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Discussion Starter #1
Hey guys....
few months ago I decided to do the eTTC mod, since it was cake and some people like running their cars in True Twin. I wanted to give it a go so I followed the MKIV.com directions. It's all wired right and when I flip the switch the exhaust note changes and when i shut the car off without changing the switch it throws a code (which it should do for odb2). I even hear the release of pressure from the passenger side when the car shuts off.

My problem is the turbos aren't behaving the way they should in eTTC. I get full boost of maybe 13psi @ 3500 rpm then boost falls to 7psi around 4000 rpm. This is even with the spring mod in place. Also I don't think I have ever made over 13psi of boost in eTTC. Shouldn't I be able to hit 18psi like in sequential to redline? Shouldn't I see that max boost at 4500rpm and not 3500rpm? Seems like the #1 turbo is working and not #2

I've read most people have problems in sequential then go to TTC to fix the problem, but what I have hear is the opposite.

I'm thinkin it might be my pressure tank.... but I'm not sure. Is there any real way to check if my pressure tank is going bad? If it is a bad pressure tank there shouldn't be a transition from #1 - 2 in sequential. Is it something else?

I'm a BPU Auto. I have a profec B setup the way ebc's should be set up according to MKIV.com. Would messing with the ebc have any effect being eTTC?
I have the spring mod done and that holds boost in sequential as well so no problems there or with leaks.

I don't know, I'd like to run eTTC properly before saying its not my cup of tea..... :dunno:
 

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Stock Twins King
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You already answered your own question. If you hear the Psssh when turning the eTTC switch, then the tank is good. I use my switch alot, because of road racing. I do notice my car acts up when I release the switch, basically what you say. After sn ECU reset and about 10 minutes, its back to normal. What happens is that there is still pressure on the actuators, and one of the 2 ones sticks open, hence what you have going on. If one or the other actuator is stuck a little, your boost will drop, BUT you will still have full boost after 4200 or so. If you have still little to know boost above this, you have a cracked hose, or something wrong with either the IACV or EGCV. If either one of those are closed, you will never get much higher that 11-12 psi
 

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Discussion Starter #3
Hey Stu, thanks for chiming in.... I was on your website and it provides lots of great info....I appreciate you having the pics up especially. I checked the pressure tanks and the hoses on it. The hoses were in good condition and it did release pressure when i pulled a hose. So the tank is still good. Gonna look at the IACV or EGCV..... is there a fix for them if they're my problem?

BTW stu, you have a really nice supra.
 

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Stock Twins King
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The seq. system is really a well orchestrated system. If any one item craps out if effects everything. It could be a faulty VSV, or a actuator that is going bad. The actuators are a diaphram/air based unit. If there are and pin holes in the they "leak" It is usually not that big of a deal, especially if you are in a constrant driving mode because there is constant pressure all the time. As I recommend to alot of people that are seq junkies, it is a good investment to get a hand pressure pump/gauge. You can test every actuator and the system with this and you can find bad components alot easier. They are under $50. You can pump up actuators and watch how slow they release, or hold. Also a good way to check pressure tanks too. If any of the 2 IACV or EGCV are not working, or opening properly, you will never get full boost. If they are still pressurized, then all you get is "lag" up to 4200 rpm. But still you should get full boost. Blow through both VSV's and make sure you can't blow through them without any power to them. I have a "test" VSV page on my webpage. LAstly, I would do this. Turn on your eTTC switch. Go out a do some 1 or 2 healthy pulls. Stop and pull over and pull the IACV hose going to the pressure tank. "AT THE SAME TIME", (better to have 2 people) have someone peek down at the EGCV actuator rod. When you release the pressure, the rod should close, or "return" Do the same thing for the IACV. This one you can see yourself because it is right there on top. It is possibe that you installed the eTTC wrong, and it is not shunting out the VSV properly. This would be your problem as well.
 

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Discussion Starter #5
Hey stu,
just a little update.... did 2 pulls in eTTC this morning..... was doing about 30-40mph, punched the throttle, car down shifted (auto) built boost to a little over 7psi then dropped as rpms went over 4k. This has happened to me in sequential on a downshift on a few rare occasions. I will try to check the actuators and the EGCV/IACV when I have time this weekend.

Can you place a link to the VSV test page.... I've tried looking on your FAQs and TECHs section but I just can't find it. I really wanna fix this.... its getting annoying not having everything work as it should but at the same time I'm learning alot.

Thanks again
Mike
 

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Stock Twins King
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http://www.97supraturbo.com/Supra Scans/WastegateVSV.pdf

This is a generic test proceedure for all VSV's. It is pretty simple, except you need to remove them to do it. I suppose you can do it in the car, its that you need to apply 12V across the terminals. No 12V+, they are closed, can't blow thru. 12V+ applied, it opens and you can blow thru the 2 nipples. Sounds like your wastegate VSV has gone bad.
 
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