I think GM included the sensors so they could charge the customer more. No one would pay $1000 for a retune.

 

you do NOT need the 3bar sensors...doesn't matter if you want trifecta or hptuners.....doesn't matter if you want 200hp or 2000hp....only reason to have the 3bar sensors is if you are tunning the gm stg1 upgrade....period.

for information regarding trifecta vs. hptuners vs. gms1 see my post in this thread (post #2)

https://www.chevyhhr.net/forums/show...569#post608569

 

Thanks for the clarification on my part. I'm used to playing with Fox Body Mustangs equipped with superchargers. This is my first turbo car.

 

hey no problem. it just gets confusing with someone coming in and saying yes you need the sensors and another saying no you don't. imo the stg1 kit should only be done if it will be your only mod and you are concerned about warranty....therer are so many issues that arise with the install later down the road that make it such a mistake for a lot of owners. the other options....trifecta and hptuners (can be) safer, offer much more power and reliability, and if you know what you are doing you can still obtain warranty work if needed.

my first turbo car too. a lot to learn but they're fun once you get it. good luck

 

From HPT Forum:

"I've gotten about 10 pm's in the last month with peeps asking the purpose of the 3 Bar MAP sensors on the LNF if you use a stock base file for the tune.

The short answer is "Because!" This is an FYI so feel free to add your input as you see fit.

First of all the stock sensors are 2.5 bar. 2.5 bar absolute is ~36.26 psi, now subtract 14.7 psi for 1 atmosphere and you are left with the ability to read and control boost up to ~21.56 psi.

3 Bar MAPs following the same example would be ~43.51 psi, subtract 1 ATM and you can measure and control to 28.81 psi boost.

I understand the ECU limitation for logging the manifold pressure is 255 kPa, or 2.55 Bar, this appears to be the same for the 2.5 or 3 bar sensors. We are left with this limitation in logging the mani boost.

The Lower Charge Pipe MAP is another story however. It is listed in the PID's as Boost Sensor LoRes (PID.2338.PSI) and appears to be capable of 512 kPa from what I have read. This gives us the ability to log and control boost pressure up to the limit of the sensor or ~28.81 psi boost.

While you can certainly boost over the 21.56 psi fooling the ECU with the stock sensors, it runs out of the control area, in other words, you are just telling it to shoot for the moon with no means of really controlling it.

The benefit of using the 3 Bar MAPs is expanding the control range."

Read on and decide for yourself.

http://www.hptuners.com/forum/showth...hlight=Bar+MAP

 

You beat me to it. 3 bar maps gives you better more accurate control over 21lbs of boost.

 

I guess I can leave the 3 BAR Map sensor in place when I go for my HP Tune. It did come with the car when I purchased it 2 weeks ago.

 

im sorry i should have been more clear. i was on my phone and wasnt paying that much attention to what the post was asking. the 3bar sensors will let the ecu see the higher boost levels correctly. what i was saying is they are not needed to achieve higher boost levels. the only way i would let those sensors touch my car is with the plug and play harnesses. i would rather have the ecu not be able to read the boost levels properly than have all the other bs issues that occur with the stage kit.

 

Id take the "shoot for the moon" boost option.

 

I am still having the problem with with the Hhr Ss. Have not done nothing yet with the problem of losing Turbo PSI because am waiting to get together all the info they have gave me here. I thank everybody for the info but just yesterday additional problem. I was riding my hhr yesterday stop on a traffic light and the vehicle just turn off, put it in parking and start it and it did right away. It did it like 2 times during the day and at that moment it was boosting OK. Yesterday the problem with the boost did it like 4 times and last it for a little while. After a while when I turn it on again it begin to boost ok. I'm taking it to the dealer on Friday but before will like to have more info now that is turning off when I stop. Does it have to do with the same problem it has with the turbo? Ask why it wasn't it doing it before ? Really don't know what to do. Hey to my expert on this forum please give a hand here so when I leave it to the Chevy shop give them an idea because they are really lost. They don't know what to do. They tell have call GM Performance guy and still trying to find out. I will appreciate your help guy. I like this vehicle so much but already having bad feeling and thinking of changing to thing that really don't want to do