no cel's, weak boost problem?? help??

[sublunacy]

i'm getting frustrated here, i read alot and post very little?
for the last year the boost level has been inconsistant.
i now have a mbc witch won't function with my current engine trouble.
no cel's , recently

new V-powers, Battery, Alt rebuilt, Silicone plug wires(age??),
knock sensor, 91 octane, mbc and guage, air and fuel filter,

my car used to run great, then fadded,
with mbc and guage getting good 4 psi boost upto maybe 4500 rpm
then fizzles and farts the rest of the way up.
checked obd-1 green and black codes for trouble nothing????
when i turn up the mbc(open) the spool and boost getts worse.

[subytech]

Did you compleatly leave out the stock solenoids when you plumbed in the MBC, one of them acts as a MAP sensor and still needs a pressure signal otherwise the car will run like crap. When I installed my MBC i just left all the vacuum lines in their stock places except for the signal line to the wastegate actuator (just removed it) and made the main signal line that normally comes from the compressor housing come from the vacuum line on the #1 intake runner (not ideal i know but it works)

[vrg3]

At 4500 RPM you should have more than 4 psi... so what could cause the boost level to be too low? Five things come to my mind:

Intake restriction -- Have you taken apart the intake tract to make sure there isn't somehow something in it? The air filter should make that impossible, but you may as well chcek.

Exhaust restriction -- Clogged catalytic converter, perhaps? Or muffler?

Boost leak -- Have you inspected the pipe from the turbo to the throttle body, as well as the blowoff valve, for leaks?

Bad turbo -- Does the turbo make a lot more noise than it used to, or does it smoke?

Bad wastegate actuator -- Do you have a source of low-pressure compressed air you could use to test the actuator?

[Arctic Assassian]

boost leak was another, but thanks vikash for enlightening me.

[Steeper]

is your MBC connected right?

hooking the wastegate straight to vaccume/boost should get you more than 4psi.


did you bypass the stock controler? mine was messing up and even with a MBC after the stocker it was making funny lack of power that I couldnt figure out.

try eliminating the MBC and just joing the vaccume line to the wastegate pot for now.

[vrg3]

It shouldn't be possible for boost controller issues to cause this problem, though. How could a bad MBC or bad hose hookups or whatever cause boost to be below the wastegate actuator's calibrated pressure?

[subytech]

When I tried trouble shooting my boost control solenoid problems I first tried running just wastegate pressure but i disconnected the vacuum lines going to the stock solenoids and the car spit and sputterd so much that even close to redline i wouldn't be making more than 5 PSI and I had my wastegate actuator signal hose comming straight from the manifold without any obstructions or "T"s inbetween

But you are right this almost sounds like an actuator problem not boost controller, week or failed diaphram? If you grab the rod going from the wategate actuator to the wastegate itself is it easy to move?

[sublunacy]

allright allright lets see here...

First off, Vrg3 It's great to have u here.I agree with your posts about
turbo backpressure, heat soak...

secondly my car sees cold winters, and frequent use.now at 320,000kms
It made sense for me to reinstall origanal pressure/boost controller,
so back to stock.
SO monday i'll get a digital a/f guage, I'm worried the Fuel Pump is tired out( unlikely??? lean= bad news FAST)

When I do get 5,6,maybe 7 psi(3500-4000+) it has less power and is very moody, not sure i can here the turbo spinning after 4 psi
basically 2500 to 4300rmp at 4psi=good
4400 + rpm = bad or 5+psi =bad


Finally.. mbc hookup was fine, the spool and power is not
-Something else comes to mind, my exhuast %#* smells!!or is it just me. I guess my cat could be clogged but the whole system looks in fine shape??
-Boost leak I will look into tmrw if its not super cold
-turbo does work and sound and smells ok i suppose...


if u guys can suggest more imperfections my sled thanks you
sssssssooo waste gate, Bov possibly pressure sensor bullshit.
if it is any of those 3 things Blackbart could be an option

[vrg3]

If you're misfiring a lot, you'd expect the exhaust to smell bad.

[BXSS]

I had a boost leak when I first installed the FMIC on the ej22t that was in my car & the symtoms sounded similar to yours + loud turbo spooling.

[Arctic Assassian]

Sometimes he doesn't hear the turbo...

[sublunacy]

Switched from high octane fuels recently, to 87 octane and i can feel major improvement. Engine runs Much crisper now!!!
Also today I cleaned up the grounds, noticable difference.
Between those two things. Engine runs runs like a new car again,
and very fast, untill 5000 rpm or BELOW 4PSI works OK
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WASTEGATE LEVER/ROD will Not move when i pull/push, hard as i
want with my hand(Hood removed) it is TOTALLY STUCK!!!
When i pump pressure into the Actuator (on turbo) it moves maybe
half an inch but at high pressure!!! around maybe 25psi(sorry i have shity pump and guage for that)

Also hear rattle coming from INSIde turbo aswell, that i thought was heat sheild, guess not.

What can I do about this ??? nothing simple right??

Replace turbo right?

Anyone have spare VF-11 in good shape???
Thanks EVERYONE for there 2 cents

[sublunacy]

bump

[vrg3]

It does sound like replacing the turbo is the way to go.

You could try other tests like disconnecting the wastegate actuator from the flapper to see which side is stuck if you want though.

I don't know what the rattle could be; turbos don't rattle. Can you be more descriptive?