to the fast idle cam, not the ECU throttle control). I ran KOEO and KOER tests and other than two faults on the latter for not kicking the throttle in time (and having a testing failure preventing a retest). Problem solved. Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 20, 2021 Share Posted September 20, 2021 Reviving this thread to put it to bed once and for all. Two final changes were made which seemed to fix the problems: 1. I replaced the catback. See this thread for details. My muffler was a very, very, very poorly flowing unit to say the least... That had a huge impact on MPG (or at least has on the limited testing done so far). 2. While on one of many junkyard runs due to an unfortunate incident, I picked up another 1984 300 AOD ECU... and have ran it for a day of mixed driving with no issues. And compared to the manual ECU, the only difference that I might have noticed is the idle speed (but that's hard to say, since most of what I saw was related to the fast idle cam, not the ECU throttle control). I ran KOEO and KOER tests and other than two faults on the latter for not kicking the throttle in time (and having a testing failure preventing a retest). Problem solved. Glad you got to close this out, Larry. Link to comment Share on other sites More sharing options...
ratdude747 Posted October 11, 2021 Author Share Posted October 11, 2021 Glad you got to close this out, Larry. More data from a long trip in it: Mixed highway with a bit of local driving: 16mpg Pure interstate 70mph: 18.4mpg. Link to comment Share on other sites More sharing options...
Gary Lewis Posted October 11, 2021 Share Posted October 11, 2021 More data from a long trip in it: Mixed highway with a bit of local driving: 16mpg Pure interstate 70mph: 18.4mpg. That’s good MPH. Link to comment Share on other sites More sharing options...
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