Boost Leak Issues Continue - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Reply
 
 
 
LinkBack Thread Tools
Old 06-18-2015, 03:16 PM   #1
Junior Member
Thread Starter
 
Join Date: Jan 2015
Location: Saint Louis, MO
Posts: 164
Total Cats: 7
Default Boost Leak Issues Continue

Hey guys, I am having what I suspect to be a boost leak issue. At idle and under load, my boost gauge will read vacuum pressure from 20 to 0 when revving the motor. At idle and under load, my boost gauge will never read above 0, so I am not making any boost. (I know I won't make any boost at idle).

I have tried disconnecting my boost reference line from the compressor housing to the internal wastegate itself and running it under load like that, still nothing over 0. I also tried disconnecting the previous line^ as well as my BOV vac reference line and still nothing over 0 under load.

This almost makes me think that the wastegate could be the issue. It functions properly, though, because I connected my air compressor to it and it opened up at 7 PSI. Maybe the flapper door isn't seated all the way?? Could a slight exhaust leak where the exhaust housing sits on the manifold be the issue?

Any insight on the situation would be greatly appreciated. Here is a video for some visual reference to the situation...

'90 1.6 miata with DIYPNP, Greddy TD04H turbo, Kinugawa wastegate (7.35 psi spring), Greddy RS style BOV, Glowshift boost gauge, Hallman Pro manual boost controller (disconnected at the moment), RX7 460cc red top injectors, NGK 4644 spark plugs, Innovate MTX-L wideband
typicalsteve is offline   Reply With Quote
Old 06-18-2015, 03:31 PM   #2
Elite Member
iTrader: (17)
 
Join Date: Aug 2007
Location: Fort Myers, FL
Posts: 2,791
Total Cats: 130
Default

Assuming there's not a hole in your charge piping big enough to sick your fist in, there's another issue going on beyond a boost leak. "Boost leak" issues usually mean slower spool, you're getting nothing. Even with a 100% open wastegate you should still make a couple PSI so it's not the wastegate either.

I've never had a journal bearing turbo, but I think your turbo is the issue. When I shut my car off I can hear my turbo spinning down from idling for ~20 seconds. It looks like yours isn't even spinning at idle which seems very wrong to me, I feel like there should be enough exhaust passing it that it's spinning anytime the car is on. I wouldn't be surprised to see some serious shaftplay on your turbo and/or some good sized chunks missing from your exhaust wheel.

Also, you have to tune your VE map to tell the car how much fuel to squirt at any given MAP & RPM. The AFR Target table is what your car adjusts to when your tuning or in closed loop.

Last edited by pdexta; 06-18-2015 at 03:41 PM.
pdexta is offline   Reply With Quote
Old 06-18-2015, 03:37 PM   #3
Junior Member
Thread Starter
 
Join Date: Jan 2015
Location: Saint Louis, MO
Posts: 164
Total Cats: 7
Default

Ah, alright. I'll look into that then... I really hope that the turbo itself is not damaged. There's virtually no shaft play and I know it's getting oil. But I'll look into it
typicalsteve is offline   Reply With Quote
Old 06-18-2015, 03:46 PM   #4
mkturbo.com
iTrader: (24)
 
shuiend's Avatar
 
Join Date: May 2006
Location: Charleston SC
Posts: 13,780
Total Cats: 1,106
Default

Silicone intakes makes leak testers you could purchase and try. Here is a link to them.
shuiend is offline   Reply With Quote
Old 06-18-2015, 03:55 PM   #5
Elite Member
iTrader: (15)
 
patsmx5's Avatar
 
Join Date: Aug 2007
Location: Houston, TX
Posts: 8,797
Total Cats: 248
Default

Quote:
Originally Posted by pdexta View Post
Assuming there's not a hole in your charge piping big enough to sick your fist in, there's another issue going on beyond a boost leak. "Boost leak" issues usually mean slower spool, you're getting nothing. Even with a 100% open wastegate you should still make a couple PSI so it's not the wastegate either.

I've never had a journal bearing turbo, but I think your turbo is the issue. When I shut my car off I can hear my turbo spinning down from idling for ~20 seconds. It looks like yours isn't even spinning at idle which seems very wrong to me, I feel like there should be enough exhaust passing it that it's spinning anytime the car is on. I wouldn't be surprised to see some serious shaftplay on your turbo and/or some good sized chunks missing from your exhaust wheel.

Also, you have to tune your VE map to tell the car how much fuel to squirt at any given MAP & RPM. The AFR Target table is what your car adjusts to when your tuning or in closed loop.
I've had a journal bearing Garrett, and a BB EFR. Both would spin very fast at idle. You turbo STOPS?! That isn't right at all. Hell even when I killed the thrust bearing in the GT3271 from running it at choke flow, it still spun fine at idle.

OP- You got something going on with your turbo, start there.

Also do a boost leak check. And check all your hoses. Use a clamp or zip tie on every hose so they can't leak or pop off.
patsmx5 is offline   Reply With Quote
Old 06-18-2015, 04:57 PM   #6
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,370
Total Cats: 1,332
Default

Turbo should be spinning at idle, IMO. You have a big exhaust leak (unless you're running open downpipe, which is going to wreak havoc with your wideband readings at idle), and I think looking at the flapper door is a great place to start.

Rule out your IC pipes from turbo to throttle body by capping the air filter and the coupler at the TB, drill a hole in one of the PVC caps, hook up a Schrader valve, and pressurize the entire system to ~10psi (don't go higher or you'll blow a cap out).

I had a similar issue years and years ago, ended up wiring the WG "shut", but the flapper was caught on the downpipe and wasn't actually shut.
Savington is offline   Reply With Quote
Old 06-19-2015, 12:15 AM   #7
Senior Member
 
Join Date: Aug 2010
Location: Arl. Texas
Posts: 937
Total Cats: 23
Default

Oil restrictor used?
Melted cat?
Miater is offline   Reply With Quote
Old 06-19-2015, 02:20 AM   #8
Junior Member
Thread Starter
 
Join Date: Jan 2015
Location: Saint Louis, MO
Posts: 164
Total Cats: 7
Default

I took everything off and put it all back on today. Boosts safely up to 8 psi now!!
typicalsteve is offline   Reply With Quote
Old 06-19-2015, 11:15 AM   #9
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,899
Total Cats: 1,792
Default

Quote:
Originally Posted by Savington View Post
Turbo should be spinning at idle, IMO.
apparently you don't poverty turbo often.
Braineack is offline   Reply With Quote
Old 06-19-2015, 11:26 AM   #10
Junior Member
Thread Starter
 
Join Date: Jan 2015
Location: Saint Louis, MO
Posts: 164
Total Cats: 7
Default

Oh, FWIW, if anyone cares... It does spin very freely at idle now!
typicalsteve is offline   Reply With Quote
Old 06-19-2015, 11:44 AM   #11
Elite Member
iTrader: (17)
 
Join Date: Aug 2007
Location: Fort Myers, FL
Posts: 2,791
Total Cats: 130
Default

Great news. Any idea what the problem was or did you just take it apart and put it back together and it's fixed?
pdexta is offline   Reply With Quote
Old 06-19-2015, 11:49 AM   #12
Junior Member
Thread Starter
 
Join Date: Jan 2015
Location: Saint Louis, MO
Posts: 164
Total Cats: 7
Default

I'm not entirely sure but I'm fairly certain that I just didn't have the exhaust housing mated to the manifold tight enough... I bought some good locking nuts and those seemed to do the trick. I also made sure that my waste gate arm was holding the flapper door shut really tightly. Rookie mistakes... But there's a first time for everything I suppose.
typicalsteve is offline   Reply With Quote
Old 06-19-2015, 12:21 PM   #13
Elite Member
iTrader: (3)
 
concealer404's Avatar
 
Join Date: Aug 2011
Posts: 8,465
Total Cats: 783
Default

Quote:
Originally Posted by Braineack View Post
apparently you don't poverty turbo often.

My last $75 turbo wouldn't spin at all for about... the first 45 seconds of driving. Once it got a little heat in there it would break free and i'd get the spinny whistle noises.

Pretty awesome.
concealer404 is offline   Reply With Quote
Old 06-19-2015, 02:49 PM   #14
Junior Member
Thread Starter
 
Join Date: Jan 2015
Location: Saint Louis, MO
Posts: 164
Total Cats: 7
Default

If you have a journal bearing turbo and are not using an oil restrictor in the oil supply line, then that is actually normal-ish. It's called hydro-locking and it's fairly common when you don't run an oil restrictor in the line with journal bearing turbochargers.

But the spinny whistle noises are all that matter, right?
typicalsteve is offline   Reply With Quote
Old 06-20-2015, 12:04 PM   #15
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,370
Total Cats: 1,332
Default

Quote:
Originally Posted by Savington View Post
Turbo should be spinning at idle, IMO.
Quote:
Originally Posted by Braineack View Post
apparently you don't poverty turbo often.
Replace "often" with "ever"

Quote:
Originally Posted by typicalsteve View Post
Oh, FWIW, if anyone cares... It does spin very freely at idle now!
Savington is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 59 12-15-2017 09:00 PM
Moroso Air Oil Separator Catch Can Aroundcorner Miata parts for sale/trade 2 10-01-2015 04:20 PM
Going back to stock. Need some 1.6 parts. Trent WTB 2 10-01-2015 01:15 PM
Leaky Wilwoods mx592 Suspension, Brakes, Drivetrain 1 10-01-2015 01:45 AM
Bad head gasket or ? shooterschmidty Engine Performance 8 09-30-2015 11:28 PM


Tags
boost leak problem

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 02:42 AM.