Need thoughts... really weird problem.

[Grandavi]

Not sure if this is correct area because its boost related (thinking as an afterthought... )

So, background (for those that don't know), my car is in the shop and getting tuned/upgraded since June last year. The car has a HKS Fcon Vpro 3.3 (7M chipped) and the boost controller is a HKS EVC-S.

Car runs fantastic, however, on the dyno doing the final tune, etc, the car wont boost past 5 psi (tried both a 10 lb and 14 lb spring in the Tial wastegate). If it does it will spool and then jump to 19 psi (turbo cut is set at 19 psi currently to protect the turbo). Makes awesome power.. however.. there is NO BOOST control. Tried changing out the EVC-S solenoids.. no effect.

Thinking that this may be because of either the wastegate is too small (need a 60 mm??) or a manifold issue (I don't think its manifold though).

Anyone have an ideas what would cause this in your opinion? In research mode now to see what the potential issues may be.

Boostcreep occurs when your wastegate cant flow enough to keep up with the engine, which is why I am wondering if the 44mm Tial Wastegate is too small...

(keep in mind... no cams, no head porting at all.. stock head. The NA-side of my tune has the engine running far better than any 7M I have seen so far... )

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
(This is just in case your wondering what's in the car now... not part of the question, but good background)
7MGTE (Wiseco pistons, polished crank and rods, Cometic 1.2 MLS Headgasket) - engine runs like a top!
3" vband DP mated to a HKS 3" catback exhaust with twintip mufflers

No head porting or cam upgrades

HKS Longrunner Manifold (used bought from Leftynridge here on the forums). Lots of reconditioning needed, is now ceramic coated.
Tial 44 mm Wastegate (bought from Leftynridge as well along with a SP6267 .84 ar turbo that is dead)

SPracing 6262 .68 ar DBB Turbo (new and on the car sitting on a 1.75" spacer, 4" intake, 3" vband hotside)

1000 cc ID Injectors
HKS Fcon Vpro 3.3 standalone *7M
HKS EVC-S boost controller
90 MT MK3 ECU (swapped in as my Vpro connects to a 89+, not pre 89)
- kept the ECU for idle timing and AC functions

DM 7MGTE Intercooler upgrade (custom piping done though as the CXRacing version doesn't quite fit properly...)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

 

[atmperformance]

waste gate sticking open? and sometimes suddenly closing?

 

[din904]

44 mm wastegate should be plenty for that setup. First thing I would do is bypass you boost controller and connect wastegate directly to turbo and see what happens maybe try running a 14 lb spring and see what kind of boost you can make. The manifold would not cause the boost to spike suddenly or to not build boost at all. It sound like a wastegate or boost controller issue double check all your vacuum lines going to and from the wastegate and stepper motor.

 

[hvyman]

Ya run off wastegate spring pressure only and then see where your at.

 

[Grandavi]

Tried that... Only 4-5 psi on spring only. Didn't matter if spring was 10 or 14 lb.

It kinda defies logic. Wastegate is only thing that makes sense, but it's anything but normal. Nice smooth curve though on dyno.. A tad over 300 rwhp at 5 psi.

 

[din904]

A buddy of mine had a similar issue and it turned out to be a cheap 90 degree 4 inch rubber elbow on the intake before the turbo collapsing under the suction of the turbo it took about a week before they finally figured it out. I know it's a long shot but I thought it was worth mentioning good look .

 

[hvyman]

Your using the bad turbo?

 

[Grandavi]

No, brand new turbo. It works amazing with the setup, only problem is can't control the boost.

Keep in mind, this is RCTS and they have done a lot of Supra setups... Usually 2j though. I think mine will be the fastest mk3 7m they have built. Normally, they setup everything and are adverse to using anything used (like my original setup is). Reg toyed with it all morning on the dyno trying various things to achieve some boost control, but in the end it's either 4-5 psi or boost cut... No in between.

I really love how much torque this 7m has...

 

[atmperformance]

maybe some 7m is sabotaging your build. but in all seriousness I'd take a closer look at your waste gate, my guess is possibly stuck open and still making that 4-5 psi then spiking when it snaps closed. Also could be some kind of turbo issue as a new turbo can also be considered an untested turbo. I'd say it's not an amazing setup if you're having this issue . at what rpm are you seeing 4-5 psi of boost?

 

[hvyman]

Diaphragm might be torn barely in wastegate.

 

[Grandavi]

I think I am going to just swap out the wastegate with a 60 mm one and be done with it. And the amazing setup has more to do with overall engine performance than with this problem. If you were to take the turbo out of the equation, the 7M is running a lot different than prior to the HKS Vpro. Its a very smooth power curve now similar to what you expect with a 2jz. Will be easier to describe when I get the actual dyno sheets. The NA side of the tune is done. Its hard to explain.. lol. You would have to have the car running beside a normal 7M to see it I guess..

I had a similar problem with the dead turbo where it wouldn't spool and then would hit hard out of nowhere. Thought it might be the wastegate at that point. That's why I am thinking its sounds very much like a problem with the wastegate. Maybe not so much the size as the wastegate itself is faulty. Anytime I have tried to cut a corner and save a couple backs.. wham! Crap costs more ...

Wouldn't be so bad if I was doing this myself.. but I still refuse to work on my own engine. Im just not talented enough..

Kinda wondering if the hole, where the exhaust diverts to wastegate is too small. (just guessing from looking at drawings...)

This is a picture of the wastegate/pipe setup I bought. (Its still similar but cleaned up a lot)

 

[Grandavi]

maybe some 7m is sabotaging your build. but in all seriousness I'd take a closer look at your waste gate, my guess is possibly stuck open and still making that 4-5 psi then spiking when it snaps closed. Also could be some kind of turbo issue as a new turbo can also be considered an untested turbo. I'd say it's not an amazing setup if you're having this issue . at what rpm are you seeing 4-5 psi of boost?

I cant tell you accurately what RPM the low boost comes on because I don't have any dyno sheets in front of me. Will get those today.

The wastegate has been on and off the car four times to examine/test/swap springs. The turbo seems to function properly. (remember though, I am not even close to an expert, so I have to go off of my trust for the shop and these guys have been doing this type of stuff for over 25 years).

Here is the way its setup (piping and this is with the dead turbo, but exact same setup with new turbo)



There is no where that any of the rubber could collapse, its all short with hard piping. The only things I can guess at is that the wastegate is doing something funky.

The only reason I posted here was to see if any of you had seen something like this before to help point the right direction prior to actually tossing on a fairly costly 60 mm wastegate. (which I have no problem doing, but I was fairly certain from initial research that the wastegate was totally sufficient for its task... but I seem to have bad luck buying used parts.. )

 

[Grandavi]

Made a decision and bit the bullet... going to have RCTS check the porting on the manifold, and make sure that its at the very least a 44mm port. If not do some mild porting on it. Going to go with the "omg... how much $?" 60 mm wastegate and have the dump tube reintegrated with my 3" vband DP. Because I am paying hourly labor... in the end its cheaper not to have to have them monkeying around in my bay to solve an gremlin... and just do it right. (If I recall, its going to be the HKS GT2 60mm external wastegate)

 

[hvyman]

60mm is way over kill for that setup. 44 should be more than plenty.

 

[Grandavi]

That's what I originally thought as well. The 60 mm is based on availability. The part is here so I can use it. If I go 44mm I wait.

So the question is... Will the 60 mm hurt? From what I read (remember I'm not an expert by any stretch if the imagination) overbuilding in this area won't hurt performance. If I'm wrong that's a different story. I have been trying to overbuild the car so that what i ask of it won't harm anything, but also really trying hard to keep the parts applicable to each other so that they all work correctly together.

I appreciate any negative comments especially if I'm doing something utterly stupid.

I don't mind wasting a bit of money to do it right...

From my understanding, I will have the best boost control with this size as it is oversized, and longevity should also be excellent. Other than initial cost, I don't know of any negatives.

 

[supranewbie]

Why does it have to be the wastegate and not the boost controller? I've heard a few complaints regarding hks solenoids.

Just reread your first post. You already swapped out solenoids. My bad..

 

[Grandavi]

Already swapped the solenoids. Boost controller was the first thing to eliminate.

With the boost controller disconnected, it boosts "normally" but only runs to a max of 5 psi boost. Already smoke and pressure tested the intercooler and piping as well.

With the boost controller working, the system spikes to 19 psi and then gets cut. Can't control the boost between 5-19 psi. Wastegate spring was 10 lb, now is 14. Makes no difference. It's been apart three times and everything is working as it should.

It's just that if you try to control the boost there's nothing really between the 5-19 psi range. The odd part is how it only runs 4-5 psi on the spring.

 

[hvyman]

With a 14psi spring it shouldn't open at 5psi. It's not possible unless something was damaged inside the wastegate.

Can always rebuild the 44. Nothing wrong with that. Tial sells rebuild kits for them.

 

[7M4EVR]

I have no experience with the fcon vpro but is it possible the way that is wired in could be the problem? U said something about boost cut being set at 19. Is that regulated by the v pro any how, or just the boost controller? Just fishing like i said no idea how the v pro works ive only played with the safc

 

[Grandavi]

With a 14psi spring it shouldn't open at 5psi. It's not possible unless something was damaged inside the wastegate.

Can always rebuild the 44. Nothing wrong with that. Tial sells rebuild kits for them.

That's the issue really, the reasons for this to be functioning like this have been looked at and the solutions have been tried. The way it's setup should run properly, but doesn't. So when you crawl backwards, all the parts check out. There are a lot of "maybe"s but at an hourly shop rate....

I am not familiar with standalone systems and have to have it all explained to me as I go. There is no other 7m on a VPro that I know of, so I have no idea if the VPro is doing this. I do know there are fail safes to ensure I don't kill the engine but any comment by me would just reflect my lack of knowledge.

It's scary when a reputable shop has no idea what's causing the issue because they have never seen anything like it.

I also don't know if the Vpro is set for the boost cut or if its the EVC-S. I do know with no boost control, all I get out of it is 4-5 psi.