Question about boost
Question about boost
Ok, I have the RPD.
At idle, I have 0 boost
When I floor it, it maintains around 9-12 lbs and spikes at 15-16 for about a second every gear
Is this normal?
Also, if I have the car in park, and rev my engine, it doesn't boost. I can hear the turbo, but the RPD won't give a reading. Is that normal as well?
Sorry for the noob questions, I'm still trying to figure these things out.
At idle, I have 0 boost
When I floor it, it maintains around 9-12 lbs and spikes at 15-16 for about a second every gear
Is this normal?
Also, if I have the car in park, and rev my engine, it doesn't boost. I can hear the turbo, but the RPD won't give a reading. Is that normal as well?
Sorry for the noob questions, I'm still trying to figure these things out.
Ok, I have the RPD.
At idle, I have 0 boost
When I floor it, it maintains around 9-12 lbs and spikes at 15-16 for about a second every gear
Is this normal?
Also, if I have the car in park, and rev my engine, it doesn't boost. I can hear the turbo, but the RPD won't give a reading. Is that normal as well?
Sorry for the noob questions, I'm still trying to figure these things out.
At idle, I have 0 boost
When I floor it, it maintains around 9-12 lbs and spikes at 15-16 for about a second every gear
Is this normal?
Also, if I have the car in park, and rev my engine, it doesn't boost. I can hear the turbo, but the RPD won't give a reading. Is that normal as well?
Sorry for the noob questions, I'm still trying to figure these things out.
en.wikipedia.org/wiki/Turbocharger
The second part is normal - no boost if no load on engine.
The first part seems off to me, but I have one of them "shift-it-yerself" shifters. I can hit and hold 15-ish on mine. I don't know why it would drop like that, even with a slushbox.
The first part seems off to me, but I have one of them "shift-it-yerself" shifters. I can hit and hold 15-ish on mine. I don't know why it would drop like that, even with a slushbox.
That's how my Auto was before the tune. I would regularly get 12 steady and spike to 15 briefly in the later gears. I know atmosphere and your climate and all can effect the numbers.
Its very warm and humid down here and Mine always seem to be a little lower than the norm
Its very warm and humid down here and Mine always seem to be a little lower than the norm
I'm wondering if it just doesn't register with the transmission in park? I dunno. I can certainly hear the whine when in park and revving.
Know a little bit about turbo systems, but not the HHR SS specific system. It would seem to me if RPMs are increased, turbo will spool up, but with no load, could the waste gate be triggered to open to dump any unneeded boost? just rambling ,sure i'll be corrected by some more knowledgeable folks if i'm wrong ...
Correct...
Our ECM is torque based…
Torque is delivered, based on the "Desired-Air-Load" table…
If you have an automatic HHR SS, with the stock "tune", you are being
restricted in so may ways, as GM really went to far, in limiting torque,
in order to prevent warranty issues, with the automatic.
These two tables, show how the stock program, bites, big time:
The 1st table shows torque being limited, in all but 3rd gear !!!!
The table gear headings, show an HPTuner error, should be 1,2,3,4,5 instead of 1,2,4,5,6, so where you see 100%, on the table, it is really 3rd gear, not 4th. Just a small typo error by HPTuner...
Most all "tunes", even the GMPP turbo upgrade "tune" have 100% power in 1st, 2nd, 3rd & 4th gears, with automatics...
You only get FULL power, in 3th gear, with the stock automatic HHR SS...

This table below, is the really ****ty automatic power curve, so bad, really, really, bad...

This table below, is a typical power curve, when "tuned"…

So, bottom line, you will always here stories, & posts, from guys with stock automatic HHR SS, about weird boost problems,
& why is my boost low at different times, or at different speeds, or in different gears, ect, ect...
It's all to do, with the stock , ****ty HHR SS automatic ECM programming...
Please, friends, don't let friends, drive HHR SS automatics, with the stock ECM program.
Please, get a "tune", any "tune", any & all "tunes", are better then the stock ****ty Automatic tune…
With any "tune", your buggy will feel like, well, like your buggy should feel like, fast & powerful...
Our ECM is torque based…
Torque is delivered, based on the "Desired-Air-Load" table…
If you have an automatic HHR SS, with the stock "tune", you are being
restricted in so may ways, as GM really went to far, in limiting torque,
in order to prevent warranty issues, with the automatic.
These two tables, show how the stock program, bites, big time:
The 1st table shows torque being limited, in all but 3rd gear !!!!
The table gear headings, show an HPTuner error, should be 1,2,3,4,5 instead of 1,2,4,5,6, so where you see 100%, on the table, it is really 3rd gear, not 4th. Just a small typo error by HPTuner...
Most all "tunes", even the GMPP turbo upgrade "tune" have 100% power in 1st, 2nd, 3rd & 4th gears, with automatics...
You only get FULL power, in 3th gear, with the stock automatic HHR SS...


This table below, is the really ****ty automatic power curve, so bad, really, really, bad...

This table below, is a typical power curve, when "tuned"…

So, bottom line, you will always here stories, & posts, from guys with stock automatic HHR SS, about weird boost problems,
& why is my boost low at different times, or at different speeds, or in different gears, ect, ect...
It's all to do, with the stock , ****ty HHR SS automatic ECM programming...

Please, friends, don't let friends, drive HHR SS automatics, with the stock ECM program.
Please, get a "tune", any "tune", any & all "tunes", are better then the stock ****ty Automatic tune…
With any "tune", your buggy will feel like, well, like your buggy should feel like, fast & powerful...
Last edited by 2005HHRauto; Aug 14, 2014 at 08:54 AM.
I know this much based on my Dad's 2004 Silverado Duramax. Beastly thing with a Magnaflow exhaust. You can hear turbo spool in park when you rev, sure. But when there's nothing to be moved, it just dumps it. When you put it in gear, and you have the vehicles weight to move +1 occupant, it requires effort, and requires the motor, and depending on how much you put your foot in it, little or a LOT of the turbo. My Dad's truck sounds like a helicopter taking off when you get on it under load in gear. When it's parked and you rev the motor (little bit, since it's Diesel, too much is a bad thing) it just sounds like a pissed off Truck. haha


