foxtrotraptor

But doesnt the PSI varies on altitude?

Motorbreath

Theoretically you should see about 2-3 more psi than I do at your elevation. I'm at 6500'.

firemangeorge

Fwiw. I see 19-20 on mine with the GMTU at sea level here. It was 14 when it was stock.
I have seen 310lbs torque on the RPD, so my output seems correct with these boost numbers.
Too many folks seem to worry about the boost numbers when it is the hp and torque increase you get that is the key. Remember that the torque management system should limit the boost when it reaches the peak power output.

bigjacksauto

I checked with one of the best tuners (james) about the issue of it not boosting properly when you are cruising along.
James thought it was probably the Gmtune seeing torque and therefore it would not make the proper amount of Torque.
I am pretty positive after looking into this over and over that its clearly the way the tune is designed. I have an email some where from one of the original engineers on this project and the gm tune only adds power during a certain rpm another words it will add power from say 2000-5500 rpm then it will drop back.
I have a dyno sheet that shows this .Anyhow back to the issue where you are driving along at 60 and floor it and it boosts to 15 and then you go back to 60 and then floor it after letting the motor see more than 10" of vaccum I believe is the way the tune is written.
If it was an electrical issue it would not do this consistentley
I would love to be able to drive along say next to an import and then hit it and know it will boost what it should instead of having to let off then give it gas
I reall hope they revisit this issue and fix it in its tune.
Looking back on this issue and as much as it kills me to admit this I think I would have dropped the warranty and tuned it myself instead of putting the money into the Gmtune
or at least had someone hptune it.
Very disspointing to spend 700 plus dollars and have it feel like a dud at times.
I have talked to tom at CED about this over and over and even more_hp_more_torque.


Here is the dyno sheet I believe that I originally received from More hp more torque
this makes a lot of sense as to what we are seeing even though its from a cobalt ss
note that around 5500 rpm the power almost goes back to the power of what a stock ss would make and it appears to do this by backing the boost down in this area

foxtrotraptor

I agree. Just last night I smoked a Mazda Speed3. No way I would have been able to do that with my Automatic if the GMTU didn't work right.

bigjacksauto

A speed3
Was that from a roll
More details please.
I small sure the speed3 was not happy

2005HHRauto

I bet that this is one of the tables, in question, that works, hand-in-hand,
with a few other tables.
Max Air Load Torque table - Torque used to calculate the maximum allowed air load.

Stock HHR SS table above

GMMP table above

HPTuners – table changed, to how my automatic likes it, for street & strip

2005HHRauto

This is why Stock HHR SS automatics, suck...
GM limits you to only 63-79% of power, in 1st & 2nd...
You don't get full power, until 3rd gear...

Stock – Maximum torque , RPM vs Gear, above

GMMP – Maximum torque , RPM vs Gear, above

foxtrotraptor

Yup a speed3 :). Probably a 07 or 08 model. Yeah from a roll we were going maybe 30 35mph. Had to avoid some traffic for a few seconds before we both had open lanes. He had a custom exhaust it was loud so i know was gunning it, but he never caught up I was seeing 20 or 21 psi at the time. The drive seemed very surprised, probably had never even seen a HHR SS until then, once we got to a red light he was in the lane next to me but he hung back to check out my car.

bigjacksauto

2005hhrauto thanks for the charts
lots of info info in there

fox did you start off from a light holding it in 1st then hit it or did you just have it in d and floored it.
20 plus psi of boost on these things and its tough to catch them