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With all of those tasks having finally been completed and with the car fully wired up again I cranked it for the first time in two months and it came alive on the first try!
(I did have to have a battery shop trickle charge the battery for a few days first).
—The three auxiliary electric fans and the revised power and control circuits for them worked perfectly.
—The revised HID and aftermarket fog light circuits worked perfectly
—The new fused setup for the TT fuel pump circuit worked perfectly
—The DC Power alternator seemed to work fine... but my voltage was STILL not rock solid stable. Accessory drive pulley squeaking from somewhere was audible and unless I pressed the gas pedal slightly to raise the revs the voltmeter was random and unpredictable between 13-13.1-13.5-14 volts depending on the revs and load applied.
Activating the A/C and heating system triggered the fan relay controller to activate all three auxiliary fans as it should and then the engine idle felt a bit better while the volts were much more stable at about 14V... mostly. Turning off the A/C reverted to the previous erratic voltmeter readings.
Even the interior overhead lights were not totally consistently lit, displaying slight flicker variations.
The engine idle and note was not perfect unless I raised the revs with the accelerator to 1,050-1,100 RPMs.
Eventually there was a hint of possible stumbling in the engine firing and.... the engine shut down.
I turned the ignition to ON and checked the OBD1 system for codes.
Sure enough.... another CEL 14 error.
I did not bother to restart the car again. It was getting late by then and who knows if yet ANOTHER $200 brand new igniter had just been burned. Checking its surface temperature with a laser heat measuring gun yielded barely 68 degrees and it was 55F outside at that time.
...
I pulled the ECU which is my third one. I know it had not been serviced for capacitors yet so I will inspect it and either do the cap service myself (I have brand new correct types already— ordered from Digi-Key months ago) or I will send this one to Tanin Auto Electronix just like the last one.
Additionally I will check the last previous ECU I used for any damage to the ignition MOSFETs even though Tanin did service that ECU.
I’ll do the same check to my very first ECU that I pulled suspecting damage from a bad alternator even though that one had been capacitor serviced by Aaron at Driftmotion a few years back before I ever got my engine swap running.
...
Beyond ruling out any issues with this ECU #3 or with ECU #2 or ECU #1 I cannot think of anything else to do other than open my wallet and buy an entirely new custom made engine harness from Tweak’d Tuning, Panic-Wire or Wiring Specialties.
Having gone through so much of my harness already I really don’t think I need a different/new engine harness to solve this issue but if none of my ECUs are malfunctioning or damaged at this point that is the only other thing in the system to replace.
...
For now I am also going to investigate the entire 1992-1994 SC hazard and turn signal wiring circuit and wiring path.
Any time the turn signals or hazards are used the voltmeter readings dip and spike very excessively. And to a small extent I think this may have been happening to a much, much smaller degree when I was using the SC300 in Los Angeles before I swapped to the new 2JZGTE engine.... though it NEVER once made the car unreliable and unable to maintain a consistent IGF signal between the igniter and ECU.
But at this point it’s one rock left unturned so I will investigate it just to perform the due diligence.
...
I’d hoped these two problems would be solved after all of this work but neither have been. And on top of it all this has preoccupied any time I would have given to initiating a full replacement of the 160k mile used turbos (the #2 of which is bad) with the new rebuilt stock CT12B's and associated parts that I've had on standby since August of last year.
Yet I now have a much better alternator (I think?), a MUCH better cooling system and much cleaner and more professional style add-on accessory wiring circuits with high quality Delphi connectors and OEM-level distribution boxes for the extra fuses and relays. So those are good things.
Hopefully I don’t get flat spotted tires with it sitting this long in the same position. It *was* to have been driven last night at long last but the SC had other ideas.
I just don't know what it is with this car and CEL 14 / igniter and unstable voltage issues. Everything I have done to address these things so far hasn't seemed to make a difference.
Sheesh Craig - what a nightmare to deal with. You've done so much nice work lately! Did Tannin service your GTE ecu? I've got my Aristo ECU and wouldn't mind sending it off to be looked at in case I try to go single and stay stock ECU this year...
As for the harness - hard to say... I'm tempted to say that a nice/clean/fresh harness with no corrosion and no old wires to split could potentially alleviate a lot of headaches. But - I know what they cost and they are a pretty penny!
Have you checked the coil pack clips, and the actual coilpacks for cracks? just having the locking tab cracked on a single coil can do that.
Also, I would highly recommend ditching the HID's, they play havoc on toyota wiring systems, even with relays and such.
throw in some LEDs, the newer ones put out as much light as a HID, without flickering or amplifiers involved, and come on 100% of the time.
On one of my SC's and my GX I would always pop one hid ballast sooner or later on a specific side, they are not toyota friendly even with a relay.
Not saying it is the cause but I tossed out all of my HIDs a few years back, the LEDs are all around better and no crazy voltages involved.
edit* just re-read some of what you wrote before and looks like you put in new coilpacks already. I would check the clips though that is a known problem if they were reused.
Make sure none of them are missing the plastic piece that goes inside to lock the pins also, for some reason they hold the pins in place better and may be more insulating material between the power and ground signal pins.
I would also recommend making sure every pin on the ignitor plug is seated and the plug is in good shape also, and locking tab in place which does help the pins stay just right as mentioned above.
I saw above where you mentioned you were thinking about changing the A and B plugs, I think that is a good idea at this point.
It sounds more like a wiring issue somewhere or a bad connection somewhere vs bad components like ecu or igintor to me.
The IGF signal is generated off of the actual ignition event, so with the misfire and then code 14 I think you need to focus on what can cause the misfire in the first place.
Along that line of reasoning, make sure the cylinder head is properly grounded, run an extra wire from the head near the coils to the the chassis or battery negative just to eliminate it.
That rear ground point tends to get brittle and not work so well, the intake manifold is also usually grounded but has gaskets inbetween and might not cut it all the time, same with valvecovers.
If none of that solves it, I would unwrap and inspect all the wires going from the ignitor to the coils. those get moved around alot and pinched over the years, only to cause problems down the line randomly.
Trying to think of everything I can cause we all want to see you get this back on the road doing burnout videos in mexico
I had a good sleep on it. Still tired honestly, haha.
I am open to switching from HIDs to LED bulbs but I thought with our old halogen projector assemblies the HID bulbs tended to put put a better overall beam than an LED bulb will.
I’m aware of the initial high current draw of each of the HID ballasts at near 18A that quickly goes down to 5A-4.5A as they heat up.
I am using a XenonDepot Phillips bulb kit. They’ve never failed me and don’t seem to be related to my issue when I’ve had a CEL 14 in the daytime.
Nonetheless I’m open to a good LED option if it’s just better technology now. Are there any brands or kits for our SC’s that you would recommend?
....
All of the other suggestions including as a last resort a brand new engine wiring harness I am open to.
I will get into inspection of the ECU #3 soon (and thank you for your kind offer Rudy!!) and see if there is any capacitor failure or damage.
But first.... I want to ask a small favor. Just humor me please. Rudy, since you have an SC with a 2JZ-GTE swap can you take a clear picture of the back of the intake manifold where the ground to the chassis is located and post it here? And please take a picture of where that ground wire leads to?
I’ve been looking at all the factory ground TSRM diagrams for the SC300, 1995 Supra TT and 1997 Supra TT as compared to my car’s setup and installation and I want another example from someone else’s swapped SC Just to be sure everything is as it should be.
I’d appreciate it a lot and certainly no rush. Just whenever it might be convenient.
If craig posts a burnout video then I think we have a CL burnout challenge on our hands. Count me in!!!
I'll have to find another SC first lol. With all the troubleshooting already done and needed I would also be tempted to throw a new harness at the problem too but installing one in the car is a bit of work also.
I don't think they are related either but figured I'd mention them since you were talking about voltage fluctuations etc.. would be worse at night with them on I bet.
If anything I think my LEDs put out more consistent light than the HIDs. On my GX my cutoff lines are super clear and they were originally projectors for halogen lights like the SC.
I got the one that has the heatsink looking thing on the back of it, just make sure you have clearance to like the battery etc..
The best part is they are just plug and play, and tax the electrical system less than the original setup, not more like HIDs do.
You couldn't pay me to install HIDs after using LEDs, have had them on 3 vehicles not a single one has failed and always come on with the auto on.
Would you guys believe I have never actually done one of those yet? Legitimately from a dead stop that is. My cars were always too underpowered or FWD or underpowered RWD with too much grip for that.
Breaking tires loose while turning for fun yes. But still not even a first burnout yet.
I am hoping I can do such silliness in this thing for the first time once it’s fixed
I'll have to find another SC first lol. With all the troubleshooting already done and needed I would also be tempted to throw a new harness at the problem too but installing one in the car is a bit of work also.
We’re all waiting for you to find another SC that you're happy with, Ali
I wouldn’t want to remove a harness with the engine in the car. Not a stock one at least. It seems like so much to dismantle mechanically to get it off.
In my case if I ever had to do that, since I also still have to replace my turbos with the new ones, it would make more sense to pull the engine with transmission attached, stabilize it on a couple of tires and keep the engine crane attached for stability. Then both jobs could be addressed much more easily.
Of course... having a garage is prerequisite for that.
Just a matter of time before I get the right one, been busy lately so waiting till I have some time again.
You are right when it is time to pull it for the turbo's that would be the time to do it. hopefully you can sort it out by then but having a fresh harness isn't the worst thing either
Grounding review (to make sure I didn’t miss anything obvious)
Here are the ground point diagrams from the 1992-1994 SC300 electrical TSRM and the 1995 and 1997 Supra MKIV TT electrical TSRMs.
1992-1994 SC300 2JZ-GE:
1995 Supra 2JZ-GTE:
1997 Supra 2JZ-GTE (as far as I can tell all the ground points are identical to the OBD1/1995 diagram above):
In reviewing them all and some threads on SupraForums I note that there are several major 2JZ-GTE engine and chassis grounding points:
1) Engine block to battery negative
2) Engine harness to chassis passenger side (LHD orientation)
3) Engine harness to front and rear of intake manifold
4) Starter unit ground wire to chassis (or battery negative?)
5) Transmission casing to chassis 6) Intake manifold rear to chassis on driver’s side (LHD orientation)
7) Cylinder head at engine hook bolt to top of firewall right next to the engine harness plastic protector casing
Please someone correct me if I am wrong about any of these.
Okay, so with all of that noted here’s what I am noticing with my car:
—Yes, I previously tested all the ground points I could find and which were strongly suggested that I look at on the engine assembly itself.
—However I think despite all my meticulousness I may have possibly missed something crucial but extremely obvious to.... well... every SC, Supra and JZ vehicle owner but me apparently (if I am correct):
What I am concerned about here is that while the engine block is well grounded, starter is grounded, transmission casing is grounded, intake manifold front and rear from the engine harness are grounded and passenger side harness to chassis ground are all present....
...but I have no individual ground straps that are not directly a part of the engine harness which connect the following:
—cylinder head rear (at bolt from engine hook) to the chassis firewall Metal
—intake manifold rear ground to chassis metal just behind the shock tower.
.....
Now... this could just be another red herring at this point because I’m trying to think of anything at all that I could have missed when I first installed the GTE engine due to my ignorance.
However when studying the electrical TSRM ground points for the 2JZ-GTE and 2JZ-GE it concerns me that perhaps... perhaps... without any external ground straps coming off the cylinder head to chassis there may be an excess bottleneck of electrical resistance to any part of the system that grounds to the cylinder head and/or intake manifold... since a head gasket separates the iron block and aluminum head.
I *think* the intake manifold rear ground connection from the harness is where the igniter unit grounds to and where the ECU ground leads to (unless I am mistaken— I will have to review the electrical diagrams again to be sure).
If I have this right then it is *possible* that an electrical bottleneck could be affecting the igniter unit, ECU, ignition coils by extension and who knows what else.
At this point I don’t think I have much to lose by adding two custom made 6-8ga ground strap wires to these locations.
Again, maybe I am just exhausting myself with another red herring theory but it sure sounds like there should be two totally separate ground straps in these two locations per the factory manual which I do not have installed in my swapped SC.
Further, if I am right and this ends up being the true source of my CEL 14 issues then it concerns me that electronics damage beyond just igniter failures may have been happening ever since I got this swap running.
When I assembled and installed the new swap it only occurred to me to connect the wiring harness properly and ground the engine block, starter and transmission.
If, all along, I needed a separate cylinder head firewall ground and a separate rear intake manifold chassis ground which I clearly do not have... then this may explain a lot.
Again... if I am correct in all of this then it was not obvious to me but that would have been pure ignorance on my part.
Fingers crossed that this isn’t another red herring theory. Because weirdly the SC with this swap has seemed to run just fine for many months at a time.... until I had yet another igniter and ECU issue come up.
...
Edit: I found an example of a 100% stock Supra MKIV TT engine bay online and it does have a visible ground wire at the rear firewall's top right near the engine harness plastic cladding that seems to lead to the side of the cylinder head at one of the engine hook bolts (circled in red).
It's harder to tell if there is any direct to chassis ground wire coming off the rear side of the two intake manifold grounds (also circled in red with an arrow pointing to the chassis at the foot of the shock tower).
So I must add a ground at those two points at the cylinder head engine hook bolt and upper firewall before proceeding with anything else.
Supra MKIV Turbo stock engine bay example picture:
Hey Craig - just now saw your request! Looks like you were able to find that location and I can double check my car tonight to verify (drove my Taco to work today instead). Insufficient ground could certainly cause an issue but I just don't feel totally certain that could be your issue...
As for that burnout - I have no problem helping Ali scumbag you into your first! haha! Something about a good sitter is just really liberating!
That is the main rear ground point for the cylinder head I was referring to, it tends to get brittle and damaged over time as the ends are exposed and not shrinkwrapped etc.. it is also easy to leave off since it isn't part of the main harness.
On the GE engine it goes to a bolt on the rear passenger side of the head. On the GTE though I can't remember, but there should be an obvious looking spot on the head for it.
I honestly think that is the issue, power actually flows from ground to positive so it is as important to have an ample ground especially to power the coils.
if you throw a meter on the cylinder head it will still read like it is grounded cause of the smaller grounds all around, but I don't think those can handle the load of the 6 coils by themselves as they are also providing ground for sensors etc..
Haha, Rudy I have been looking forward to a real burnout, believe me! The stock twins must be replaced before that can happen though
No worries about confirming that ground. If you happen to have time to snap a picture of it I’d be most appreciative!
Ali— what you say makes total sense and I am now kicking myself that I didn’t think about just adding a ground when I had the new engine on a stand four years ago.
Had I done that before ever getting the engine off the stand I might have avoided the majority of these troubles.
If adding this ground cures the issue that is.
...
It is a tight fit to get to that 14mm rear cylinder head hook bolt and the quality of my Duralast and Pittsburgh open end wrenches leave something to be desired compared to a Mac Tools or Snap-On. I don’t want to risk stripping that bolt out while attempting to temporarily remove it.
It would be easier to get to if I were to remove the 2JZ-GTE’s IAC-V assembly... which involves a new gasket and draining the engine coolant.
Instead, what do you think of using this very accessible bare cylinder head bolt hole in the middle of the head casting just behind the throttle body bracket?
I have a spare 91651-A0814 OEM Toyota bolt that fits there perfectly and a spare 90119-06512 OEM bolt fits at the open bare metal bracket spot mounted to the firewall for the other end of the connection.
Since Toyota’s factory specification point for this head ground connection is that bolt on the GTE rear engine hook, I am using an 8GA wire with 5/16ths ends just to ensure there are enough copper strands to handle the current flow.
What do you think? I’m installing it tonight but is this still not a good enough solution?
2023 Edit: Two years after doing this temporary solution it still turned out to not be enough. I removed this irregular ground connection and re-fashioned the end with a standard 8GA 3/8" hole ring terminal and affixed it to the rear engine hook bolt as the Toyota diagrams instruct. Hoping that will be the end of it.
To get to that engine hook bolt with the engine assembled and installed the coolant must be drained, EGR VSV and EGR Vacuum modulator disconnected to make room, then the Idle Speed IACV has to be unbolted, disconnected from the small fat rubber hose, that fat IACV rubber hose has to be removed temporarily and the metal rear coolant pipe that it connected to had to be slightly pushed out of the way. Then the #6 injector connector and rear camshaft sensor connector both have to be temporarily unclipped and pushed out of the way. A 14mm long closed end wrench (do NOT use the open end of the wrench) can loosen the rear engine hook bolt to remove it. Slide the 8GA 3/8" ring terminal over the bolt and reinstall in reverse order.
The rear engine hook takes 29 ft-lbs but it's hard to get a torque wrench or torque adapter in there so tight. The fuel rail prevents pretty much any 14mm short socket and 3/8" torque wrench from clearing so tightening up with a guesstimate of what 29ft-lbs might feel like is the best one can do. The Isle Speed IACV goes back on with 15 ft-lbs each using a 3/8" flex adapter and one brand new metal gasket P/N 22278-46010.
And then, just now I added this additional 8GA wire from the ground at the rear of the intake manifold to this spot on the chassis behind the shock tower.
Will that be of any help or should I remove this additional wire?
For the first wire I think that should be fine temporarily, I would make sure that the part on the cylinder head underneath the bolt is very clean so it makes good contact.
I don't think adding the second wire will hurt anything either, until you get it working the extra ground shouldn't hurt. hopefully that helps out some.
01-20-21, 12:17 AM
