katriik

Hello everyone.
So I decided to try a WOT at third and fourth gear to check the current pressure I can get from a recently purchased Cobalt SS 2010.
The MAP sensor got stable at 249 kpa (34.8 PSI) several times.
I realized that the MAP sensor is the one found with GM stage 1 option.
I would like to check with you if that is a normal value or if I need to further investigate if the previous owner did other things to the engine.
Thanks a lot.

blueLNFftw

iTrader: (16)

You are likely not logging correctly and that really means you are running a 20psi tune.

katriik

So when I read the pressures on the forum, they are boost only, not map, correct? Because the boost gauge on the car shows 140 kpa (as you said: 20 psi).

ECaulk

iTrader: (6)

If you're reading off the MAP sensor in hptuners, you have the wrong sensor and it will peg at 249kPa. You need to log the lo res map, which is the sensor in the charge pipe. Again both are absolute pressure not a gauge pressure above atmosphere so the baro reading needs to be subtracted to get to boost

katriik

The reading is from Torque-BHP... Android app, very basic. I am new to this world so I'm trying to learn everything I can.
I saw there are two pressure sensors on the car, one fixed on the manifold intake and the other from the charge pipe. The app says Intake Manifold Pressure.
Any ideas on how to be sure? Just by disconnecting?

blueLNFftw

iTrader: (16)

I don't know anything about those apps to help.

Sorry.

Just subtract 14.7 and you have your reading.


Your boost gauge is accurate though. It's probably a GMS1 factory tune.

ECaulk

iTrader: (6)

I know nothing about that app. I'd put anything that logs pressure and see the differences and compare to the gauge

tomj77

iTrader: (2)

34.8-14.4 = 20.4. Ur running 20 psi

ECaulk

iTrader: (6)

Two points, first I incorrectly stated that the map pegs at 249kpa when it's actually 255kpa.

Also 249kpa is actually 36.1psi. So OP's actually running a 22psi tune, and needs to log the charge pipe map

califcarm

I am almost 100% sure the app is reading the intake manifold sensor. My app was (app that comes with OBDlink MX). Which is capped at 255kpa as was previuosly stated (22.5 psi gauge). Even with the GMS1 3 bar sensors in place, the PCM will only report a max value of 255kpa (even though the sensor goes much higher).

You seam to be just under that, so it is probably reading correctly. But beware that if the app boost flatlines at 255kpa, it could be higher in reality.

HP tuners is by default just going to read that same sensor that has a PCM cap of 255 (intake manifold sensor). You have to setup a PID for Boostlo-res which is not capped by the PCM and will read and report up to the max of the sensor itself (3 bar if you have the GMS1 sensors).