Boost problems after 20lbs

T

turbobuick1035

Member
Joined
Sep 6, 2003
Any ideas on what the problem could be? If I'm full throttle, car pulls great no break up..once I reach 20 lbs of boost, the car falls on it's face. If I let off the gas a little back to 17-18 lbs boost..car pulls strong again..already changed the 02 sensor since It's been many years and after the turbo seals went and blew all that oil through the exhaust. Any ideas what to check?
 
How is your car setup and tune that allows you to safely boost beyond 20#?
 
Well i can tell you the after i changed my pulleys from stock to the billet ones my boost jumped from 20 to 22lbs without me adjusting the rod and it pulled hard..I did get the turbo repaired from the seals going bad and blowing oil through the exhaust..i changed 02 sensor already..new plugs tomorrow
 
turbobuick1035 said:
Any ideas on what the problem could be? If I'm full throttle, car pulls great no break up..once I reach 20 lbs of boost, the car falls on it's face. If I let off the gas a little back to 17-18 lbs boost..car pulls strong again..already changed the 02 sensor since It's been many years and after the turbo seals went and blew all that oil through the exhaust. Any ideas what to check?
Click to expand...

You should list ALL your mods in your sig,that way peeps can give you more informed replies ,as they will know more about what you are dealing with.
Do you have alky inj, running e-85 or just pump gas ?
Do you have a scanmaster or any other way of monitoring your data, knock ,etc.
Info, info,and more info will help get you better answers.
 
Last edited:
Not trying to scare ya...

But I had the exact same thing. Pulls strong at 3/4 throttle (10-15 lbs of boost), but full throttle (17-20 lbs) is would 'fall on it's face', not pulling as hard as 3/4 throttle. My issue was a very worn out engine. After blowing another set of head gaskets, I tore down my engine. I found, among other things, my cylinder walls were very worn. Piston to cylinder walls were waaaaaay out of spec (don't remember the measurement right now).

This was causing a lot of blow by in the combustion chambers, allowing the combustion gasses to pass through the piston rings and into the engine.

hopefully it is something else like fueling or something. Create a signature of your mods.

Good luck
 
t-typinator said:
You should list ALL your mods in your sig,that way peeps can give you more informed replies ,as they will know more about what you are dealing with.
Do you have alky inj, running e-85 or just pump gas ?
Do you have a scanmaster or any other way of monitoring your data, knock ,etc.
Info, info,and more info will help get you better answers.
Hopefully that break up you are talking about after 20 lbs of boost is not severe detonation.
Good luck.
Click to expand...
Alky, have scan master...there is no detonation at all.
 
Running strong zero problems before I took turbo off for repairs..got turbo back everything fine except for this issue after 20lbs
 
No...engine was rebuilt in 2003.. Never ran it more than 20lbs all these years..I don't think all of a sudden I need a rebuild.
 
turbobuick1035 said:
Any ideas on what the problem could be? If I'm full throttle, car pulls great no break up..once I reach 20 lbs of boost, the car falls on it's face. If I let off the gas a little back to 17-18 lbs boost..car pulls strong again..already changed the 02 sensor since It's been many years and after the turbo seals went and blew all that oil through the exhaust. Any ideas what to check?
Click to expand...
In my experience, "breaking up" is cured by installing an AC Delco module and coil pack. "Falling on its face" is cured by replacing the fuel pump. You mention both symptoms. Which one do you have?
 
It could be a multitude of fuel or spark issues, or it could be as simple as the wastegate blowing open?

Data or information from a Powerlogger would a good starting point.
 
GNRick said:
In my experience, "breaking up" is cured by installing an AC Delco module and coil pack. "Falling on its face" is cured by replacing the fuel pump. You mention both symptoms. Which one do you have?
Click to expand...
I put there is no break up, none what so ever when this is occurring
 
^^^ Ok, since you say there's "no break up", check the fuel psi,...
14 y/o valve springs don't help.
 
Chuck Leeper said:
^^^ Ok, since you say there's "no break up", check the fuel psi,...
14 y/o valve springs don't help.
Click to expand...
Its just wierd how all of a sudden this happened after the turbo repair when i was hitting 22lbs with no issues..acuator maybe finally went and cant hold it anylonger..I did mess with it meaning adjusted it to get higher boost after it hasnt been messed with in years. Maybe it cant hold more than 20lbs anymore
 
turbobuick1035 said:
Its just wierd how all of a sudden this happened after the turbo repair when i was hitting 22lbs with no issues..acuator maybe finally went and cant hold it anylonger..I did mess with it meaning adjusted it to get higher boost after it hasnt been messed with in years. Maybe it cant hold more than 20lbs anymore
Click to expand...

With alky you should be able to run well in excess of 20 # boost. I run 21 with no alky.


Sent from my iPhone using Tapatalk
 
When you reach the 20psi, and the car falls flat, does the boost drop off simultaneously? May be the actuator or a vac hose collapsing possibly?
 
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