[baltimoron]

I have been trying to soak up as much knowledge as I can quickly. I investigated a couple of mods, but then when I read the advice here, it seems like performance mods, like exhausts and CAI, are worthless without a tune afterwards. The way I understood it was that the computer "learns" the mods and programs the performance gains (HP and MPG) back to factory levels. Am I reading those comments correctly?

 

[rob the elder]

Yes, you are.

The factory tune monitors engine performance and adjusts settings to produce 260 ft pds of torque.

 

[chickenwire]

balt - I'm far from an expert, but I believe the "learn down" mode is moreso for the GXP (turbo) than the N/A. (At least that's what I've gleaned from feedback I've received.)

 

[The_Ghost]

Simple way around the learn down on the GXP.... Go to your local GM dealer and have the GMPP tune installed (about $750 is what I was quoted) or spend $300 on a trifecta (after you've done all your upgrades) and have them tune your car.....either way, you won't be sorry. Go with the GMPP only if your car is under warranty yet. On the GXP, don't waste your money on the CAI. Use that $300 for the tune or better intercooler pipes. Or a Windrestrictor!!! There are many different options for cars that are out of warranty for tunes....ranging from $300 all the way to $2000+ if you want it dyno'd.

As far as NA cars, I'm not sure.....

 

[King-Oka]

N/A cars do NOT have the learn down "feature"

 

[baltimoron]

N/A cars do NOT have the learn down "feature"

So, ballpark, if I got a GMPP catback and CAI, what kind of performance boost could I expect, individually and collectively?
Ron

 

[sirwm]

after a tune of any kind,
does this mean that you must use premium gas from then on ? :huh:

My car is stock and I use regular gas today...

 

[chickenwire]

It's also my understanding that the tunes will require premium sirwm.

Balti - as ghost said above, and many others have reiterated, the CAI doesn't gain you anything. The other end is the story - headers, cat, etc. then the tune.

 

[BellaVerde]

The Werks tune gave me a choice of tuning for 93 octane if I wanted it. But it was optional, so not all tunes require it.

 

[rob the elder]

So, ballpark, if I got a GMPP catback and CAI, what kind of performance boost could I expect, individually and collectively?
Ron

This has been discussed extensively in the past. For convenience I am including the results of my extensive absorbtion of info here:
1. Without a tune, no mod will provide any performance improvement
2. The only mod that all can agree on as adding performance is a high flow cat which has been measured to provide variously 16 - 18 HP gain
3. Charge tubes have been claimed to:
a. add some HP by a couple of members who swear they have data to prove it
b. not add any HP but does improve performance by delaying or eliminating the HP roll off at higher RPMs. That is, the stock charge tubes generate turbulence at RPMs of aroung 5000 and up that causes a reduction in HP measured. Smoother, less turbulent charge tubes do not reduce HP either at all or not as much thus allowing the motor to produce more HP longer after the peak HP region
4. The factory air filter is so well designed that no aftermarket CAI has demonstrated any performance gain.
5. The factory cat back in like manner is not a limiting factor. No after market catback has demonstrated measurable performence improvement

So
When asked I recommend
1. Get the DDM ProBeam
2. Get a tune (my favorite remains the GMPP because its warranteed and is less likely to cause problems down the road, not because its the "best" tune)
3. Get a high flow cat
4. Get the coolant check valves installed
5. Get the charge tubes of your choice to maximize power production if you drive above 5000 RPM on a regular basis.
6. Get the cat back of your choice to give you the sound and look you desire
7. Get something from Norm because you can
8. Never kneel in the passanger seat!:thumbs:

 

[ChopTop]

Do you have 2.0 or 2.4? If 2.4 recommended 2.0 like HP is to supercharge.

2.4 300-375HP Stage Kits (turbo)
http://www.performanceautowerks.com/catalog/advanced_search_result.php?keywords=2.4&x=0&y=0

2.0 GMPP (thought its been stated that the GMPP also disables software learn down feature*)
Solstice SKY HP & Torque ratings:
290HP @ 5,200 RPM
MT 340 lb,-ft of torque @ 3,600 RPM
AT 325 lb,-ft of torque @ 3,600 RPM

*assume this to mean with the learn down software being disabled any extra HP gained w/the addition of a CAI/Performance exhaust would be an additional increase to GMPP HP/TQ.

Good threads:
http://www.solsticeforum.com/forum/f63/lnf-mod-primer-60166/

http://www.solsticeforum.com/forum/f63/300-hp-stock-2-0-what-upgrades-74639/

 

[rob the elder]

GMPP (thought its been stated that the GMPP also disables software learn down feature*)
Solstice SKY HP & Torque ratings:
290HP @ 5,200 RPM
MT 340 lb,-ft of torque @ 3,600 RPM
AT 325 lb,-ft of torque @ 3,600 RPM

*assume this to mean with the learn down software being disabled any extra HP gained w/the addition of a CAI/Performance exhaust would be an additional increase to GMPP HP/TQ.

Good thread:
http://www.solsticeforum.com/forum/f63/300-hp-stock-2-0-what-upgrades-74639/

Actually there is not a "learn down" in the code, but the effect is the same. ECM settings are based on code that takes the sensor inputs and "looks up" the values that are "allowable or programmed" for the settings that go with the sensor inputs. The values are generally not calculated but a table - look up process. Somewhere around here I did a far too long explanation of this process, but basically the way I believe it works is that with the factory tune, the values in the table are such that the ECM will always be selecting values that will drive the engine output to the "perfect" 260 ft pounds of torque. So it does not actually learn anything. When the ECM receives inputs, it goes to the tables and uses the values it finds there. The combination of the values for the various parameters and the way the algorithms are constructed means that over a few key cycles, the ECM outputs will reach a new equilibrium state that matches 260 ft pounds. Between key cycles, the set points for the last operating cycle are remembered and form the starting location for the next operating cycle. Variation from cycle to cycle is limited such that the ECM cannot go through large changes in paramaters in a single operating cycle. Thus the appearance of learning over time.

The GMPP tune changes the target equilibrium state from 260 HP / 260 ft pounds to a new desired equilibrium state of 290 HP and 340 ft pounds. AND the algorithms used to select the parameter settings is modified to allow excursions in the equilibrium state beyond the 290 hp / 340 ft pounds point. There are still values that will result in the ECM code “learning down”, they are just much higher than previously.

I have not seen the new “learn down” points defined anywhere, but I suspect that they are set based on the upper safe limits are for the power train. Since we have evidence that 400hp cars are experiencing problems with the transmission and its believed that the axel splines begin to fail in that region, I would guess that the upper limit for GMPP is probably around 350 hp.

 

[TX08manualGXP]

and the reason they suggest 91 octane or higher is because the tune advances the hell out of the timing and lower octane gas combusts faster so you have the risk of detonation ( pinging and piston / head damage ) with less then 91 or better.

 

[rob the elder]

and the reason they suggest 91 octane or higher is because the tune advances the hell out of the timing and lower octane gas combusts faster so you have the risk of detonation ( pinging and piston / head damage ) with less then 91 or better.

:agree::agree::agree:

 

[baltimoron]

I have 2.4

Do you have 2.0 or 2.4? If 2.4 recommended 2.0 like HP is to supercharge.

I have the base 2.4, so all these answers after I asked what benefit the GMPP cat back and CAI might provide seem disingenuous, as they seem to pertain only to the 2.0. Boy, am I confused now. So, I would like to "start over".

Is my 2.4 exempt from the "learn down" back to factory settings that is common to the 2.0 GXP? If so, what mods would enhance performance on my 2.4 in terms of best bang for the buck on a limited budget?

 

[King-Oka]

Yes the 2.4 will hold whatever power you add to it. The comment about a high flow CAT still applies. $375 from DDM I believe and you'll get better exhaust flow. Or if you're up for it -get their long tube header for 850ish, which includes a CAT

I didn't find ECM tunes offered much of a kick, so eventually I Supercharged. That gets you to GXP levels (stage 2 adds 90HP, Stage 3 adds more). See DDMWorks website for actual HP adds and dollars.

I also agree with RTE - Suspension upgrades such as DDM Backbrace are worth the investment.

 

[shabby]

Actually there is not a "learn down" in the code, but the effect is the same. ECM settings are based on code that takes the sensor inputs and "looks up" the values that are "allowable or programmed" for the settings that go with the sensor inputs. The values are generally not calculated but a table - look up process. Somewhere around here I did a far too long explanation of this process, but basically the way I believe it works is that with the factory tune, the values in the table are such that the ECM will always be selecting values that will drive the engine output to the "perfect" 260 ft pounds of torque. So it does not actually learn anything. When the ECM receives inputs, it goes to the tables and uses the values it finds there. The combination of the values for the various parameters and the way the algorithms are constructed means that over a few key cycles, the ECM outputs will reach a new equilibrium state that matches 260 ft pounds. Between key cycles, the set points for the last operating cycle are remembered and form the starting location for the next operating cycle. Variation from cycle to cycle is limited such that the ECM cannot go through large changes in paramaters in a single operating cycle. Thus the appearance of learning over time.

The GMPP tune changes the target equilibrium state from 260 HP / 260 ft pounds to a new desired equilibrium state of 290 HP and 340 ft pounds. AND the algorithms used to select the parameter settings is modified to allow excursions in the equilibrium state beyond the 290 hp / 340 ft pounds point. There are still values that will result in the ECM code “learning down”, they are just much higher than previously.

I have not seen the new “learn down” points defined anywhere, but I suspect that they are set based on the upper safe limits are for the power train. Since we have evidence that 400hp cars are experiencing problems with the transmission and its believed that the axel splines begin to fail in that region, I would guess that the upper limit for GMPP is probably around 350 hp.

This post should be stickied and referenced to every time someone mentions "learn down mode". I was so sick of hearing that term it drove me mad :willy:

 

[rob the elder]

Thanks

I have a version of that saved on my laptop and cut & paste it I have the same reaction. But, for a long time many of us did not understand how the ECM code really worked either

 

[baltimoron]

Yes the 2.4 will hold whatever power you add to it. The comment about a high flow CAT still applies. $375 from DDM I believe and you'll get better exhaust flow. Or if you're up for it -get their long tube header for 850ish, which includes a CAT

I didn't find ECM tunes offered much of a kick, so eventually I Supercharged. That gets you to GXP levels (stage 2 adds 90HP, Stage 3 adds more). See DDMWorks website for actual HP adds and dollars.

I also agree with RTE - Suspension upgrades such as DDM Backbrace are worth the investment.

Thanks! That's the kind of simple answer and advice I was looking for. Thanks for dumbing it down for me. :thumbs:

 

[chickenwire]

balti - Now that we have you on the right track, know this about the tunes. They basically adjust the data in the "tables" that Rob mentioned to optimize the engine's performance to match your hardware. That is why members here advise you to make all the mods you want, THEN get the tune.

The tune on the 2.4 N/A doesn't appear to add a lot, but one thing it does is remove the "nanny controls". For instance, the throttle is "by wire" - there is no cable just a throttle position sensor that sends a signal to the ECM which then increases the fuel delivered to the engine. One of the functions gradually "ramps" the increased fuel flow. The tune will get rid of this so the throttle becomes much more responsive. I've read that many people consider this worth the price of the tune alone!

I've also read many members here raving about the level of service and support from DDM. I'd give them a call and chat with them as it seems they will give you straight direction and all the education you need in a short discussion.

Oh, and can you change your avatar. It takes me at least fifteen minutes to read your posts 'cause I keep getting distracted.

Or at least send a link to the image. Unless those are your sisters, daughters or other family members, in which case forget I said anything.