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Thread: DIS Conversion Issues

  1. #1
    Join Date
    Aug 2019
    Location
    Southern Utah
    Posts
    3

    Default DIS Conversion Issues

    To start with some background, I've got a Windsor based SBF installed in a '67 Fairlane, backed by a T56 Magnum manual transmission. (306 CI, AFR 165 heads, Explorer GT40 intake, Holley 30lb injectors, and a Comp 290HR cam) About 2 years ago, I converted the engine over from a carburetor to a Dominator driven sequential EFI, using Ford TFI ignition. I have about 23,000 miles on the engine since the EFI conversion. About a month and a half ago, the TFI distributor had a failure of the plastic that holds the in-distributor sensor in location, and the car stalled, leaving me stranded about 400 miles from home.

    I was planning on upgrading to a Distributorless Ignition system soon, so I pulled the trigger and began that upgrade. (Also, it's worth noting that I'm a harness designer for a small aerospace company, and I've designed and fabricated my entire harness for the EFI and under-hood chassis harness to those aerospace standards, using a combination of aerospace connectors and OEM automotive connectors. All my wires are white, with functions printed on them. There are no Holley harnesses under my hood, with the exception of the WBO2 sensor.)

    That brings me to the current ignition setup:
    eBay grade GM D585 truck coils, installed on the shock/spring towers of my Fairlane.
    Stock '98 Ford Explorer cam synchronizer (Hall-Effect).
    DIYAutotune Hall-Effect crank sensor.
    36-1 trigger wheel.

    I've installed the crank sensor such that the centerline of the sensor is located approximately at the trailing edge of the 6th tooth after the missing tooth of the 36-1 trigger wheel. (It's the tooth that worked out best for my physical installation, and my tune is only running about 50° of timing max at light cruise anyways.)




    (All images at TDC.)

    I have installed the cam syncronizer such that the Hall-Effect sensor is reading the falling edge of the half-moon trigger wheel when the crank is at approximately 195° (or halfway between the 25th and 26th tooth after the missing tooth), per the instructions here. (I also, just for kicks, attempted to install the falling edge of the cam sensor 195° before the 6th tooth on the trigger wheel, but with the sensor in this position, the engine won't even start, just coughs and sputters.)



    (Images on the 25.5 tooth counterclockwise/after the missing tooth on the trigger wheel.)

    The problem that I'm having is that, while the engine does start, it's running very rough, I'm hearing and feeling a knock, and it's backfiring quite a lot as well (perhaps 1 or 2 backfires every few seconds). Additionally, when it is running, the exhaust fumes are very strong indeed, and are making my eyes and throat burn (this is not normal for my tune, it used to be just fine).

    If I increase the TDC tooth number in the software, the backfiring reduces (at TDC tooth #8, the backfiring is more-or-less eliminated, though the rough running and "knocking" sound continues. exhaust fumes also get significantly improved, though still worse than when it was on the old TFI ignition system.

    Also, at TDC tooth 7, when I check the ignition timing with a light, the ignition timing is only about 4° retarded from the commanded timing in the ECU (IE: ECU commands 25, the light is firing at about 19°)
    At TDC tooth 6 and a commanded timing of 25, the actual timing is more like 32°.
    When I have the TDC tooth set to 6, and I then set the timing offset to -6, then the commanded timing matches the actual timing to within ±1° at idle, though the knocking, backfiring, and fumes remain.

    I suppose my real question then, is why might the engine appear to run better if I increase the tooth number in the ECU, even though the sensor is physically installed to look at the 6th tooth?

    As far as diagnostics go, this is what I have already looked at and done: Prior to even starting the engine for the first time, I verified the coil wiring by checking continuity throughout my harness that my pins for the coil trigger wires are as follows:

    Wire Name ECU Conn ECU Pin Coil Location Coil Pin
    EFI EST CYL1 COIL 20
    J1B
    B21
    Cylinder 1
    C
    EFI EST CYL2 COIL 20
    J1B
    B15
    Cylinder 2
    C
    EFI EST CYL3 COIL 20
    J1B
    B22
    Cylinder 3
    C
    EFI EST CYL4 COIL 20
    J1B
    B16
    Cylinder 4
    C
    EFI EST CYL5 COIL 20
    J1B
    B23
    Cylinder 5
    C
    EFI EST CYL6 COIL 20
    J1B
    B17
    Cylinder 6
    C
    EFI EST CYL7 COIL 20
    J1B
    B24
    Cylinder 7
    C
    EFI EST CYL8 COIL 20
    J1B
    B18
    Cylinder 8
    C

    (The coil pin numbers are per this link. IE:
    A = Chassis Ground near coil
    B = ECU connector J1B, pin B14 (ground)
    C = ECU EST pin for the cylinder
    D = Relay triggered key on +12V

    I also verified by continuity that the Crank and Cam sensors are wired as follows: (Note: The shield drains for the sensor wires are daisy chained right near the ECU, with only about 1-2 inches of unshielded cable, while the drain wire itself is perhaps 5 inches long. Also, I'm using aerospace grade M27500 type cable, which has a woven braid for the shield, and I'm using M83519 solder sleeves to terminate the woven braid to a 22 awg wire.
    I've also spliced the 12V for the cam and crank sensor together out near the sensors themselves, since I was originally going to use a VR type sensor, but it was being a mega PITA)
    Wire Name ECU Connector ECU Pin Sensor Sensor Wire
    EFI CAM SENS SHIELD 22 J2B B14 Cam Sensor FLOATING
    EFI CAM SENS SIG 22 J1A A22 Cam Sensor 2
    EFI CAM SENS REF GND 20 J1A A14 Cam Sensor 1
    EFI CAM SENS 12V 20 J2B B20 Cam Sensor 3
    EFI CRANK SENS SHIELD 22 J2B B14 Crank Sensor FLOATING
    EFI CRANK SENS SIG 20 J1A A30 Crank Sensor WHITE
    EFI CRANK SENS REF GND 20 J1A A14 Crank Sensor BLACK
    EFI CRANK SENS 12V 20 J2B B20 Crank Sensor RED

    Cam sensor wiring is per this post, but the pics are all dead there now so I am re-uploading the relevant image here:



    Crank sensor wiring is per DIYAutotune

    Since I had already verified the wiring, my first diagnostic check was to look for a misfire.
    I did this by unplugging my master disco for the injectors, removing all 8 plugs and wires from the engine, installing plugs into each of the 8 plug wires (outside the engine) and then with only 1 coil plugged in at a time, I checked all 8 plugs to ensure that they had spark when I crank the engine.

    Cylinder 3 actually was dead, but it was a wiring issue on my part. I corrected it, and all 8 plugs do have a strong spark now.

    I have also checked compression for the engine, and all cylinders are within 6 PSI of each other. Highest was 132 psi, lowest was 126 psi, and 4 of the 8 cylinders were at 130 psi exactly. (engine is about 9.1:1 compression, and I live at 6000 ft, so 130 PSI is pretty normal around here)

    Additionally, I attempted to run the engine without using the cam sensor, in both "paired" batch fire, and "bank to bank" batch fire. Neither batch fire mode improved the situation in the slightest.

    What I haven't done is checked the injectors with a noid light. I also never touched them, and it was running fine on sequential injection before with the TFI, so I have no reason to believe that there would be an issue now.

    I'm going to attach 3 system logs, as well as 3 datalogs, and the 3 Global Files that were used to make the 3 sets of datalogs.
    The logs are for running the engine on sequential fire/injection, as well as paired batch fire, and bank to bank batch fire.
    Datalogs.zip
    Global Files.zip

    As a quick reference though, these are my ignition settings for the sequential Global File:


    And here is an overview of the engine bay, so that you can see the arrangement of coils:


    Any thoughts on why I might be having the issue I am having? I'm looking forward to having the car back on the road for the late summer/fall driving season.

  2. #2
    Join Date
    Aug 2019
    Location
    Southern Utah
    Posts
    3

    Default

    I've made some progress. Adding some additional 12 AWG high strand count ground wires between my coil brackets and the cylinder heads has eliminated the backfiring, though I still had bad knocking. (This is temp wiring as a test, I'll come up with something less ugly later.)


    I then increased the Dwell on the coils to a flat 4.5 msec, and the knock seems to be greatly reduced as well.

    The awful eye burning fumes remain, and I appear to have uncovered a nasty misfire as well, as can be heard in this video:

  3. #3
    Join Date
    Aug 2019
    Location
    Southern Utah
    Posts
    3

    Default

    Sorry for three posts in a row, but I think I mostly have this figured out. Part of the solution can even be seen in the photo I attached in my last post; After adding the ground wires (which was done with everything disconnected for safety), I forgot to reconnect my coil pack sub-harness on the driver side.

    In addition, I found that at some point in my three days of trying to figure this out, cylinders 7 & 8 got swapped in the firing order within the Dominator ECU (be nice if there was a feature to lock that, or otherwise hide the re-sortability within a dialog box).

    The car runs OK now, though I still seem to have a misfire. I suspect the misfire may be due to the plugs, so I'm going to replace them with fresh new ones first thing tomorrow morning when it's nice & cool (the ones in there have over 23K miles afterall, and I've not been kind to them these last few days). Either way, I think I'm down to fine-tuning now.

    For the record, I have the TDC Tooth set to 6, and the Timing Offset set to -10°, thus synchronizing a commanded 20° of timing to an actual timing value of 20°.
    In the future, I'd like to design my crank bracket to be easily and directly adjustable, but that's an issue for later).

  4. #4

    Default

    Seems like you did a very thorough job of answering all of your own questions, but I just wanted to add that I've heard horror storied about the eBay/Amazon coils. I'd get a set from the junkyard, they are usually $50-$100 for a set of eight. Actually, that's what I did.

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