low boost problem

[vortecfiero]

this is a real puzzle
I used to get 10lbs of boost at 2500 with out problem and it would go higher if i let it.
I have been running with it set @ 5 lbs while I mess with other non related stuff.
now i cant get more than 3 lbs at any rpm and it feels soooo slow

here is what i have checked

I have checked for leaks on the compressor to the throttle body ditto for cylinder heads to turbine section.
the turbo itself has no play in the shaft and the blades on both the wheels are fine.
I eliminated the BOV incase it was leaking.
I pulled the pressure line to the wastegate actuator to allow max boost (to test the actuator).
Locked the waste gate arm in a closed postion
i am not using a waste gate solinoid or anything else.
even if it was running on 5 cylinders id still have more boost

fuel pressure seems unchanged on my autometer guage
I will run data master to confirm the boost guage reading tonight.. but im not getting my hopes up

i remember playing with controlled leaks once to see what the leak to boost loss ratio was...
this would have to be a fair size leak and im sure i would hear an exhaust leak because
my car is quieter than a stock fiero V6 (full sleeper mode) except at full throttle

any ideas ?

 

[jwaller]

Re: low boost problem

please change your text to white. it's very hard to read when you have a blk background.

 

[jwaller]

Re: low boost problem

if you wired the WG shut and disconnected it then you have a leak in the intake "system" somewhere. where, it another question. You would hear an exhaust leak thus it's not that. so you have to believe that the turbo is recieveing enough air to drive the turbo to make the boost. so intake is where it's going. IC, hose conector, TB, intake leak. Do you still have good vacume at idle? if so then its not after the TB. so that kinda narrows it down for you.

 

[vortecfiero]

Re: low boost problem

please change your text to white. it's very hard to read when you have a blk background.

lol i use a grey background

 

[vortecfiero]

Re: low boost problem

if you wired the WG shut and disconnected it then you have a leak in the intake "system" somewhere. where, it another question. You would hear an exhaust leak thus it's not that. so you have to believe that the turbo is recieveing enough air to drive the turbo to make the boost. so intake is where it's going. IC, hose conector, TB, intake leak. Do you still have good vacume at idle? if so then its not after the TB. so that kinda narrows it down for you.

I have about 20 hg at idle and 15 to 10 at fast cruise
thanks for the ideas

 

[vortecfiero]

Re: low boost problem

god bless datamaster....
my check engine bulb must be burned out lol I forgot GM problems 101.. always check the bulb lol

I will address the 3 or 4 trouble codes and hopefully that will solve it.
I did a run tonight and it ran crappy before any boost....
Id put the file up but i have no way to host it... also with all the error codes
it might not tell too much

thanks anyways john....

 

[jwaller]

Re: low boost problem

good luck I hope that those codes once you get them fixed will fix your problems.

 

[midnightbluS10]

Re: low boost problem

Id put the file up but i have no way to host it... also with all the error codes
it might not tell too much

thanks anyways john....

Can you upload it to smaug's uploader as a zip file?

 

[vortecfiero]

Re: low boost problem

Its amazing how stuff just comes to you.
Ive been agonizing over a PROGRESSIVE lack of boost and an intermittent
code 42 which I thought was related. My check engine light was out.
thanks to data master I found the code 42 AND the system at 10 volts !

After after replacing the alternator and following the charts I found nothing...
then it all came to me.. I remembered Craig's 2nd rule of harness problems...
"its probably the connecter"
Sure enough it was the 4 wire connector to the dist. 2 of the wires were
not 100 % so i replaced it.

It ran like a dream soooooooooo smooth... but no boost and no pull after 3000 RPM
I just knew it was the catalytic converter...

I just wish this would happen at the beginning of the wrench'n session rather than
half snapped at a party and no one having a clue at my revelations.

Mrs Vortec: "oh dont mine him... Its a car guy thing..."

craig

 

[vortecfiero]

Re: low boost problem

just when you think you have a good thing going lol it gets better !!

My catalytic must have been partly plugged since day 1 of the turbo set up...
i had a problem with 4000 to 5000 range (engine will pull to 5500 no problem but the bbzb chip only allows 5000) I thought the turbine houseing may have been the culprit or perhaps
the compressor was too far into the nasty zone...

OMG it pulls !! I have to redial in my butt to keep my self out of trouble lol

 

[vortecfiero]

Re: low boost problem

ok now its getting silly.. 5lbs @ 2000 rpm.. and with a 5 lb waste gate im
getting 10lbs of boost at 4000 rpm... these are the problems i dreamed of lol
time for the external WG to get put on

to be continued...

 

[QUICK STORM]

Re: low boost problem

cool, glad to hear you got it figured out, i'm getting goosebumps reading your replies, makes me quite anxious to get mine running