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In desperate need of help to resolve boost issue.

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Old Jan 22, 2015 | 10:56 AM
  #21  
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Originally Posted by stevieturbo
There may be no way to adjust, but that still doesnt mean it is doing what you want, what you expect, or what you think.

Hence confirming it isnt doing anything strange.

I highly doubt the problem is some leaky exhaust valves as that wouldnt explain the w/g opening at 0psi
What I meant was I don't have a way to verify timing. I will call the dealer to see if they have a way to tell what the timing is doing. If the valves are leaking I would get combustion in my exhaust which could cause the wastegate to open and also cause my exhaust to be glowing red hot 30 seconds after start up?? I'm really grasping for straws here as I've changed everything trying to resolve this issue.
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Old Jan 22, 2015 | 11:12 AM
  #22  
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Originally Posted by chiaj144
What I meant was I don't have a way to verify timing. I will call the dealer to see if they have a way to tell what the timing is doing. If the valves are leaking I would get combustion in my exhaust which could cause the wastegate to open and also cause my exhaust to be glowing red hot 30 seconds after start up?? I'm really grasping for straws here as I've changed everything trying to resolve this issue.

Combustion could only ever open the gate if pressure inside was high enough to do it. And if that was the case the turbo would also be spooling and creating boost.

But as you say the gate is opening at 0psi boost...that makes no sense.

Yes a leaky exhaust valve could cause the glowing, as could retarded timing, incorrect valve timing, excessively lean mixtures etc.

You need to find a way to either make a TDC pointer and use a timing light which is the best option ( although guessing a difficult one )

Or at least interrogate the ecu to see what timing it is claiming to give ( but this may not be actual )

Did you try as I asked some time ago about trying it with no hoses connected to the w/g at all ?
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Old Jan 22, 2015 | 11:57 AM
  #23  
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Originally Posted by stevieturbo
Combustion could only ever open the gate if pressure inside was high enough to do it. And if that was the case the turbo would also be spooling and creating boost.

But as you say the gate is opening at 0psi boost...that makes no sense.

Yes a leaky exhaust valve could cause the glowing, as could retarded timing, incorrect valve timing, excessively lean mixtures etc.

You need to find a way to either make a TDC pointer and use a timing light which is the best option ( although guessing a difficult one )

Or at least interrogate the ecu to see what timing it is claiming to give ( but this may not be actual )

Did you try as I asked some time ago about trying it with no hoses connected to the w/g at all ?
The turbo will make boost, way too soon and way too fast if I unhook the reference line or hook it up to the top port of the gate. I can make 15lbs at 10% throttle like that. I can spool the turbo on the jack stand with no load. When the gate opens it doesn't sound like it's fully open, sounds more like it's fluttering open and closed.
I spoke to the dealer and he said only way to verify timing is through the ECU with their computer system.
I have video that I will try to post when I get home.
Thanks for all the tips, Carl.
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Old Jan 22, 2015 | 12:08 PM
  #24  
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Presumably as a fairly modern fuel injected engine, it has some form of EOBD connectivity ?

Again your symptoms sound more like heavily retarded timing, or a exhaust valve related problem...but more valve timing than just poor sealing valves. They'd need to be diabolically poor..
And if they were that poor in the first place you'd have little compression and it would run bad all the time.

Compression test ?

So back to the "history" question.

When did it last run normally...or has it ever ran normally ? Or what work has been done to the engine itself ?

And how are you actually trying to tune this ?
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Old Jan 22, 2015 | 12:22 PM
  #25  
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Sounds like the turbine housing is way to small for the engine. That would cause enough backpressure to open even a 15lb gate, and cause the exhaust to glow, and cause ultra quick spooling. Is the exhaust side the same size as others have run on that sled?
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Old Jan 22, 2015 | 02:24 PM
  #26  
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Originally Posted by vinnysnova
Sounds like the turbine housing is way to small for the engine. That would cause enough backpressure to open even a 15lb gate, and cause the exhaust to glow, and cause ultra quick spooling. Is the exhaust side the same size as others have run on that sled?
My buddy has the same setup same turbo and housing just different fuel system and smaller down pipe.
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Old Jan 22, 2015 | 02:29 PM
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Originally Posted by stevieturbo
Presumably as a fairly modern fuel injected engine, it has some form of EOBD connectivity ?

Again your symptoms sound more like heavily retarded timing, or a exhaust valve related problem...but more valve timing than just poor sealing valves. They'd need to be diabolically poor..
And if they were that poor in the first place you'd have little compression and it would run bad all the time.

Compression test ?

So back to the "history" question.

When did it last run normally...or has it ever ran normally ? Or what work has been done to the engine itself ?

And how are you actually trying to tune this ?
Yes it can be hooked up to the dealers computer to verify timing.

I haven't done a compression test just a leak down test.

Sled ran great last year. Machine shop had the head off to put a head shim in and set the valves. It hasn't worked right since then.
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Old Jan 23, 2015 | 04:37 AM
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So no other changes were made from before and now ?

Just that head shim ? ( What's a head shim ? lol )
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Old Jan 23, 2015 | 09:00 AM
  #29  
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So I found the timing chain guide had fallen down into the block putting tension on the wrong side of the chain which caused the cams to be retarded.
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Old Jan 23, 2015 | 11:54 AM
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Good find
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Old Jan 23, 2015 | 08:34 PM
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Originally Posted by chiaj144
So I found the timing chain guide had fallen down into the block putting tension on the wrong side of the chain which caused the cams to be retarded.
Is it running good now? I wanna see some vids of a turbo sled!
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Old Jan 23, 2015 | 09:02 PM
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Originally Posted by 66Chevellelq4
Is it running good now? I wanna see some vids of a turbo sled!
Me too. Hurry up before our nice snow goes away. LOL.
Hopefully this is the fix. SOunds like it to me.
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Old Jan 24, 2015 | 07:54 PM
  #33  
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Same problems. Fixing the tensioner did nothing to solve my problem.
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Old Jan 25, 2015 | 03:22 AM
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Go back over what Ive said then, back to basics.
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Old Jan 25, 2015 | 01:52 PM
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. Funny thing is if I unhook the reference line to the gate it will pull hard as soon as boost comes on until I decide to let off to prevent over boost.[/QUOTE]

I would say this is the area to examine more since power is there except when boost fails.
Also, is your map sensor after the t.b.?
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Old Jan 25, 2015 | 11:43 PM
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So I unhooked the piggy back fuel system and ran it on the stock injectors. I ride it for 30 seconds and the exhaust manifold is cherry red. Going to test it with stock pipe and muffler tomorrow to see if it's the turbo causing the restriction.
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Old Jan 26, 2015 | 01:18 AM
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Just open the wastegate.
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Old Mar 31, 2015 | 08:27 PM
  #38  
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Wanted to follow up on this. Tested back pressure and I had over 12lbs at 0lbs. 20ish at a few lbs of boost. Got rid of the Tial housing and it's pretty much 1:1 now and pulls hard.
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Old Mar 31, 2015 | 10:51 PM
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Originally Posted by chiaj144
Wanted to follow up on this. Tested back pressure and I had over 12lbs at 0lbs. 20ish at a few lbs of boost. Got rid of the Tial housing and it's pretty much 1:1 now and pulls hard.
Glad it's resolved, but why in the hell was this not a problem BEFORE the head shim? (still no idea what that is, lol). Did you have a different housing prior to the head shim?
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Old Apr 1, 2015 | 04:43 AM
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Dont know if im missing something here....You removed the tial wastegate? Replaced it with another i presume?
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