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Discussion Starter · #1 ·
Hello, just wondering if any one can give me any insight on this or point me in the right direction. I have looked thru tons of old forms on potential issues with the vsv and trouble shooting vacuum lines.

I have tested the PT and all VSV, and done a boost leak test. I have tested current's and even went as far as replacing the vsv that I can get my hands on. All actuators open as they should. According to my tuner, we are having issues with egcv and not opening at the right time. Sorry if I am butchering what he said but something in regards of the valve opening to late and not bleeding the exhaust pressure.

We have looked at articles on configuration on standalones, and we have tried following the directions below, and tired different combo's on setting up the vsv rpm range. When we replicated the settings on this article it made it worse.


fyi, i do have my mac valve (boost control) sitting here
Font Automotive exterior Parallel Auto part Rectangle


i have replaced:
90910-12114 : EBV VSV (replaced)
90910-12115 : WG (Mac Valve)
90910-12127 : EGCV (replaced)
25860-46060 : IACV (replaced)

my setup
  • Pro128 ECU supra manual kit
  • Stu twin hybrid garret GT28r setup
  • Upgraded THUK pipe
  • 19-36 lbs actuators
  • Ported OEM exhaust manifold
  • Ported oem Bypass valve
  • ARP head studs
  • GSC s1 Cams
  • GSC beehive w/Ti retainers
  • Shimeless buckets
  • 3port boost solenoid
  • 4inch ETS intercooler
  • 4inch PWR exhaust cat less
  • PWR downpipe cat less
  • PWR pulley kit
dyno sheets
Rectangle Slope Plot Font Parallel



In a nut shell, I am reaching out to SF folks to see if they ran into issue like this. I have tried to trouble shoot this issue for about a 1yr now with of course waiting on dyno's & my tuner.

I am hoping someone in here has a solution or Idea. The car is super unpredictable and sluggish, I need find a solution to bring this back down to 3800 rpm like how the stu's kits are suppose to be operating. Please, someone in here must have ran across this before, My Tuner has pretty much given up, he is still willing to put it on a dyno and re-work to tune if I can find something he didn't think about.
 

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Hi there - while I can't be of any help to your issue, I'm wondering if you are on the stock fuel system since I didn't see it in your modification list ?

Best of luck with your issue, my STU GT28's were very sluggish and laggy too, I was running an old boost controller and was able to remedy the issue with a newer one that controlled boost by RPM (HKS EVC 6), but my car is just BPU.

Have you tried messaging Stu directly ?
 

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Discussion Starter · #3 · (Edited)
thanks for responding, I have a 525 hell cat fuel pump,
1300cc fic injectors
Flex fuel sensor
Radium fuel rail.

I have talk to Stu and he sent me some good trouble shooting stuff but no luck.

I had sp Larry look at it my build and did a dyno session with him but he didn’t want to waste his time trouble shooting.

I have another local engine builder and tuner that took on the challenge but after a few days of street tuning and 5 hours on a dyno , no luck. He said he is willing to look at again but I don’t want to waste his time until I find some different ideas.
This is pretty much my last hope before I rip these things out and go single.

Also no issues with stu’s kit. I think I did to many things at once and I messed something up. Stu has been the man and has helped out a ton. Just don’t get what I did. Everything holds pressure and vsv passed all test. Even did a boost leak test and no issues there. I feel like it’s the freaking egcv valve the vsv is the issue and I replaced both of them and still no luck.
 

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You need to validate that things are happening as you think they're happening. Put a GoPro pointing at the actuators themselves, do a pull. Then compare the time hacks in the video with the time in your ecu logs.

If the ecu thinks it's opening the EGCV but the GoPro shows it's slow or not working ... well there you go.

If you have spare inputs in the your ecu, you might install a pressure sensor or two in the system. Ensure you have pressure when you/ecu think you do.

Something somewhere is lying to you. Basically, PROVE that the system(s) is working as planned. You've tested all the components individually, now need to test them working together as a team.
 

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I wrote that guide on the Link forum you mentioned and have tuned many stock twin/hybrid setups on standalones here in europe. If you have any map files & logs you want to send to me then I'm happy to give you my opinion based on what I can see from that.

A really quick test you can do is put the turbo system into TTC mode. This will allow you to see the earliest and most "natural/mechanical" way your turbo's will want to come onto boost.
If they come on considerably sooner (1000rpm+) in TTC then you know your mapping is incorrect, or you have an issue with VSV's/Wiring/Plumbing etc with sequential system.
If the turbo's come on within few hundred rpm as they do in SEQ , then maybe thats what they will do, or you have another mechnical issue somewhere else.
To illustrate what i mean, take a look at this dyno graph. Same car, same turbo's, same boost target, back to back pulls in sequential vs TTC. You should be able to replicate this graph if everything is healthy.
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Stu's 28 kit isn't common in europe so I haven't tuned that exact combo before, but I do have some data on a GT28 based hybrid twin system running in TTC at 23psi, just so you can make a comparison with yours (although it isn't exactly apple to apples)

Rectangle Slope Plot Font Line
 

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Discussion Starter · #6 ·
Thank you both, and will try filming the actuators and will try putting it in ttc. Mike I will send you map/logs first. Thank you both again for the ideas.
 
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