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Diligence always pays off, now you can really enjoy your SC.
Thanks Bill! Make that three years of diligence as I was still learning about this turbo system.
The biggest lesson that I have learned overall with this swap is to go through and test every aspect of every used part before getting it into the car during assembly.
But there are so many parts and this is something I had no idea might be an issue. Live and learn as they say!
Makes we wonder how many single turbos have been installed on 2JZ's because of the clogged line. Glad to see you got it worked out!
After you get some time on the new turbo's you can look into the spring mod to make the transition smoother and if I remember right it helps with longevity also
Makes we wonder how many single turbos have been installed on 2JZ's because of the clogged line. Glad to see you got it worked out!
After you get some time on the new turbo's you can look into the spring mod to make the transition smoother and if I remember right it helps with longevity also
It does seem to be possible that one of these vacuum/pressure metal lines getting clogged could be the beginning of many 2nd turbo failures leading most people to ditch them for a single, yes.
Thank you! It was a relief when it finally worked!
With this build I won't be upping the boost or doing any spring mods. The effort put in to make it as CA emission passable as possible would be undone at that point. With another SC build I'd take an entirely different approach though.
However, you bring up a good point and the longevity of the 2nd turbo (and the effort needed to replace the whole system each time) is a concern of mine.
To that end I still need to do a hard line pressure test for the Exhaust Bypass Valve VSV connections because that is the part of the system that Toyota and Hitachi designed to begin pre-spooling the 2nd turbo (into a "free-wheeling" state if I am using correct terminology) specifically so that once the EGCV and Intake Air Control Valve open up to allow the 2nd turbo to boost it doesn't suddenly get slammed from 0 RPM to 20k+ RPM in just a second.
That EBV VSV failing or the pressure from it not engaging before the 2nd turbo is allowed to fully start spooling up and building pressure can over time cause damage to that 2nd turbocharger and is definitely in part what has contributed to many blown #2 turbos.
However a quote from Chris Wilson @ SF was that it was still over-boosting that causes the majority of #2 failures.
I still have one little quirk left with the turbo and that is:
When I left off boost from #2 engaging sometimes... even if 20-30 seconds have passed... I occasionally get a little ("ooooo...") noise from the right side of the engine that is not the factory blowoff valve.
I have heard this sound for the last three years. I don't usually hear it when the 2nd turbo is coming into full boost. I can usually make it go away by backing off on the throttle so the the RPMs are well back into the Turbo #1 range only. Then when applying boost again the 2nd turbo transition is seamless.
I certainly hope that not solving the EGCV valve issue did not cause shaft twist on my brand new #2 CT12B turbo while it was JUST broken in. I hope it's just down to an old, lazy or sticking Intake Air Control Valve actuator or lazy, old and sticking EGCV actuator.
If I had to guess I'd say it might be the EGCV actuator being lazy... even though it works now as it is getting the pressure it needs at the right time.
...
Then again since I did hear it for the last three years each time the EGCV was fully closed any time I tried to engage the 2nd turbo (with the old turbochargers) maybe it has something to do with a malfunction in the (turbo)IACV actuator or the Reed Valve inside it.
......
My plan of action now is:
--Test the EBV metal line paths to be sure there are no blockages (I have already verified that the nearly brand new VSV and the wiring going to it are fine)
--Remove the upper metal lines, blow them out and clean them to be sure they are fully clear
--Replace my old used Intake Air Control Valve with a brand new one that I bought last year. A new Reed Valve and gaskets will go into it as well.
--Replace the EGCV actuator. Hopefully. I was able to order a new one with the iron assembly attached from Japan. At least that's what it seemed I was buying. Hopefully it's not just the iron housing and nothing else. I already have a spare one of those with no actuator.
--While I'm messing with the upper metal line assembly I'll put new rubber lines in for the pressure tank connection to the other side of the engine. Never a better time to just do it while they are accessible even though they are currently in perfectly good shape.
......
Aside from the turbocharger system I have re-connected my HKS turbo timer now that I know it was not the cause of the blown igniter issues some months back. Sometimes when in a rush it is good to have the automatic system ready to allow the oil time to cool down after you've left the car.
I've also got a new A/C triple pressure switch (Lexus P/N 88645-20040) coming in soon which I'll have installed at my local dealer. My original one seems to be tired when first starting up. Since it now communicates with the climate control ECU and with the previously unused two pins also acts as one of the triggers for the auxiliary cooling fan relay (identical to how it works on a 1993-2002 Supra Turbo) it will at first cut on the fans... but quickly cut them off. Then turn them on... and quickly cut them off.
That part number is the same A/C pressure switch used by the Toyota Soarer 1JZ-GTE manual and automatic models which have an auxiliary electric radiator and condenser fan relay control circuit that is very similar to the one that I've recreated from the Supra TT so I know it will work for this purpose. The pressure switch for the Supra TT is 88645-20050 but I felt it best to stick with the SC300/400 part in this case.
I think that pressure switch is just getting worn out since it's likely original to the car's manufacture date. Replacing it should make the fans turn on and stay on long enough for the switch to detect the correct amount of pressure drop in the refrigerant before cutting the fans off again.
Once the car is fully warmed up with the A/C on I don't have the twitchy erratic on/off of the auxiliary fans. It only seems to happen if I turn on the A/C when I've just started the engine and everything hasn't warmed up to full operating temperature yet.
......
The car drives MUCH better now with an EGCV VSV getting pressure. That's a big win in my book. I just need to sort out this last bit to be 100% certain any boosting and actuator issues are truly solved.
......
Edit: I think this may be the "ooooooo" sound that I was describing above. According to Stu Hagen in this thread below it is likely to be the Reed Valve that is sandwiched on top of the Intake Air Control Valve and its metal cover (with two gaskets).
Your reed valve has bent slightly.........an easy fix. See the left Reed, it is bend. It vibrates which makes the moaning sound. Just like any reed type on instrument. Sounds like a deep Oboe.
Originally Posted by Stu Hagen
Yes, you can bend them slightly.They come out after removing 2 screws I think. Try not to bend the upper silver pieces. I have re-bent them back before. They usually do this over time, or maybe a big boost spike where you let off quickly causing a huge back pressure surge. I have taken apart dozens of these and this is actually quite common to see. No sense buying a new one. Besides, I do not think you can buy just the reed, you would have to buy the whole IACV assembly.
To note, this is a thread that predates the finding that you actually can buy just the Reed Valve and gaskets themselves. They're an easy replacement to do and do not require removing very much to get an old one out and install a new one.
I'll do this but annoyingly I already installed a new one last year during earlier trial and error diagnosis. If it is actually what's making the noise then maybe something happened to it while the EGCV actuator wasn't being engaged for the last couple of years.
Further posts on this topic of a Reed Valve issue in the 2JZ-GTE sequential turbo system:
Well, I got the main metal vacuum line assembly over the turbochargers slightly out of the way and removed my Intake Air Control Valve's "Reed Valve" for inspection. It was only replaced about a year or two ago and it looked practically brand new with no abnormal bending of the thin metal strips at all. I compared it to the brand new one that I have on standby and the two looked virtually identical.
With the control valve's top cavity open to see I again tested its actuator with my Mityvac hand pump and noted that the internal plate closed completely with no pressure applied and opened fully with 7.8 PSI of pressure applied. It didn't stick or hang up at any point.
I also re-tested the EGCV actuator directly again just to be absolutely sure there was no sticking or binding with it. I didn't detect any.
I reinstalled the Reed Valve, put the cover back on and tightened the four nuts (I believe it's less than 3 ft-lbs that is required for the nuts or maybe just 78 inch-lbs) and reconnected all the vacuum lines.
I took the SC out again and sure enough occasionally after a little pre-spooling or light full engagement of the 2nd turbo that same issue with the "ooooo" sound and a slight temporary loss of power would occur. I could always make it go away by disengaging the clutch and backing the RPMs way below 3500 before rev matching and getting into gear again.
It's not the sign of a bad 2nd turbo since both newly rebuilt CT12B's have barely 200 miles on them. When I engage the accelerator with intent there isn't any issue getting into full boost in turbo #1 and transitioning into full boost in turbo #2. In other words, there is certainly no "death whine" from a bad turbo.
It's more of a light throttle or part throttle issue where the (turbo)IACV and/or its Reed Valve are bleeding off extra pressure when they shouldn't be. Something like that.
I'm able to drive the car much more normally than I have been able to in the past three years thanks to the temporary T-splitter and hose bypassing the metal line that leads to where the EGCV VSV hose *should* be connected. I've just still got this figure out to truly call it solved.
......
Without any other theories to go on right now I think there still may be an issue with the blockage in the metal vacuum & pressure lines that go on top of the turbochargers.
I believe that fully cleaning them out will do something or at least give me a proper permanent fix for the EGCV VSV connection.
Everything else in the system has been tested and that's already got one blockage that I have temporarily bypassed so maybe the only way to solve this is to get every one of those lines blown out with shop air and possibly cleaned with something that I can spray inside and then dry out.
These aren't like EGR passages that get carbon from combustion and exhaust built up. They can't have debris in them that might clog up a VSV or one of the internals of the actuators. Does anyone have recommendations on what safe and easy to dry cleaning agent might be good to use in these very small metal air lines?
The short of it is that I eventually got some of the thin nylon weed whacker line that I had previously used to run through my SC's four sunroof drain tubes, marked the very end with a permanent marker (so that I would be able to know immediately after removing it if any part of it had broken off) and ran it through the blocked metal pressure line that is supposed to connect to my EGCV VSV's inlet port.
That cured the line block issue. I did my best to make sure that no part of the obstruction was left in there and found nothing remaining. I'm still not sure what it was but it broke through easily even though 8 PSI of pressure wasn't enough to break it loose.
Then I put everything back together correctly and drove the SC. The 2nd turbo came on as it should just as before!
...
That just leaves the low-throttle/part-throttle lower RPM (2100-3800 RPM or so) "ooo" noise and temporary lack of boost from turbo #1 until I let off the throttle, blip the throttle to make the factory BOV make it's "PSSSH" noise before getting on the throttle again for normal full boost in turbo #1 all the way into the turbo #2 transition.
Long story short... after doing much more testing of as many of the metal lines as possible and a mountain of deep-dive search into sequential turbo issue threads on SupraForums I amassed myself a pretty dense text file of advanced troubleshooting information to work from.
It's not easy to guess the diagnosis but while I have a totally healthy transition from turbo #1 to turbo #2 now I still have some issue with an actuator or turbo VSV not quite allowing all valves to seal completely after dropping back out of turbo #1. Or really... I don't even have to go into turbo #1. I just have to accelerate below the 3800-4200 RPM transition point (moderately if I like) from 1st to 2nd and then into 3rd. By 3rd gear even with light throttle I'll experience the issue where I have to let off throttle or blip slightly to let off any boost in the system before I can build proper full boost again normally.
Technically I think I had this issue before I fixed the #2 transition issue but it was never before this predictable.
However it's not an issue at all if I am accelerating HARD with full intent to go fast. In that case the boost just keeps on coming. It only happens when driving more moderately.
.....
I ordered new metal gaskets for the (turbo)IACV and front metal charge pipes and pulled out my spare brand new Intake Air Control Valve and a brand new Reed Valve and two new gaskets for it. When they came in I got to work removing the metal pressure line assembly and all the charge piping on top of the turbochargers.
I removed the metal line assembly and ran my weed whacker line through *every* tube and then I pressure tested every single tube with my MityVac tool to ensure there were no blockages left. There were no others found apart from the one blocking the EGCV VSV pressure connection that I had already cleared out previously.
Then I removed the old but tested and perfectly functioning Intake Air Control Valve unit. With that out of the way per the TSRM instructions I pressure tested the EBV (Exhaust Gas Bypass) actuator that is bolted onto the back of turbocharger #2. It's certainly not a new actuator but it seemed to do exactly what it should be doing based on my tests with the MityVac tool.
With that I got the very rear-most metal lines fitted to their hoses again (which I did inspect to make sure they were still in good shape-- they were after only 6k miles or so of use since new).
Then I installed the brand new Intake Air Control Valve unit, new Reed Valve and two new gaskets and put all the upper charge air piping back on with new metal gaskets in place of the ones I had just removed.
Then on went the rest of the metal line connections. A double-check of all my work followed just to be sure I hadn't forgotten anything.
The SC got a fresh oil change as well since the new turbochargers had a couple hundred miles on the last oil.
....
I took the SC out for a drive after all of that hoping for a change but... nope. I still have that odd low RPM boost issue and "oooo" noise seemingly coming from the (turbo)IACV area by the time I hit third gear... unless I am accelerating flat out with full intent.
On the plus side though I have full use of both turbochargers now an I have a healthy transition from #1 to #2!
--At this point based on my deep dive research the issue could be one or more turbo VSVs that work but which have resistance out of the acceptable TSRM range. I can still test for that just to rule out the possibility.
--It could also be a slightly sticking or slightly lazy to close Exhaust Gas Control Valve actuator or Exhaust Gas Bypass Valve actuator. Neither are available new any longer so what I've got now is what I'll be sticking with.
--It is not a sticking or lazy Intake Air Control Valve Actuator because I just installed a brand new one and it acts exactly the same as my old used one that tests well.
--Further it isn't the Reed Valve because I replaced that on the old (turbo)IACV assembly a while back with no change and I installed a new one on this new (turbo)IACV assembly with no change.
--I'll give the temporary TTC mode a try again now that I know the EGCV actuator is getting correct pressure from the line. I anticipate that will go smoothly and deliver linear boost exactly as it is supposed to.
--Finally I'll do a full pressure holding test on my pressure tank even though I bought that as a brand new part (though from a forum member and not a dealer).
But after testing the ohm reading of each turbo VSV (despite them all being brand new when I put the engine together) and checking that everything is fine in direct hose to actuator TTC mode I think I'll have run out of things to test. All of my hose connections have been verified to be in the correct configuration and all of the hoses are practically brand new.
If I can't find anything else that is an "Aha!" from any of those last tests then I'm just going to enjoy the SC as is with the little flaw. It could just be that my EGCV actuator or EBV actuator are mostly fine but not at 100%.
Having use of both turbochargers now is huge so if it's a little quirk to live with in sequential mode I can deal with that. Or I can always use TTC mode but I like sequential.
...
The only other thing to report is that my driver's side mirror went floppy from the clip inside it coming loose.
I “bandaged” the mirror by wrapping it in some blue painter’s tape for now.
I managed to get a new mirror on order that I can transplant my heat & memory wiring harness into and the heated mirror from my original assembly. Then I'll keep the original as my spare once I do a DIY fix for the broken internal spring retainer.
I had already replaced the passenger side mirror with a new one several years ago due to having the same issue.
....
All in all I feel like the SC is very close to being sorted out now!! It drives so well with the transition issue fixed (the second surge of power is great!) and there are only a few very minor things left to address
Kahn you are well on your way my friend! Soon enough all you're going to be able to do is drive and enjoy this bad boy for what it is.
Originally Posted by Barbary
Yes! Thats what its all about 👏🏻
Thanks guys!!
For the most part that's already what I've started to do after the last few big jobs (IGF grounding issue fixed, better alternator installed, aux cooling fans and control upgraded, new turbos, #2 turbo transition issue fixed).
There are several small things left to do and one big thing later on (fixing a slight leak from one edge of my used lower oil pan-- I have a brand new pan on standby to address that eventually... and getting my gauge cluster's speedometer and tach motors serviced) but I feel confident taking it long distance now. It's pretty much back to its reliable start-and-go-anywhere self again
I need to get some shots of it out in the wild finally! Even excluding repairs to the SC things have been so stressful for me in general that I've hardly had a chance for quite a long time now but I'll change that now.
This build thread needs more than just pages of test results, servicing pictures and electrical diagrams!
haha after everything you and this car have been through it's provided a wealth of knowledge to on-lookers in the future! Like you said, the beauty of these cars is that if you set them up right they truly are turn-key GT cars that beg you to get them out on the road. I'm glad to hear you're enjoying it and I look forward to seeing more pictures of you out in the wild with this thing!
haha after everything you and this car have been through it's provided a wealth of knowledge to on-lookers in the future! Like you said, the beauty of these cars is that if you set them up right they truly are turn-key GT cars that beg you to get them out on the road. I'm glad to hear you're enjoying it and I look forward to seeing more pictures of you out in the wild with this thing!
I hope mine treats me like a turn key GT car with 600hp lmao
haha after everything you and this car have been through it's provided a wealth of knowledge to on-lookers in the future! Like you said, the beauty of these cars is that if you set them up right they truly are turn-key GT cars that beg you to get them out on the road. I'm glad to hear you're enjoying it and I look forward to seeing more pictures of you out in the wild with this thing!
I know the posts are sometimes long but I do hope the journey on record and troubleshooting information helps some people! Yes, done right they're great GT cars that will reliably take you anywhere.
I will do my best to get some pictures of it out there finally, Rudy! I have a catch up to all those lovely pictures of your red SC and your Cressida before long!
Originally Posted by silentkill
I hope mine treats me like a turn key GT car with 600hp lmao
After all of your hard work I think you will get your wish! What I have always heard is that it's only past 600-700whp that it's not easy to keep that turn key reliability with JZ turbo powered cars. But I think that's just an arbitrary number range. Gerrb seems to do very well with his cars and his least powerful automatic SC that he drives often is right around 940whp.
The thoroughness of the entire engine setup and especially the ECU type and quality of its tune make the largest difference from what I have learned.
With my SC I didn't tune the engine at all and that was my way of keeping it "turn key reliable" but as a tradeoff I do have only mild horsepower (300-310whp by my un-dynoed estimation). Then again to me that's a massive improvement over the 225hp NA stock engine with a totally different power and torque curve. My stock GTE engine computer may be a limitation but I'm relying on all the work Toyota put in having tested all its programming in a wide range of conditions and environments.
Focus on getting good and well dialed in tune maps made for your ECU. I think other than the rest of the engine being sorted out with good parts that's the real secret behind keeping these engines reliable.
....
Something else is the tuning philosophy: In America we tend to want to tune to reach a specific number... or higher than that number as a bonus. In Japan the tuning shops tend to take the customer request for a certain power level into account but they instead tune for the best real world use even if their peak power and torque numbers are a little below the customer's requested numbers that they wanted to hit. And this is very common accepted practice there. Rather than hitting a specific power number as a #1 goal their emphasis is far more on how the owner intends to use their car and what is currently holding it back from doing what they want it to be able to do more of. At the same time they take the strengths and weaknesses of the engine (as configured) and the fuel grade into account and they tend to want to stay a bit on the safer side with their custom maps so as to best preserve engine longevity and health over all the conditions they're simulating for.
I think your new engine is going to do really well and treat you really well!! I'm looking forward to seeing the result of all your hard work!!!
Thank you for the nice compliment, and awesome commercial to post! I always love this thread and look forward to you being able to enjoy that beauty here real soon!
I know the posts are sometimes long but I do hope the journey on record and troubleshooting information helps some people! Yes, done right they're great GT cars that will reliably take you anywhere.
I will do my best to get some pictures of it out there finally, Rudy! I have a catch up to all those lovely pictures of your red SC and your Cressida before long!
After all of your hard work I think you will get your wish! What I have always heard is that it's only past 600-700whp that it's not easy to keep that turn key reliability with JZ turbo powered cars. But I think that's just an arbitrary number range. Gerrb seems to do very well with his cars and his least powerful automatic SC that he drives often is right around 940whp.
The thoroughness of the entire engine setup and especially the ECU type and quality of its tune make the largest difference from what I have learned.
With my SC I didn't tune the engine at all and that was my way of keeping it "turn key reliable" but as a tradeoff I do have only mild horsepower (300-310whp by my un-dynoed estimation). Then again to me that's a massive improvement over the 225hp NA stock engine with a totally different power and torque curve. My stock GTE engine computer may be a limitation but I'm relying on all the work Toyota put in having tested all its programming in a wide range of conditions and environments.
Focus on getting good and well dialed in tune maps made for your ECU. I think other than the rest of the engine being sorted out with good parts that's the real secret behind keeping these engines reliable.
....
Something else is the tuning philosophy: In America we tend to want to tune to reach a specific number... or higher than that number as a bonus. In Japan the tuning shops tend to take the customer request for a certain power level into account but they instead tune for the best real world use even if their peak power and torque numbers are a little below the customer's requested numbers that they wanted to hit. And this is very common accepted practice there. Rather than hitting a specific power number as a #1 goal their emphasis is far more on how the owner intends to use their car and what is currently holding it back from doing what they want it to be able to do more of. At the same time they take the strengths and weaknesses of the engine (as configured) and the fuel grade into account and they tend to want to stay a bit on the safer side with their custom maps so as to best preserve engine longevity and health over all the conditions they're simulating for.
I think your new engine is going to do really well and treat you really well!! I'm looking forward to seeing the result of all your hard work!!!
Very interesting insight. I would have to agree with that ideology as well. Rather have my car be under my goal and just work every day.
It's going to one of the best supra tuners in my area so im feeling pretty good about it!
06-28-21, 05:30 AM
