The car has ran beautifully upon return from GTM, was returned back to me set at 10psi (would hit about 10.4psi), with the caveat that I need to wait to break in the motor before stepping it up a bit (up to 14 - 15psi). So, current setup:

GTM Stage 0 short block
Minor headwork (ported, springs, shims)
GTM turbo cams
APS ST with GTM Turbo upgrade
External WG (Tial 44) with open dump
Kinetix SSV plenum
APS BOV
Blitz SBC EBC

Hit 2500 mi. on the setup, ready to turn up the boost. Set at 12psi (Blitz SBC settings Auto (12psi), Gain (85), Warning (12), Limitter (12), set on WG).

Car will still only boost to ~10 psi. Adjusted a few more settings on the Blitz with varying levels of boost, same result. Actually, it turns out to be something like this:

Gear/Peak psi/psi @ 6500rpm
1/9.5/9.5
2 /10.6/10.4
3/10.6/10.3
4 /11.4/10.2
5 /12.5/10.1
6 /--/--

Double-checked plumbing to WG, all routed correctly, in great shape (no visible tears), all connections firm and triple-checked. Valve controller on SBC was replaced by GTM (new).

Was advised that there were suspected leaks around MAF and BOV at/above 14psi, those issues have yet to be addressed. Spoke with Sam at GTM a couple weeks ago, suspected that rubber intake accordion tube may be collapsing. So, removed the rubber intake so the GT35R was breathing unrestricted, no change in behavior/boost characteristics, thus ruling out collapsing intake.

You can hear the WG start to crack open around 6psi, and obviously fully open at 10psi (open dump doesn't leave much guesswork as to what's going on below). I do not know what spring is being used in the Tial.

So... I'm at a loss. Anyone that can point me in the right direction as to what to look/how to rule out specific issues would be greatly appreciated.

Seems I'm battling a significant boost leak or EBC issue, but unsure how that would relate to degrading boost w/ increase in RPMs.

 

what EMS do you have? it there is a big possibilty that its not tuned for more PSI and therefore will not boost more.

 

Are you hitting boost cut? Sam set my boost cut at 11psi and if my car overboosts everything gets cut instantly.

 

What is your vacuum at idle? If you have good vacuum you probably don't have a leak and it might be a defective SBC, even though its new doesn't mean its no a possibility.

 

My current EMS is UTEC. But that would seem irrelevant because boost is not controlled by EMS nor is there an interface with the turbo to control boost? Current vaccum at cold start is -14 inHg. However once warmed up the vacuum increases to -17 inHg.

Car runs strong otherwise, AFRs and EGTs within normal limits, not spastic in the upper range. Just... doesn't stay beyond 10psi

With that said, would you suggest searching for a boost leak? Or running the car without the SBC to see how the car behaves? I've tried both auto and manual modes on the SBC, neither has any effect on boost.

 

vac seems good. i say take the SBC out of the equation, disconnect it. you said you dont know what spring is in the tial? you could always just run your boost line straight from the manifold to the wastegate to check.

 

Did GTM tune the motor for 15psi while it was in their shop ?

 

Yes - tuned for 15psi

 

Disconnected the EBC this evening, running only on spring pressure. No change in pressures from that noted above. So... at least for a start, would anyone agree the EBC is suspect (fawked)? If so, anyone have a spare they wouldn't mind letting me borrow for a day?

Otherwise, any addt'l suggestions are appreciated!

 

I had a brand new Hks 6 defective out of the box.When Dave at FunctionTuned tried to turn up the boost nothing happened and it was determined the stepper motor was bad.

 

umm we had a similar issues on one of my friends Z, just check the line going from the EBC to the wastegate, the problem is not on the line itself the problem is on the Banjo Nipple on the wastegate make sure the air will go through the banjo bolt and the bolt won`t block the nipple, am sure no air going to your Top Port on your Waste-Gate.

 

u could alwasy use a solenoid and use the utec to control boost.. i think runnign for 10-14 psi the utec is good enough to controll it
other options would be manual boost controllers... not much choice...
sorry i couldnt help you more that other day bud, but know by know you probably tried most of the suggestions.... bad ebc a possibility...

 

Could be something as simple as a torned/melted vaccum line. I spent hours with a boost problem on my race car...only to uncover a small tear in the silicon line. I think somebody sabotaged it...haha.

 

so you disconnected and the boost is still not going past 10? if thats the case i would think it was not the EBCs fault. something else is wrong. i say pressurize the system to see if you have a boost leak anywhere. i made one from PVC and a coupler that would attach to the inlet of the compressor housing.

 

Set your control to Auto
Boost set to 12 psi
Gain set to 5 or 10
Warning set to 13 psi
limiter set to wastegate which I think is 99
Then go into the utec and set overboost setting to 13 psi
I have noticed with my controller you have to be at least 2 psi over your wastegate spring for the controller to work right.
Now go do a 4th gear pull and see what you get. I bet your problem will be solved. If you use the manual setting start out with low #'s & work your self up or you will over boost.
I think your problem is that you have your boost setting and limiter the same. The warning needs to be a bit higher then boost setting and your gain is way to high.

 

This was purchased from a board member a couple years ago, and it never seemed to work right before the build, either. Still trying to scrounge up another EBC to rule out the Blitz as being at fault/partially at fault.

Visually, they're fine. As part of my checklist, I'll pressurize them with some shop air and double check.

Would seem to me, however, that if the boost characteristics didn't change with the EBC plumbed vs. not plumbed to the WG, then it's a possibility that it's not releasing air into the top port (as suggested above). Thus, as part of the checklist, I'll make sure that air flow through the banjo bolt is sufficient. I'll also use shop air and empirically test the EBC when removed from the car to see if it will hold/release air thru the solenoid.

Will do, tho I do not know how to access the UTEC (yes, I have a laptop and the TurboXS CD); I'll spend some self-tutorial time and make the change as suggested, and report back. Is it necessary to make this change even tho I'm not using a UTEC boost controller or MAP sensor (at least I don't believe I am using a MAP sensor)?

 

I pretty sure you are tuned with the MAP sensor. The MAF gets maxed out real quick. I had the same problems with my Blitz EBC but got it figured out.

Maybe AthenG will chime in, he is better explaining the utec.

 

/\ I'm about to sleep and just saw this thread, I didn't read every post but if the OP is using an EBC then Utec has nothing to do with it. To connect to Utec to set the overboost limiter then just read the manual 2-5 times and things will be a lot easier to follow... I can barely open my eyes to explain how to connect to utec..lol

 

Alright, well.. burned up a Saturday to find a handful of contributory issues:

Crossover flex pipe: found a massive exhaust leak at the flex union. I ended up removing the crossover pipe, cutting out the union, and making a slip joint and band seal clamp, emulating what tig488 did with his APS kit (see pic below). My arms make me look like I'm a victim of domestic abuse, but the leak is sealed.

Catch can leak: performed a pressure test on the system, found a considerable leak at the catch can union. A little cork gasketing to fix that...

Intake manifold leak: The SSV was leaking somewhere around the gasket where it matches up with the lower intake manifold. Found that upon reinstall a metal manifold gasket was reused. Removed metal gasket, cut a new cork one for that as well...

Boost line leaks: As was suggested by previous posts, sure enough both rubber lines from the EBC solenoid running to the WG has splits that wouldn't appear until you put about 8+psi thru the system. Seems that when they were pulled thru the holes in the frame/wheel well upon install, they may have been dragged across/caught on a sharp piece of metal. Ran new rubber lines from the EBC solenoid to the WG and pressurized the lines to double-check integrity. Also assured that air was flowing thru the banjo bolt on both ports of the Tial.

Blitz EBC funked: So if I understand this right, the EBC should put out air to the top port of the WG in aplying resistance against the spring until the desired boost (i.e. 12psi), at which point it would stop pressurizing that line, allowing the spring in the WG to open and discharge the hot side of the turbo, correct? That said, pressurized the Blitz EBC in 'auto' mode, no air discharges from the solenoid, which would explain why the car is running on spring pressure. In 'manual' mode, the thing will discharge air regardless of the boost level input (tried about 30+ settings); each time it would allow air to discharge into the top port up to 25psi, then as the pressure in the line tapered around 11-12psi the servo in the solenoid would 'sputter/stutter', then around 8psi there would no longer be any air dicharged to the top port. Seems that if this were working correctly, it would discharge air to the top port up to the set boost limit (i.e. 12psi), sputter/stutter around 12psi to allow for some resistance against the WG spring, and any pressure beyond the set limit would stop the air from being discharged from the solenoid. On occassion, the solenoid would never allow air to be discharged. Being a pretty bright guy, I've experimented with about 50+ settings today with no success. So, methinks the control module for this setup is dicked...

After making all the aforementioned repairs, the system holds 15 - 20psi of pressure fairly well, much more so than when I first started this morning. Test drive this evening found the car to be much more responsive on boost, and on spring pressure will build quickly to 11psi, tapering to 9.5 - 10psi by redline, which appears normal to me.

Any opinions on the EBC issue? Seems I need to throw down for a new one

 

Good job on figureing it out.