Dropping boost at high RPM? Help
 

Calling all turbo gurus! This is my first turbo car. Looking for some input.

Its going to be a LONG weekend for me, my car is out of town at a very reputable dyno tuning shop and they are having some issues with my car.

Cliff notes of my build: stock block, 6MT, 6758 EFR turbo, 700cc DW inj, DW 300 pump, flexfuel, EcuTec. Was on Delicious Flash&Go for about 3 months following the turbo install. Nothing against Zach or Bill, but I think we got it as close as it was going to get without actually rolling it on a dyno. Was having very frustrating idle hunting, stalling and low throttle hesitation.

So I dropped the car off Tuesday evening to get a full dyno tune on 93 and e85. Full day of tuning Wednesday yielded weird boost readings while just on wastegate pressure. Inconsistent boost building and bad boost droop. See dyno sheet below. We were both thinking it was the wastegate actuator so I overnighted a new Turbosmart 10psi wastegate actuator. Thursday was already scheduled for another client, mine went back on the dyno today around lunch and the new actuator didnt fix the problem (I hate throwing money at problems). So by the end of today, still dont have any idea what is causing this issue. Monday morning hopefully we will find out more.

Dont want to call the shop out, they've been great so far. Just here looking for information.

TIA!

Sam

http://i.imgur.com/IQ0AvFZ.jpg
http://i.imgur.com/6x3YGLU.jpg

Have you made sure any silicone tubing routing air into the compressor side isn't collapsing under vacuum? If it's not heavy duty reinforced tubing it could be collapsing under load creating a flow restricrion.

Next thought is if there is any pinging or knock occuring? When they had it on the dyno to tune were they seeing any knock indicators to show why the ECU may be dumping the boost or advancing the timing?

Just food for thought from 10 years on playing with SAABs.

Sent from my SAMSUNG-SM-G870A using Tapatalk

I appreciate the input @NahumCC. Those are excellent theories. All of the charge piping and intake have very close fitups (1/8-3/16" gaps). So having a silicone collapse would be impossible. And I am not sure if my tuner is seeing any knock. He's about 2 hours drive from me and his lead tech gives me pretty frequent updates but i don't know specifics like that.

I'm wondering if this is a flow issue. They mentioned looking at the recirculation valve (BOV located on the compressor housing) Monday morning. My brain is fried. The obvious boost leak is not there and no vacuum leaks either.

Not sure what you mean by the gaps as close fit ups unless that's where you are placing the clamping bands.

What I was trying to get at is maybe it's that the steel bands within the layers aren't strong enough to keep a collapse from happening on t he intake hose to the compressor inducer.

You tuner has a good point to take a look at the diaphragm of the integral BPV on the compressor housing (can't see it from the picture).

Another thought I had was how are you controlling the wastegate? Spring and Ball MBC or a EBC? If MBC then maybe the spring is to weak. If EBC, then may need to check power to it and it's mapping (if it's fancy enough to be integrated with the ECU).

Sent from my SAMSUNG-SM-G870A using Tapatalk

Also, is the integral BPV pneumatic or electronic solenoid?

If pneumatic it needs a signal line to keep pressure pushing down onto the BPV and vacuum to pull it open quickly. Best tap location is the manifold after the throttle body because it's internal spring should be strong enough till the total intake volume is charged but as soon as you cease the boost demand you want the quickest vacuum pull to open it and prevent a compressor stall.

Sent from my SAMSUNG-SM-G870A using Tapatalk

The charge piping and intake are aluminum. All of the piping was fabricated to be very tightly fit up so just slip silicone couplers and hose clamps could be used. There are no silicone hoses or elbows. All of the clamps are tight. No boost leak in the charge piping or FMIC.

Wastegate is controlled for the stock EFR Pierburg EBCS. Harnessed to the EVAP connector and my AEM Failsafe. My tuner can't get consistent pulls on just wastegate pressure so he hasn't begun dialing in electronic boost control. I guess the former has to come before the latter.

The recirculation valve is pneumatic. It gets plumbed to a vacuum line off of my brake booster hose.

@NahumCC

http://i.imgur.com/IJk2gWJ.jpg

Sounds then that once the EBC is dialed in you'll be fine. Your basically running a linear push signal from the compressor to the wastegate. The modulation is needed from the EBC to keep the wastegate shut.

Sent from my SAMSUNG-SM-G870A using Tapatalk

I get that, that makes sense. But if you have a 10psi spring in the WG and you leave the EBCS unplugged. You should be able to hit 10psi and maintain it just off the wastegate alone. Im only making 4psi at redline with a 10psi spring so something has to be off.

Im putting my faith in this tuner who tuned 15 FRS/BRZs last month alone and is a EcuTek and Haltec master tuner. Im trusting he knows his shit, Im just so confused by this symptomatic issue. (Im sure he is pulling his hair out as well being almost 2 full days in already).

You also have to consider the volume of exhaust and flow rate (the a/r ratio of the turbine housing) at the rpm where the wastegate spring isn't keeping up. PV=nRT says if the volume the exhaust dumps into remains the same and if T (EGT in this case) and n (mols of air) are increasing that P (pressure) has to climb leading the wastegate to blow open in the lack of a control source to counter that force.

Sent from my SAMSUNG-SM-G870A using Tapatalk

Internally gated turbo and the bov is right at the turbo housing as well? Sounds like an interesting flow design... Subbed to see outcome. This is y I always go external wg and vent bov. It sucks being on a dyno and having to take her down for work, been there several times and I feel your pain. Gl man

I can almost follow that but I wont pretend to know what all that means haha. I know I have a .64AR turbine housing. I thought maybe I have an exhaust restriction since I dont have a full 3" exhuast. But I have a 3" downpipe to an Invidia OP (60mm) to Invidia resonated FP (60mm) and Invidia N1 (60mm). No cats. No exhaust leaks. All new gaskets.

Thanks! The EFR has been out for a couple years but is a tried and true design. Pretty wizbang turbo technology. Titanium aluminide rotor, dual ceramic ball bearings, oil fed, water cooled, forged milled compressor wheel, IWG, integrated BOV, integrated EBCS, cast stainless turbine housing, and even a location for compressor wheel speed sensor. Very high end stuff here. Also available with EWG and twin scroll. :w00t:

The yellow boost line looks good. A bit of overshoot on spool, followed by flat boost and then it tapers off most likely due to exhaust pressure being high, making it harder to keep the wastegate closed.
This is what I would expect to see on a car with small turbo(s) and a MBC.

If you can make it do that all the time, nothing is wrong and you need some boost control.

Blue looks to be wastegate pressure only and the other 2 could be due to EBC not being setup well.


If you want to diagnose problems, first do a boost pressure test to make sure the intake is holding pressure. IMO, its critical in a turbo system to ensure everything holds pressure, if there are any leaks you can waste countless hours trying to look for a problem which doesn't exist.

Next, bypass the EBC and connect the compressor outlet pressure directly to the wastegate.
It looks to be easily accessable from your picture so should be easy to do.
You should watch the wastegate actuator arm and ensure it is moving as expected during the dyno pull to verify that its working properly.

If this fixes your problem, your EBC could be connected incorrectly or faulty (or just programmed badly)

If not, you need to look at the pressure bypass valve to make sure it is correctly connected (as suggested above) to the engine side of the throttle body. This needs pressure to keep it closed, without this pressure feed the boost pressure will push it open, leaking the boost.
This means if it is either not connected, or connected badly with a hose which sometimes blocks/kinks you will not get good boost control.

Those are the most likely reasons for poor boost regulation.

If that doesn't get you where you want to go, you will need to provide more information. Namely data logs which will show AFR, timing, knock correction etc.

Actually, if you look since about the mid 2000's you'll see the integral BOV as part of the compressor housing has been around on the common factory turbo's from Garrett and Mitsubishi in larger numbers.


The benefit of having moved the BPV into the compressor housing goes to the point above when I mentioned the vacuum signal to pull open the BPV should always be after the throttle body in the intake plenum. Having the BPV in the compressor housing puts it closest to the source where any compressor stall would do the most damage and provide the most beneficial path of least resistance.

That's pretty typical behavior with those turbos, they have a really crappy IWG canister design. I've done dozens upon dozens of cars with those turbos and it's always the same story. When we put an EWG housing on it and run an external gate... no problem, and then the turbo is decent.

I guess I understand this concept. And I suppose this is less important than the wastegate.

I am one of those candidates, on both a 2rz and 2jz platform. I've bought a brand new expensive ass Turbonetics with an internal gate and after multiple times having to come off the dyno (at 2 different shops even) from from spike or drop in boost levels that were unmanageable. Then I picked up a used journal bearing Garrett, and a Tial 44, moved the Tial Q closer to the tb with a better ebc, and suddenly, everything worked like a charm. Not saying that's what's going on here exactly, there's far too many other things to go wrong and I'm guessing it's not the bpv.

Yeah, I think that's what my tuner is currently struggling with is getting consistent boost at a given RPM. From the updates I have gotten, they haven't even started boost control with the EBCS until they pin the erratic boost behavior with just wastegate pressure alone. I sent them a brand new Turbosmart actuator and it didn't help. That's good advise though, thank you. Ill ask my tuner about bypassing the EBCS all together Monday and just hooking the boost reference directly to the WG. I know Monday morning he is going to tackle the recirculation valve and verify it is working correctly.

http://www.turbosmartusa.com/wp-cont...09/IWG_uni.jpg

Hate to hear that! Ah! well... We can rule out the canister anyway as it has a aftermarket one now. I suppose its always an option to close the internal gate and weld on a Tial 38mm EWG if there are no other solutions.

:( Hope I dont have to go to those measures to get it run right, I am already pushing close to $10k on this build.

Thanks again for everyone's input and advise. Its greatly appreciated.

Sam

Your idle issues are because of that sharp angle right at the MAF sensor....

To really rule out the EBCS, you need to completely disconnect it from the system, and run a direct line of boost into the actuator. Th EBCS even if unpluggled will interfere with the boost signal unless completely bypassed from the system. Also, IWG systems are famous for boost tapering down at higher RPMs.

Hard to tell from from the photo I posted, but my MAF is located behind the driver side headlight. Air filter is in the front bumper next to the washer bottle. The intake is fairly straight.

Damn. Well, Im glad you posted because I really dont have the experience to have known that.

From the updates the shop has given me, they worked out the idle issue. But the inconsistent boost engagement is what is slowing him down. Im hoping that boost control added after the fact will alleviate most of that boost droop at high RPM. Crossing my finders that the inconsistent boost in the dyno sheet I posted is direct result of a bad ECBS or recirc valve. Thanks for the input @Sportsguy83. I should have more data and information Monday. Hopefully a resolution and a well tuned car :thumbup: Because I'm still in a rental car. :mad0260:

Sam

http://i.imgur.com/dx7UOBl.jpg

@NahumCC Heres a shot of typical fitups.

http://i.imgur.com/CT4FFsh.jpg

I'm sorry, I thought it was below the pipe, right at that sharp angle before the throttle.


Good luck man, I hope it gets resolved rather easily.

Your solution is right here:

https://www.treadstoneperformance.co...rbine+Housings

So, tried to collect the car today but it isnt done yet. Still not tuned on E85. Still has weird boost building issues. They pulled the recirculation valve and everything looked fine. They hooked the wastegate actuator up directly to the compressor cover outlet but it didnt modify the behavior. They are getting more boost off the wastgate now though so thats good. It is hitting the 10psi (wastegate spring pressure, no boost control) and tapering down to 8psi near redline. It is putting down 300whp on 93 so I cant complain.

I suspect I have a vacuum line issue. My recirculation valve is seeing vac/boost from a tee fitting on the the brake booster. Which also has a tee fitting off of that branch for the AEM Failsafe. Which all of those lines are from previous projects. I bet a vacuum block and new reinforced silicone hose would make the recirc valve more consistent. Thats an obvious one to look at, right?

Ill pick the car up kinda "as-is" for the time being. Ill have to schedule another day or two next month after I tinker around on it.

That's just normal with those IWG housings -- they are junk. I have dozens upon dozens of datalogs from dozens of customers with these turbos, looking like this boost curve.

https://lh3.googleusercontent.com/-W...2/junk_efr.jpg

We've put an EWG housing on the same turbo, no problem. lol

This is the reason I ultimately shyed away from a Full-Race kit on my S2000. Too much fear of having no way to properly control boost with the twin scroll IWG.

This makes me sad.

You and me both. Being new to the world of FI. I thought the IWG EFR was the way to go since its an all-in-one packaage and thought I would actually save a bit of coin with less parts involved. wompwomp.

In all honesty, this isnt a race car, or a dyno queen. A few PSI off the top of the rev range isnt going to make much of a difference to me. I was able to walk a new M4 last month and thats all I need to be happy haha.

Havent Checked that kit in a while, dont they offer an EWG option too?

Edit; just checked theyre all EWG lol

If this doesnt show up in "come race me bro" then ill be sad.

Yeah apparently they wised up and switched the kit from IWG to EWG. Too late now, I love my PTUNING kit.

Dont blame you, both amazing kits (now).

So I got the car back and am EXTREMELY happy with how this thing feels. Drives beautifully now. Putting down 315whp on 93. Went back to stock injectors. Some diagnostic work has determined I have some minor mechanical issues with how my turbo system is set up. Hal at Dynosty is having to add a bunch of boost control after the initial boost spike to maintain 8psi with a 10psi wastegate. Running 60% duty on the EBCS doesn't make sense to see what we are seeing so we are both pointing our fingers at the recirc valve. I have a stable tune with overboost protection built in now, so the plan is to 1: add a vacuum distribution block and 2: install a new BOV in the charge pipe with a new MAF plate near the throttlebody. Then Ill go back and have Hal take another shot at it. :thumbup:

Debating now if I even need e85 with the numbers Im putting down.

Updated with a digital dyno sheet.

http://i.imgur.com/2lA3ZEH.jpg

Why would you want to run 8psi when you could run 10?

The 1980s called. They want their black and white scanner back.

Didn't say I wanted to run at 8. Looking at a BOVs right now to fix this mechanical issue Im having.

Looks like I will be buying this for my EFR recirc.

http://www.full-race.com/store/image...plates-1-0.jpg
https://res.cloudinary.com/rallyspor...s/tia_q_11bk_1

Whats your vacuum routing look like? Is everything t-ed off different things or do you have a vacuum block?

Its pretty jenky and might be the culprit. Will snap pictures tomorrow. I have a Treadstone vacuum block that is going on this weekend.

Updated my 1980's black and white dyno sheet scan on page 2

So 2015 that plot. Looks really good. I bet the car is tons of fun to drive and the boys at Dynosty are great.

Good that you got a result.

With the recirc valve, go to a scrap yard and get some brake line. Run that and just use rubber/silicone hose at the joins. If you can, also run the recirc line off the plenum on its own dedicated line.
It needs to have a stable and strong feed and if you have other things which bleed or pulse the boost/vacuum signal on that line, you may end up with problems.

EUREKA!

It was all in the junk OE recirc valve that was leaking/not engaging properly. Installed a new TurboSmart Plumb Back BOV. See photos below. @King Tut Im so happy right now! I did an EVAP delete, and routed the the under manifold vacuum port straight to the recirc valve. Boost comes on stronger, at earlier RPMs, and consistently.

I am recommending that anyone running an EFR with integrated BOV to upgrade to this little gizmo. It works splendidly.

Side note: I discovered some oil on the throttle body even though Im running a dual catch can setup :/ Ill have to do some digging there.

Thanks for everyone's help! Back to Dynosty for more fine tuning and ethanol!

Oil :/
http://i.imgur.com/EMEN0BV.jpg

Managed to do everything with just unbolting the TB. Didnt have to touch the AC comp.

http://i.imgur.com/mS0UhmS.jpg
http://i.imgur.com/rHau7GV.jpg

Reused the OEM rubber line coming off the bottom of the intake, clocked 180deg to account for the elbow. Used a barbed splice and some new 7/32" rubber vacuum line to get it to the BOV. Notice the blue zip tie at the barb. kinda hard to see.

http://i.imgur.com/DHhZm0c.jpg
http://i.imgur.com/4jnvUNg.jpg?1

See you later sucker.

http://i.imgur.com/RcuBpzt.jpg?1

No idea why that spring is rusting. I think its an indication of it not working right and leaking boost.

http://i.imgur.com/bMcAUST.jpg
http://i.imgur.com/u0E6msE.jpg

New parts! WOOOOO

http://i.imgur.com/v9XXUMS.jpg
http://i.imgur.com/jDLl10v.jpg
http://i.imgur.com/1GJx3Wy.jpg

Congrats. Is the new recirculation valve a rebuildable/tunable unit like a Forge or Tial is?

Sent from my SAMSUNG-SM-G870A using Tapatalk