1jz wont boost past 10psi, possible turbo failure soon?

**77GZE** · 30-01-2009, 10:12 PM

hey guys, as you know the ra28 i have gets a flogging,
and only recently the boost has slowly dropped.
Now, it just had 3" dumps and always ran right up to boost cut, without a boost controller
Slowly its dropped and only gets up to 10psi now
i have checked everywhere for leaks and i assume this leaves me with only 2 things
wastegate playing up,
or 1 turbo is gonna flick a blade or 3 soon...
which id rather avoid, has anyone else had this problem before a turbo goes???
has anyone had wastegates play up?
Steve

**web** · 30-01-2009, 11:48 PM

Already checked the obvious ? ( clamps and leaks and such )

**77GZE** · 31-01-2009, 04:29 AM

yeh man, several times.

**PlacentaJuan** · 31-01-2009, 04:45 AM

i would not have thought that a turbo would show any signs of immnent failure like that (low boost)

i mean its either broken or its not, even 1 millisecond befoer any blades actually let go, it is still working.

also have seen plenty iof pics of aftermarket turbos with large pieces missing from the blades that still seemed to work perfectly.

either way, if you think the turbo is broken, then pull your dumps off and have a look at your cat; any turbine pieces should be caught there.

**broken22** · 31-01-2009, 08:23 AM

My 200SX has started doing the same thing, the following possibilites have occured to me.

1) faulty wastegate or wastegate seized slightly open
2) cracked exhaust housing around wastegate
3) dead catalytic converter
4) dud turbo-manifold gasket (thought I would hear that though)

First thing I am going to try is dropping the exhaust off after the dump pipe.

**Dieseltrain** · 31-01-2009, 09:25 AM

I reckon Blocked Cat ... Or Vac line leaking somewhere... Check the Cat 1st as these are prone to give what you describe.

**77GZE** · 31-01-2009, 12:12 PM

ill go rip the cat off,
as when the car is cold, it will boost slightly higher!
about 12-13psi
but the cat is only 6 months old

**love ke70** · 31-01-2009, 02:41 PM

drop the exhaust and try.
if that doesnt fix your problem drop the dumps and check your wastegates.

when i launched a ceramic turbine wheel into my muffler, it was spooling up just fine, and then i hear a tink tink tink, and it all goes dead. so no, i dont think you would notice any loss of boost until you send things into orbit...

**SillyCarS** · 31-01-2009, 03:00 PM

+rep for floggin the shit outa 1j!

**thechuckster** · 01-02-2009, 12:59 AM

i know it's impossible for the rear turbo, so pull the inlet off the front turbo and check turbine shaft for play.

failing turbo bearing might be a cause ... but seeing as you give the car a flogging, perhaps wastegates are a more likely culprit.

Look at the upside ... a big single upgrade might be sooner than you think

**77GZE** · 01-02-2009, 03:55 AM

i dont want a big single i like the twins

i got 3 spare sets of good twins

**Officer Doofy** · 01-02-2009, 11:44 AM

Blocked filter or cat. Its not unknown to kill a cat in six months with an overly rich tune. Pull it off for a check. Pretty easy to remove the heatshield and check the acuator arms too, but you would notice different spool times to normal if they were stuck open.

**love ke70** · 01-02-2009, 12:05 PM

you also notice an increase in lag if you are getting excessive shaft play, i sure did anyway, went through 3 out of 5 turbos that way

**Mr DOHC** · 01-02-2009, 02:23 PM

what about a leaking BOV

**77GZE** · 01-02-2009, 03:10 PM

yeh im concidering that, is a GFB stealth one...
maybe no calibrated right?

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