MartinS

Sorry Adam, got things back together but I've screwed something up and have to troubleshoot. Might be able to get it done on Wednesday, if not it'll be on the weekend.

Will do. Will take a day or two to get things back together.

Thank you Adam, I very much appreciate the effort you're putting into this. No worries on the timing, I've got plenty to do getting the wiring harness back on the engine and no real time to do much until the weekend coming up.

Spent weekend removing engine harness, removing all coverings, cleaning and inspecting all individual wires, and re-covering/insulating. Found a couple of very small nicks in wires and repaired, didn't appear significant though. Will re-install and test but strikes me unlikely to have helped. https://drive.google.com/file/d/1UksUG7AmuBffU3bGLmgIVhApd24oDBNo/view?usp=sharing

Hi Adam, Well, it's been mid Nov since I was able to do anything with this. In that time, the ECU has been shipped to Detroit and tested by your tech team and found to be functioning without fault as you thought. I have spent a bit of time researching possible solutions and changed my engine and all engine/ECU ancillary equipment to a star grounding system with all grounding through one point on the engine block and back to the battery via welding cable. Re-installed ECU today and tested: no change in engine behaviour. Misfire and trigger error counts starting at around 3000RPM. Not sure what next. I did have the engine wiring loom off the engine when I was prepping the engine for install at which time I cleaned and inspected the loom, replaced some plugs, and tidied up with loom tape for re-install. Do I need to go through it again? The only sensors I either haven't replaced or run without are the LH intake cam position sensor and the MAP sensors. Should I get a new cam sensor? New MAP sensor? Is there a next step I am not seeing? Cheers, Martin

Ok, thanks, will do Adam.

House batteries have a shunt and are chassis grounded with solar and DC-DC charger. Batteries in and out of circuit, no change tracing. All tracings have been with house batteries off. Have not tried disconnecting DC-DC charger but is connected directly from batteries to +ve post battery, seems unlikely to be an issue. Small 600W inverter has been off entire time. Only commonality is same attachment point for ground as strap from transmission. 110V mains only supply socket in living area, used for battery charger for engine battery. Plugged in or not makes no difference. Power supplies for the engine through a series of 5 relays controlled by ignition switch, each one separately: ignition, ecu, fuel pump, e-throttle, and voltage feedback to alternator. Can't remember which one also has Wideband controller. Not a complex supply, can take pic of circuit diagram if helpful. Starter has a lockout relay which is controlled by a security device. Circuit only connected to starter solenoid. No other circuits associated with engine/ecu. Bought and installed new socket to plug into crank trigger. Wired direct from crank trigger to Link wiring loom with new shielded cabe. Should I run this from trigger sensor directly to the ECU bypassing the Link loom? Looking more closely at the tracings, whether cranking or running, the voltage is shifted from the zero point to the +ve side by a factor of 1.5 (always 1.5 times more positive than negative).

Since cam position sensors are 12V and grounded to the sensor ground, I wondered if, like some other 12V supplied sensors, this was incorrect and they should be chassis grounded. Although signal leads disconnected, signal grounds to ECU and 12V power to sensors still connected. Disconnected the three currently unused sensors and grounded LH intake cam sensor to chassis. Setup as above, alternator not in circuit. No change in tracing. Tested revs by manually opening throttle, hits 'rev limiter' effect around 1500-2000 rpm, much misfiring. I'm actually pretty depressed about this Adam. The finish line, which I thought was in sight in May-June (admittedly delayed by harness and transmission issues as well...those have been solved for some time now), seems to get further away the harder I try to solve this. Maybe I'm missing something but is there any chance this is going to work out?

Alternator out of circuit completely. https://drive.google.com/file/d/1rHymzgCrjrg7i8tKrQjzYz90Sl31uq1j/view?usp=sharing

Ok, easy to do

Will a new ECU fix this or is a Link ECU not able to run this setup? Seems like it should be able to but...I've spent so much time on this one problem and have a significant financial investment in the vehicle. I really just want to get the engine running and be able to use the vehicle which I thought was going to happen weeks/months ago. I feel like I need to cut my losses. With no solution in sight, what's my next best move? I've spent in the neighbourhood of 20-30 hours on this problem in the last month. Should I replace all my ignition modules? All my injectors? Have another (3rd) new $180 crank trigger. New cam position sensor(s)? Not much else to replace as it's still not a good tracing with nothing else plugged in. Can't test it at 2000 RPM to see if it still misfires and dies at 2500 RPM because all the e-throttle is disconnected. I can get another engine for much less than replacing all the electrical items on the engine. Is that the solution?

I'm out of ideas

https://drive.google.com/file/d/1nE1j7uwC-OKVzQoqtAJkFGg2ZJyfjYzL/view?usp=sharing Extra ground strap added to engine. Checked for ground loops in sensor ground. Ign 1-6, Inj 1-6, MAP, +5V, grounds and +12V only connected. Won't run without MAP.

The car will run on only 2 cylinders. Can you tell me the absolute bare minimum I need plugged into the ECU to have it run? If it still has an abnormal tracing while running...I don't know. But if it's then normal, I think it would be better for me to do what you originally suggested and start plugging things back in. I'm getting to the point where I'm thinking unplugging more things will prevent it running and I can't tell if the tracing is good or bad because it'll be good cranking only. For example, when I disconnected the MAP pin, it would fire but not sustain run. Enough to see tracing was abnormal though.

These 2 tracings demonstrate what I mean about cranking vs running. In these, the first pic shows the engine cranking. Ign and Inj 1-4 are unplugged. Inj 7 and 8 are unplugged as you suggested, Ign and Inj 5 and 6 are plugged in still. First pic shows the cranking and I got excited as I think it looks really good. Then the engine fired and ran (on cylinders 5 and 6 only...and really ran surprisingly smoothly!) and the tracing in pic 2 shows the trigger tracing running and it's back to looking bad. https://drive.google.com/file/d/1RdpsYcZeByufbi4t9bUkrCrPrRP0yD0u/view?usp=sharing https://drive.google.com/file/d/175_GAYqRoAU2sck4iaLQuuybp8eW2bHf/view?usp=sharing Anything that can be inferred from this?

Remove 7 and 8; no change. Have started to progressively remove 'blocks' of leads (mostly from plug A so far). Here is a pic with a list of what's removed. The engine runs surprisingly well on 2 cylinders(!) and I did all this running on cyl 5 and 6. I then removed 5 and 6 and ran on 3 and 4 just to make sure nothing changed. So far a pattern has emerged which is shown in the linked pic where the engine starts about 1/3 way through the screen. https://drive.google.com/file/d/1KNn0ucexch4_2S_TdGphNE3hhs3E6NwG/view?usp=sharing With cranking, I have a pretty good tracing. As soon as it starts, it looks like above pretty consistently. I have pics at pretty much every step listed on the paper in the photo. I'm going to go through in more detail but I didn't really notice any changes when doing it. Does normal tracing when cranking now and abnormal when running help in any way? I can't think of the implications....

Ok, will do Yes, I see what you mean, definitely changes when engine starts...

Been looking closely, the tracing seems to be symmetrical at the toothless zones even though it wasn't with the previous tracing with thee same pins connected/disconnected but it's definitely shifted significantly positive. I interpret that to mean I need to keep looking...

Hi Adam, got down to looking for fault today. What I had done is remove the 2 ground, 2 sensor ground, 2 triggers, +12V and +5V sockets from plug A and put them directly on their pins. I also plugged B back in and with this, the crank trigger tracing was normal. Today, I put all the above sockets back into plug A, plugged A into ECU, normal tracing. Then removed A, plugged B into ECU, normal tracing. Next plugged both A and B back into the ECU. So everything plugged in. Cranked, engine ran, abnormal tracing. https://drive.google.com/file/d/1GUZi4WEoJzeOEZMGQNnWDoTOn2knTpj3/view?usp=sharing Began removing sockets. First, Inj 1-4 from plug A. Abnormal tracing. https://drive.google.com/file/d/1B1lLNabDivWjAYWgoe8KxIwjmU-U518L/view?usp=sharing Next, Inj 5-8 from pin (Inj 1-8 now removed, everything else connected) NORMAL TRACING! Pretty sure anyway: https://drive.google.com/file/d/1KVDCj2OB8RNZN4Z-r7XnIrKW0_YIlB_9/view?usp=sharing So, I stepwise replaced 8, 7, 6, then 5. So back to same setup as only Inj 1-4 removed from A as above. Now the tracing looks normal to me (engine starts half way through screen): https://drive.google.com/file/d/1CQef2K9CvIt73uVD6jPah3eL9Ir4EUrB/view?usp=sharing Am I misinterpreting this? I hope so because I don't see how it's possible: remove 1-4 and the tracing's abnormal, removing 5-8, normal, then replacing them and the tracing's normal in the same config it was just abnormal in? I'm lost... Ok, now I look at it more closely, with Inj 1-8, while the toothless trace is now symmetrical, the overall tracing appears to be shifted to +ve voltage. If so, the morphology has normalized but the voltage has shifted. I can't interpret that. Sorry, with Inj 1-8 removed

Yes, all the sensors plugged in, only not plugged in at the ECU. If you don't have a suspected order of candidates, I'll maybe just go row by row, seems as good a plan as any. I'll let you know how it goes...

Hi Adam, just got back to work on things today, I've now stepwise plugged in a few more things into plug A. Attached is a scope with all of plug B, plug A +12, both ECU gnds, both triggers, both signal grounds, and +5V. As well, everything with +12V power powered up. https://drive.google.com/file/d/1qytcVx6x3zuoeuWj_-jLldEtc9mZ_A4c/view?usp=sharing Still looks ok. So is something leaking voltage into one of the inputs or outputs? Is either more likely? Given your knowledge of the architecture and these problems, are any candidates more likely to be a problem (ie ignition outputs likely, injection unlikely)? Or are any of the remaining leads equally likely. Just trying to get a systematic approach to next steps and do a little less cranking....

Ok, I see what you mean now. I was never really sure I understood what you were seeing. I was looking more at amplitude not symmetry around the zero V point. Looks much more obvious to me now. I already ran a scope with B loom plugged back in. Here's the link. https://drive.google.com/file/d/1Iu_FizZq7sCGTXvrg4SfjBh46LLGNnKn/view?usp=sharing I think it looks ok which leaves me with the grounds on A loom. Do you agree?

Trigger oscilloscope screen, cranking with plug A trigger1, trigger-ve, 12v, and ecu ground only attached, plug B unplugged. https://drive.google.com/file/d/19JVboSeOYaNUWV11ACwa5hPYOfZdm2U7/view?usp=sharing, https://drive.google.com/file/d/1pkz7g8J9eEn-iBSVnwiwz4k5NsfI4nUP/view?usp=sharing Sorry, pics not centred well Different part of cycle. https://drive.google.com/file/d/1RA2_nGb2opIreS1V91bdVEgmwogJ79eS/view?usp=sharing

Not sure how to interpret these results. They are reproducible and consistent. Seem to imply there is very little to no leakage into the ground but there is some at 18 mV. The source could be any of the sensors grounded through the ECU which have a voltage supply I suppose. These are the cam position sensors, MAP sensor, Wideband O2, and foot pedal and throttle position sensors for the e-throttle. Only other source the ECU. Nothing else signal grounded which has power supply I can think of. Is it worth disconnecting these to see if one of them is causing the small voltage in the ground? The small voltage leak (32 mV) in the crank sensor signal line is from the ECU as there are no other connections in the wiring loom. Is this normal? Are either of these voltages or the differential of 14 mV between signal and ground enough to cause the interference with the crank angle sensor signal seen in the oscilloscope tracings? Do either imply an internal fault in the ECU? Not sure how to proceed from here...

At the plug to the sensor, Ign on, 32 mV on the signal socket, 18 mV on the ground socket