Alright so lm loosing boost over 5000rpm, it drops to around 80kpa(like 11psi)
lm running a 2.8 WITH 60's no other mods... l brought it to the dealer to see if the anything was broken but nothing was found!!! So some idea's are welcome

Thanks Jay

 

belt slip

 

https://www.cobaltss.net/forums/how-guide-43/how-boost-bypass-mod-11994/

 

I can almost guarantee if you do boost bypass mod that will take care of it. Your pcm is more than likely bleeding your boost because it's getting hot. mine did the exact same thing.

 

what is a boost bypass mod ?

 

belt slip...would that mean my belt tensioner is going?? cause that seems to be ok...

too hot..so l purchased a dual pass endplate from a fellow member, will that solve this problem??

 

Stage 2 belt or stock?

 

yes that end plate will help ALOT! But you would still wanna do the boost bypass so your pcm doesn't limit how much boost the supercharger can make. Just be careful with it. You should be fine with a dual pass and a 2.8. look it up its a 5 minute mod. Helped me tremendously.

 

Sometimes when this happens it means your intercooler pump is shot. When IAT2 temps are too high your car cuts boost to around 10psi.

 

Yeah thats what everybody told me but mine was fine. Check it and if its ok then do the bbp mod. If you can't hear your belt slipping it's probably not that.

 

Either the IAT2 is getting too hot and it is pulling boost or the more likely answer is that the torque management is kicking in and reducing boost.

 

l have a stock belt with a larger tensioner pulley...my iat2 are at 90-95 yesterday at the track... l really don't want to do that bypass, enless its just at the track

 

The boost bypass will work, but you will get crappy gas mileage if you leave it all the time.

Your IAT2 are great, I am sure the problem is that the car is limiting boost because of torque management. You will need to get a tune to have your torque management settings removed if you want to see full boost.

 

rnjmur, have you seen his iat2 temps with a scanner? just curious how you know they are fine.

belt slip would only cause a momentary drop in boost. Your ecu is probably cutting boost due to high iat2 temps.

since you have a 2.8" pulley with no other cooling or exhaust mods, it is likely that the iat2 is high. In this case you DO NOT want to disable the bypass solenoid. It cuts boost at a certain IAT for a reason. you will damage your engine if you continue to push full boost at these iat2 temps.

doing the boost bypass valve mod will not effect your gas mileage. the bypass valve will still open normally when you are under light throttle and vacuum is present.

Sheesh.

 

l have a tune..we worked on the tune for a few hours tryin to fix this boost issue..lm thinking now l just going to install the dual pass and opt b tank and see if that solves the prob or REALLY helps
Thanks for all the post

 

He posted that his IAT2 were at 90 when at the track. Of course that is not during a pull, but with IAT2 at around 90 you should be able to do one pull for sure without it pulling boost because of IAT2 being high. The IAT2 has to go above 200F before it pulls boost.



You really shouldn't be running a 2.8 without at least a bigger H/E or the dual pass (should have both really). It could be possible that the boost bypass itself is bad, but I am still going to bet that problem is somewhere in the tune. You probably still have torque management enabled somewhere, I have seen this happen many times.

 

Have you checked to see if the pump is working? Simply pull the IC res. cap when the car is running and you should see flow left to right.

 

my dual pass is comin tomorrow, l wasn't planning on running the car like this for long. I just had the 2.8 installed like 2 weeks ago

 

From reading on here, IAT2's should be +20 to +30 of ambient temperature. At 90-95 degrees this is probably within the required temp and doesn't have anything to do with your issue.

 

l think its the boost solenoid, l do the boost bypass mod and it holds the boost...

 

I would replace the solenoid and see if that fixes it. If it does, then that was the problem. If you still have the problem after you replace it then the problem is still in the tune somewhere.

 

I did the boost bypass mod i think. I took the hose coming from the boost solonoid off the regulator, and left the hose that comes off of super charger to acuatior on. My iats are still 20-30 = ambiaent. And i boost to a complete 18.5 with a ported blower. 2.6 pulley, heat echanger, an nd no other cooling mods. lol

 

And think your right,i think its the torque mangement is on... Im going to go see my tuner, if not im going to be looking for a tuner come spring

 

mine did the same thing even with the torque mangement off it was the bypass solenoid

 

That was my other thought...where did you pick up your solenoid? at the dealer?