KahnBB6

iTrader: (5)

Nick,

The shop is Monsta Performance Inc. They seem to have very good reviews online and have experience with Haltech ECUs (when I visited there was a 2JZ-GTE VVT-i swapped GS300 there out front running a Haltech just getting the tuning kinks ironed out between the car's owner and a technician). They aren't sitting around on always unfinished customer cars. They appear to me to be regularly moving through customer vehicles, of which there are a variety of usual JDM suspects: Supra MKIVs, R35 GTR's, R32 and R33 Skyline GT-R's (and maybe a GT-T?), at least one Silvia, a GTE swapped GS300 or two, 350/370Z's and some others that I am forgetting right now.

I didn't see any SC's or Soarers there but when I spoke with the service and scheduling liaison Alexis she said they have seen a few come through. She said they had been around and operating as a business for maybe 5-6 years now. I met the owner briefly-- nice fellow as well. I just went in to get an initial sense of their shop and its vibe and kept our conversation light but everyone was busy with the work and problem solving... all things I appreciate in a good specialty performance shop.

They might also be a good place for you to check out and consider to help with for own long term project goals for your SC400

CLass of 1

I will keep them in mind! Sounds like a decent outfit. Thanks!

Nick

KahnBB6

iTrader: (5)

Welcome, Nick!

It won't be for a bit but I'll update you again with my further impressions whenever I am back in contact with them regarding getting work done to my SC.

KahnBB6

iTrader: (5)

Interesting development over the last few days after doing some further testing.

I have noticed that with all the fixes to date, with the new OEM Igniter and with my #4 stock ECU (no capacitor replacement service yet) that the car does just start right up into closed loop mode, come to temperature and idle. Once time it died on its own after idling for a very long time (20-25min?) but apart from that I always just shut off the car myself as normal.

On one of these nights after letting the oil pressure get up to temperature I took it around and up and down my driveway to cycle the brake rotors a bit. No issues then.

So a couple of days after that one afternoon I decided I should take the SC out for a quick errand and back. It would have been the first drive with it in two months.

I got it warmed up and got to the end of my driveway when.... it died. I was able to start it right up though and throw it into reverse to back it into its spot with some engine power... before it died again and only left me with momentum and my brakes to do it with. I did check to see what CEL this gives me and it was Code 14 again... but as you all know well all you need to do with these cars with a manual transmission is to stall out the car and you can pull the same code right after.

Okay.... I was in a rush that afternoon so I took the other car.

(Note: I often put a battery tender on the car after most of these tests just to keep it topped off since there has been no significant charging while driving for a while).

....

Tonight, forty eight hours later, I experimentally turned the SC over again. Once again it started RIGHT up into closed loop until it got up to temperature and then settled down. Once again I revved several times to see if it would die because of that. Nope.

So then I disconnected the battery and swapped out stock ECU #4 and swapped in stock ECU #2 (which was capacitor serviced by Tanin Auto some time back).

I tried starting with that one and yet again the SC came right to life and settled into a nice idle. More experimental revs and still I couldn't upset it and force a shutdown.

I put the A/C on at full blast and turned the radio on. I was hoping the cooling fans would also kick on but it's cool out tonight so no dice. More experimental revs. Still rock solid.

YET... not too long after that the car unceremoniously and quietly shut down. I hardly noticed at first with the A/C fan and radio both still being on (my car has stock exhaust mufflers fitted).

......

So NOW the plot has thickened. This has never happened before. A shutdown of this nature has historically meant I have a failed or mostly failed igniter. That cannot be the case this time (?) because every time I am able to restart the car without issue.

Maybe I did solve the old problem after all... and at long last... because this issue isn't related to a specific computer having gone bad and the igniter seems to otherwise be very happy doing its thing.

I am beginning to wonder if there is some circuit or component which may be bad/old/worn and only affects the engine to cause shutdown when that component itself is worn. Just my hypothesis.

Or maybe it's related to the old and used USDM 2JZ-GTE Fuel Pressure Regulator? Its FPR VSV is new but the OEM FPR is old. I have a new OEM FPR in my spare parts if I need it.

...

Or maybe this is all still related to either the main ECU or Supra TT Fuel ECU... but I am getting the same behaviors with different spare identical main engine ECUs and with both of the Supra TT Fuel ECUs that I have.

If I try to drive the car it will definitely shut down sooner than this (I think) but I never drive until the engine is warmed up so I couldn't say.

Every time this happens I can just start right up again into normal idle.... until the engine eventually shuts down again on its own when it's well into full operating temperature at idle.

I'll have to consult the TSRM troubleshooting matrix but that hunch I have still leans on some component misbehaving once it is sufficiently warm. I could be wrong though.

LeX2K

At some point after swapping in multiple components and having essentially the same failure you need to conclude the problem is elsewhere. My hunch is some copper corrosion (green crustys) where there is a connector or possibly inside a fuse box.

Of course I could be way off but I think you've all but eliminated component failure. Not sure on the fuel pressure regulator.

KahnBB6

iTrader: (5)

I think you're right on this. I have a couple of minor lingering things I can replace (could install a new OEM FPR, new OEM SC300/400 fuel filter at the rear, could find and install a new OEM IACV if they are still available) but I am also with you in suspecting some sort of copper corrosion *somewhere* in the car or perhaps even a bad soldering joint in my engine harness.... but... it would have to be in some area where something makes copper contact with something else, right?

Still possible that a test with a standalone ECU might yield a eureka and implicate one of my stock ECUs... but ALL of my stock ECUs? Unless something has damaged them all in the same way I'm not so sure now.

....

I did replace the AM100 and 120A ALT fusible links with brand new OEM examples after I saw corrosion on their inside slow-blow metal area.

The alternator is charging the battery normally and thus my battery isn't being drained while the engine is on. No "Check Battery" idiot light comes on.

...

I'm too tired to think on it further tonight. Tomorrow.

On a side note I lucked out buying a reasonably priced good working used 40k mile set of USDM 2JZ-GTE CT12B turbo actuators. When I asked I was informed that the #1 wastegate in that set has never had to be fitted with a spring mod to help it out which is a good indication of its overall health They won't be useful immediately (the turbos need to come out of the car in order to fit them) but perhaps later they will be. That and my spare set of CT12B's don't have good working actuators so these will replace those old and faulty ones to create a good healthy set of spare turbos.

estSC

A bad connection in the engine harness or ecu power/gnd seems likely. Before I got a standalone ECU I had a similar problem. the car would cut out while driving and most of the times would not start back up. After a few minutes I try again and it started right up. Turned out to be a bad connection to the ECU ground.

RudysSC

Man, Craig, WTF LOL. I'm with these guys - I can't help but think you've got a bad connection somewhere and also refuse to believe all of those ECU's and igniters can be bad... A fuel filter mightttt make sense, however, with how intermittent it is my gut tells me loose connection somewhere. If you can re-create and manage to pull another code perhaps it can at least lead you to the right circuit rather than having to go through your engine harness and connectors pin by pin... But the issue does not seem mechanical or single component related (unless your IACV is doing some seriously strange stuff when it gets hot).

Fingers crossed for you. You may need to get a second look at that thing. Sometimes all it takes is a fresh set of eyes on a problem. From time to time I have a friend come through when I'm struggling and they are often quick to suggest something that didn't even cross my mind amidst my frustration.

KahnBB6

iTrader: (5)

Yep. I think everyone here and I feel that has to be the issue. Gerrb also hypothesized this over the last few months when I talked to him about it. I don't know how... but that has to be what is going on here.

When you went with a standalone ECU was it only then that the poor ECU ground was identified and corrected? Or did the installation of the standalone ECU correct the problem with no additional wiring changes being required?

I would assume that once identified and zeroed in on one or more wires had to be corrected in your car.


​​​​​​​
Thank you Rudy! It's definitely a puzzle. I am not ruling out installing a new OEM FPR and fuel filter but I think those would be general maintenance things. the last time I vacuum tested (with my MityVac tool) the FPR going by the TSRM guidelines it performed within spec.

I agree that a second set of eyes will be needed soon to give me an informed opinion. Thankfully I do have just such a local specialist shop in mind who can probably help me.

I am also not ruling out getting a brand new engine harness made by Tweak'd Performance. Tonight I pulled my untouched original 1993 SC300 5-speed CA Emission engine harness from storage in preparation for that. I'm also going to go over my old conversion harness wiring notes to put down what additional wires I need run.

LeX2K

That's a super clean harness.

KahnBB6

iTrader: (5)

Thank you! I held onto it thinking it could possibly be useful someday if ever I needed to get a new swap harness built. I'm glad I kept it now. My car had only one owner before me and it wasn't modified before I bought it so the harness was never messed with.

Although the plastic cladding and layout are different between 2JZ-GE and 2JZ-GTE engines so I think at minimum that hard plastic from my 2JZ-GTE harness will need to be swapped over once it is converted. Possibly some rubber grommets and ribbed elbows as well.

estSC

I found the problem before going standalone. But my harness had several splices due to the engine swap. So a completely new harness was put in for the standalone because it was easier and for the peace of mind.

KahnBB6

iTrader: (5)

I agree with your solution and I think this is ultimately what I will do.

Just yesterday I came across a TSRM test of the ECU Ground pin's resistance through the ECU itself and through the chassis ground path that pin goes through. I will be checking on that in a day or two when it's warmer out.

I'm also going to replace the ground wire from the transmission casing to the chassis with a brand new 8GA.

Yet I think for me this all leads back to the issue you found in your own wiring harness-- likely a questionable splice or possibly compromised wire in there somewhere that has been causing a lot of this even while some of my other mistakes which I eventually corrected added to my car's odd symptoms.

KahnBB6

iTrader: (5)

A little update.

I still haven't been driving my SC. It's been easier for me to just leave it parked while I deal with other matters. But I do start it up every 3-4 days and top off its battery with a trickle charger. Each time it starts RIGHT up, does its high idle well in closed loop mode while still cold and reaches a normal idle once it reaches open loop mode. So far I have had no further issues with it dying all of a sudden... but I also haven't let it idle for 15-20min for a while either.

In addition to building a fresh transmission to chassis 8GA ground wire to replace the old one I have kept coming back to the fuel system... and my suspicion of my fuel pressure regulator possibly having developed an issue.

I suspect this because:

A.) I did install a USED OEM Toyota USDM 2JZ-GTE FPR which was said to have "50k miles" on it. It has worked perfectly fine when I first assembled the engine and I didn't think anything of it. One of the very few used consumable parts I installed during my engine build.

B.) I began researching what could cause a car to stall out in its fuel system and one glaring thing that kept coming up in many articles is low fuel pressure. Then I looked up what fuel system malfunction could cause a car to stall out while going up or down a hill.... and again one common culprit seems to be low fuel pressure. It is said that on level ground this problem will not manifest but will when the vehicle is pointed on an up-cline or down-cline.

C.) My SC seems to act totally normal unless I let it idle for a ridiculously long time... or unless I attempt to take it up to the top of my driveway (which is a small hill). That seems to make it stall out fairly quickly.

So... I think what I may be experiencing now is a possibly failing fuel pressure regulator that is not maintaining correct fuel pressure.

--My Denso TT fuel pump was brand new in 2018
--I have verified the same exact behavior with two different MKIV TT Fuel ECUs that I am pretty sure are in good condition and functioning normally. The car is wired to run in the stock 9V/12V mode with this beefier fuel ECU.
--My USDM 2JZ-GTE Fuel Pressure Regulator VSV was a brand new part installed in 2018 and its vacuum lines are all new
--Everything bolted to the fuel system at the engine was fitted with brand new OEM crush washer gaskets at the correct torque specs
--All six OEM 550cc low impedance injectors were sonic cleaned and balanced by Driftmotion prior to installing them into the engine in 2018
--I have before this tested my USDM GTE Resistor Pack and it did not have any issue out of normal spec
--I do not detect any misfires at the tailpipes when the engine is on. I verify this every time I run the engine

So this leaves me suspecting... since my ECU and electrical system issues have either been finally solved or seem to have taken a hiatus for now... that it is the used FPR which needs to be replaced.

Also... the fuel filter at the rear of the car hasn't been replaced since perhaps 2016 or so and it has also been suggested to me to get a new one in there anyway.

....

Toyota has discontinued the OEM USDM 2JZ-GTE FPR (P/N 23280-46030) but I do have a brand new one I bought a few years ago as a backup. So I will install that.

I also have a new OEM SC300/400 fuel filter on order (P/N 23300-50040) and will install that as well.

The USDM 2JZ-GTE's factory stock FPR takes two metal crush gaskets upon reinstallation (P/N 90430-10012).

Aftermarket OEM direct fit FPRs for the stock engine configuration are still available at this time... I think?

The coolant has to be drained and the throttle body has to come off in order to get to the FPR which means a new throttle body gasket is also needed upon reinstallation: P/N 22271-46030 for USDM 2JZ-GTE's.

....

So all of that and replacing that under-chassis trans case to body ground for good measure are my current to-do items.

That and maybe adding some Sta-Bil to the gas tank or siphoning out the gas and refilling it with fresh gas if this takes much longer. I haven't driven the car anywhere since mid-January (well... one drive only but while experiencing some issues) so the fuel is getting older... but it's not too old yet (93 octane 10% ethanol).

If after getting those things done I still have noted issues I'll then take it in to the local shop I found recently and see what they tell me.

The plan to get a new engine harness built by Tweak'd is still a long term to-do.

.....

And in OTHER news... I'll be adding a second car to my stable this year! After a LOT of research and weighing of variables and pros and cons I decided on a model and a couple of weeks ago found a dealer I felt comfortable working with (for an MSRP sale) and put a deposit down on their waitlist for a GR86 Premium 6-speed manual in one of four colors I'm flexible on

It'll be a few months of waiting but I am excited for it! And I already know all the changes I want to make to it (But they won’t be many— mostly Brembo brakes, slightly wider tires, a 4.30:1 final drive ratio and some other very minor odds and ends).

Although... the supply of them is so constrained it's a long waiting game. And for whatever reason Toyota's production agreement with Subaru has them making something like 80% of GR86's in automatics... while Subaru makes at least 80% of their BRZ version in manual. I truly do not understand Toyota's reasoning there (or their allocation only distribution system but I digress).

My SC isn't going anywhere of course. It is going to be shifted into being my secondary use classic vehicle within the year though. And in the long run this takes the load off of my shoulders stressing over it all the time. It will also make it easier to get its oil pan replaced (a full engine out job) and get its long term cosmetic restoration underway once it is no longer always being relied on as my primary vehicle.

....

Also since we all like pictures in threads I've got a fun one to share from a visit to my local Toyota dealer yesterday to pick up a parts order.

I just want to be clear that I am NOT in the market for one of these, lol... but I couldn't resist snapping a picture of the 2023 GR Corolla Morizo Edition they had sitting in their showroom. The dealership's owner got dibs on it for himself unsurprisingly but it was a very cool thing to see there! I highly doubt I'll see another Morizo given that there are only 200 of these things being released for the U.S. ;D

And to be clear I am NOT in the market for one of these! But how could I not want to spend a few minutes checking out such an amazing machine?

RudysSC

Ayyyyyy congrats on the new car Craig! I parked next to a new one the other day and loved the GR86 in the snazzy light blue. It looked great next to the SC as I'm sure yours will alongside yours as well! Speaking of the SC - hoping that you've finally narrowed down your issue! Keep us posted on how it goes swapping out the FPR. Do you have any way to test fuel pressure at the rail so that you can verify?

PS - man, the GR Corollas sure are sharp little dudes. My wife is still on the wait list - we've been on for almost a year now and still haven't managed to get our hands on one...