I have an 05 ss/sc with 60# injectors, ottp he, 2.7 pulley, pacesetter header, zzp catless 3" dp and zzp 3" full exhaust. All tuned on HP Tuners. Was boosting around 18lbs now wont go above 12lbs. I have an aeroforce gauge and manual boost gauge reading the same. Need to know where my problem is. Any help is greatly appreciated.

 

Did the boost change after any of those mods or just randomly

 

I just noticed it randomly one afternoon then started to take curiosity into the situation because I knew it wasn't right

 

With my understanding of lsj's being limited I believe when you "open up" the exhuast you will increase airflow but lose psi
How much im not sure was it boosting 18 after all your exhuast mods?

 

12 is low on a 2.7, look for vac leaks. What is ur vac at idle ?

 

Yes it was for a while until it started leaking. I've checked all my vacuum lines and no leaks

 

Vac at idle is -19 on my aeroforce. -16 on my manual gauge

 

Possible blower gasket leak.

 

i think if he had a blower gasket leak he would be making more boost instead of less..


OP did you noticed a loss in power?

 

Yes I did thats why I started to really pay attention to it

 

you could try doing the boost bypass mod to see if the bypass valve is opening to limit the boost. if you do the mod and you build your usual boost pressure then you know the bypass valve is opening. i wouldnt continue to run it like that tho because there must be a reason for it to be opening.

 

Sounds like the bypass is failing.

 

Ok. Ive tried to look the mod up multiple times but the pics never load for me. So in turn I dont actually know how to do the mod. Could you help so I could see if its the bypass

 

https://www.cobaltss.net/forums/how-...ass-mod-11994/

 

you disconect that vacuum hose from the boost actuator thing, then plug that hose with a screw. you leave the actuator open into the atmosphere.

 

With the mod pulled to 15lbs. Nothing higher

 

Did you push on the valve arm to make sure its fully closed? It's probably still partially stuck open.

 

Are you talking about the actuator on the supercharger?

 

yea it looks like a canister on the blower, make sure the metal plate is closed all the way, that plate could be getting sticky and not closing all the way.

 

So pushed in the actuator not extended out

 

Boost bypass mod *Free mod* | ZZP News

give this a try

 

This same problem is happening to me used to get 16lbs but now randomly wont go past 12lbs. Op did you figure out what it was?

 

Never figured it out. I did all the mods and still nothing. Im assuming since my tensioner is roaring like a bad wheel bearing that is probably causing my issue. Or at least hoping its my issue

 

I did the zzp bypass mod and now its hitting full boost, turns out my bypass wasn't closing all the way.