Wastegate Opening To Early

[turbo2nr]

heres the problem, i have a 8psi spring in my wastegate and the car only makes 3-4psi with the wastegate connected. when the wastegate is disconnected it makes as much boost as i want it too, i only went up to 14psi at 4000rpms.

my setup. t4 , revhard, fmic, tial wastegate 38mm vent to atm, ssqv , ect.

at first i taught it was my wastegate that was bad so i bought this tial unit. and it still does the same think it only makes 3-4psi.

next i checked for boost leaks. i pressurized the i/c pips with compressed air to see if i would hear a hissing form a coupler and nothing . so that eliminates a hole in a coupler or lose coupler.

im stumped its not the wastegate, its not the i/c pipes or couplers and its not the turbo to the manifold or wastegate to manifold or else it would leak out exhaust and not spool up the turbo.

so what can it be?

[coolbone28]

Where are you getting your signal from for your WG?

[turbo2nr]

vac is coming right off the comp. housing of the turbo.

[frsh13]

If you are not using a boost controller you should only have one of the fittings in the wastegate. Try using a different vaccum source and see if that changes anything.

Edit: also double check to make sure you have the right spring, I know people who have gotten their Tials with the wrong spring in them

[turbo2nr]

i have both of the fitting on the wastegate im using the one on the bottom for a vac feed for the wastegate not the one on the hat. this is correct right?

also i took apart the wastegate and looked at the spring its the correct spring.

thanks

[frsh13]

Yea you are using the right fitting. Im pretty sure that you dont need the second fitting on top unless you are using a boost controller.

[scheffler]

Ok dude here is a tip get a manual boost controler (MBC). Set it to what you want in this case 8 psi. When that opens up it will automaticly open your WG beacuse your WG is openin at 3-4 psi. If you dont let it see pressure then it wont open.

Basicly you are blocking the air from geting to your WG untill you want it there. With this setup you could run a 8 psi spring and keep your WG closed as long as you want like 30 psi because your WG wont see pressure untill you let it.

[480sx]

So you boosted to 14 psi with your external wastegate disconnected, did you do that at low throttle?

Still however makes no sense that your wastegate would open at 3-4 psi with a 8 psi spring in, unless you have a huge pressure loss somewhere in your IC system. I mean since your wastegate vac line is coming from the compressor outlet, you should be hitting 5-7 psi of boost to your plenum.

Are you sure your boost gage is reading correctly? Id say the easiest and first thing you should do is swap out boost gages, and make sure your vac line running to it is good.

Did this problem happen just start happening all of the sudden or what?
Modified by 480sx at 8:42 PM 2/28/2008

[Florida240sx]

Your vaccum source for your wastegate should be comign form your intake mani. I use it from my FPR line 0 problems

[hotbox240]

Another idea is to run a JGS Vacuum Block inline with your brake booster line. Then run a nice large line from it to the wastegate. They work great.

[turbo2nr]

im running a vac. block but i dont think its a wastegate vac signal problem. ive been running this same spot for the wastegate signal and ive hit 8-9psi before.

im thinking more and more now i have a tear in a vac hose some where and its leaking out..

any idea on how to find something like that out?

[WDRacing]

Let me see if I understand this. You remove the vacuum line from the watsegate and it will not open therefore boosting until it pops. But if you hook the vac line up, it vents at 3-4 psi.

Do this, use a new vac line or atleast insure the current one is good. Then take a small drill bit and make a small hole in the vac line that goes to the wastegate. This will act like a manual boost controller by bleeding some of the pressure off. If the boost goes up, it's the spring pressure.

WD

[turbo2nr]

tnx wd i will get a new vac line and hook up my mbc again today. and i hope that solves it.

the car does seem to run a little rich.. back fires more then usuall

[Florida240sx]

You do the boost leak test yet. Tear somewhere in your couplers. I had a tear but it wouldn't "open" until after 10psi. So when I ran 8psi everything was fine. Hooked up a compressor and ran 60psi through my system and found my tear instantly.

[eazye2000]

i have both of the fitting on the wastegate im using the one on the bottom for a vac feed for the wastegate not the one on the hat.

I do believe you need to be using the the top most fitting. More towards the end, or 'hat' as you describe it. I'm not familiar with external gates, but I'm almost positive this is your problem.

If you are 'boosting' pressure into the lower chamber of the wastegate, you are, in essence, 'pressing' the gate open from under the diaphragm. Causing yourself to bleed(waste) boost at such a low pressure. You're helping the spring open the gate.

Try switching to the top, or 'hat' side of the diaphragm. That might help.. The only time you use the bottom, is with a boost controller or something.

Anyone else reading this, does this sound right? Or am I up too early and need to go back to sleep??

[WDRacing]

Go back to sleep, its supposed to be the lower one.

This is the vacuum port that should be used.

[turbo2nr]

wd you rock! lol yea i figured it was that one...

this damm problem is gona make me go crazy and break some thing or pull out my hair!!!

[PantherRacer]

Since this is about wastegates, How about someone explain What both the ports are for on the ext wg's?

[turbo2nr]

[spooled240]

that's a nice diagram

I run my vac source from the compressor housing fitting on the turbo and I have no problems. I have one question for you: How is your spool? Does it spool at .5 to 1 psi almost instantly? When I had boost leaks my boost gauge would just sit there at 0 for a while then it would build boost quicky at higher rpms.

[turbo2nr]

spooled240: actually it holds at 0psi for a while like a sec then it starts to climb the up.

well i connected the mbc today and turned it up. it first hits 8psi around 4300rpms and as i take it up to 6k it tapers off to 5psi.

im convinced its a boost leak.

it would make sense, b/c the spring in the wastegate is a 7.4psi spring and if its a 3psi drop or leak it would make the boost level around 4psi. and with out the mbc i was only making 3-4 psi. so therefore i have a 3psi leak some where in my system.

also the turbo is a little laggy to spool..

wow i miss boost i need to find this leak. its not any of my charge pipes..

[spooled240]

check vacuum lines on the intake mani. Did you disconnect the EGR? Try not to leave any unused vacuum ports left open, get some of those plugs at a local hardware store or something.

[WDRacing]

Run a new vac line to the wastegate. Use a source from the intake mani, I suggest the FPR regulator. Just use a"T" fitting. That way the wastegate will see what the manifold see.

[eazye2000]

Wow, I just read this, and didn't realize I had posted in here...

Read what I posted, and can't believe what I said.. I must have been thinking BOV or something.

[turbo2nr]

its cool eazye2000, haha it was late we forgive you...

im almost certain its an exhaust leak pre- turbo. i was on it today and i smelt alot of exhaust in the car and also a gass smell, it was strong like it made my eyes burn..

im using rtv gasket maker between my turbo and manifold as a gasket, im thinking it wore out or cracked, i need to go look into this and see.. that would explain a late spool and drop in boost pressure at high rpms..

[turbo2nr]

bump.. 6 month same problem.

changed: wastegatereplaced gasket and torqued down turbo to manifold so it doesnt leaktook off intake manifold, changed all gaskets and removed all emmissions.changed throttle body gasketchanged injectors o rings made sure all couples are super tightchecked bov for leak

and still only hitting 3-4 psi...

so i dont know anymore

[WDRacing]

My theory...

I've had some serious leaks before. One big enough to cause your car to only boost 3-4 psi would make it run so rich it would stall almost immediatly. So the wastegate is opening early. We just need to figure out why.

Have you checked the wastegate spring?

What vac source is gauge hooked to?

When you disconnect the vac line to the WG does it overboost?

Can you hear any exhaust leaks?

WD

[turbo2nr]

My theory...

I've had some serious leaks before. One big enough to cause your car to only boost 3-4 psi would make it run so rich it would stall almost immediatly. So the wastegate is opening early. We just need to figure out why.

Have you checked the wastegate spring?

What vac source is gauge hooked to?

When you disconnect the vac line to the WG does it overboost?

Can you hear any exhaust leaks?

WD

yes checked the wastegate and spring call tial, spoke with a tech, its a 7.6 spring.

the gauge is comming off a vac. block in line with the brake booster, i know its not making power b/c of my safc only hitting 88% @ wot as opposed to hitting 100% at 60% throttle on 8psi

when i disconnect the vac line comming to the wastegate i can hit 15+psi by 5k..

wastegate feed is directly form the turbo housing, and was able to hit 9psi.

i do not hear any boost leaks from the exhaust side.. so im stumped..

[WDRacing]

Have the gauge and wastegate run from the same source, test and let me know.

[turbo2nr]

ok will do that as soon as i get off work, if i change the wastegate feed to the vac block it will open later but ill still have a leak....

on the hiway it will hit 7psi and taper off to 4-5, around 5000rpms..