Tuning the LLNF

[cobalt123]

totally jacked this but i dont care


It still needs alot of input from users on this site to make it a truly great thread. The purpose of this thread is to elaborate on how tuning an LNF is accomplished and the different tunes available for the LNF and not to teach you how to tune which BYT*SS*TURBO's thread does a great job of explaining the basics of (LNF Tuning Basics w/HPTuners - Cobalt SS Network). Wherever you see a question mark and you know the answer please let me know.



Basics of How a Tune Works on the LNF
written by Terminator2

The Gasoline Direct Injection (GDI) LNF uses a Bosch E69 GDI ECM. This ECM is a torque based engine controller containing approximately 2,500 tables that control all engine functions. There are approximately 600 tables that control fueling alone. A typical ECM contains only approx 250 tables total by contrast. A Gasoline Direct Injection (GDI) based fuel injection system is much harder to control and optimize than a typical Multiport EFI system which is why there are so many tables In the ECM that control fueling.
At the heart of this ECM is its torque based control system that uses driver input via pedal position to determine driver desired torque. Think of it as 100% pedal is equal to 100% driver desired torque. The driver desired torque value is fed into the Desired Airload table (DAL) which uses driver desired torque (pedal position) vs RPM to determine actual throttle postion. By raising or lower the DALs one can effect how the car reacts to pedal input from the driver. You can make 50% pedal 100% actual throttle opening or vise versa by raising or lowering those values. The DALs are regulated by the Maximum Airload Torque table (MALT) whch determines the percentage of actual airload allowed based on RPM. The Combination of the DAL and MALT helps determine actual throttle postion and does regulate the wastegate to some degree but does not allow for the desired boost level to be raised above 238 kPa, 34.5 psi absolute or 20 psi guage without modifying another table that we HP Tuners users do not yet have access to.
The GM stage tune rasies this desired boost ceiling to 285 kPa, 41.5 psi absolute or 27 psi gauge without raising the Desired airloads. The Superchips Tune also raises the desired boost levels without changing the desired airloads. Vince's infiniboost tune tricks the ECM into thinking it is seeing 238 kPa even though it may be seeing up to 300 kPa. We HP Tuners users have to runs external wastegate regulators or boost controllers to hold the boost levels above 20 psi until they decide to crack more of the ECM for us.
There is debate as to what is proper as far as what is Air to Fuel (A/F) mixture is appropriate for the LNF while in Power Enrichment Mode (PE) at Wide Open Throttle. PE ratios are expressed as Lambda where 1.00 Lambda = 14.69 A/F mixture when using gasoline. The Stock GM Tune and Stage one tune both use the same PE ratios of 0.95 to 0.87 lambda or 14.0 - 12.8 A/F. Most Trifecta tunes use 0.80 - 0.84 PE Lambda or 11.8 - 12.4 A/F. The Superchips tune uses uses 0.85 PE Lambda or 12.5 A/F. HP Tunes will vary according to who is doing the tuning. I have seen anywhere from 11.4 to 14.0 PE A/F used depending on the tuner. PE A/F is influenced by Power Enrichment VS Time which is better known by most as the catalyst overtemp protection table or COT Lambda table. After a certain time at WOT once the ECM models a catalyst temperature of 1700* the ECM will richen the A/F mixture to as rich as 0.711 Lambda or 10.45 A/F at WOT. Most change those values to match their PE Lambda Table or if they are catless they set all values to 1.00 lambda to disable the extra enrichment.
Ignition and cam timing is another aspect of tuning this ECM as the LNF has variable valve timing. The VVT is controled by cam phasers on each camshaft. The LNF has 4 sets of basic timing tables based on load, RPM, and Camshaft postion in relation to each cam's minimum and maximum states. Although there are more timing tables these are the main ones we are concerned with. Timing theories vary according to application but there is one universal truth. There is a point at which adding more ignition timing will actually cause torque and conversely HP loss. There is always a sweet spot where the mixture burns completely and just at the right time so that maximum cylinder pressure is reached right as the piston comes to Top Dead Center (TDC). That results in the the most work possible being performed on the piston (Large Force Acting on the piston for the most time possible) and hence the most torque output possible at that RPM. If the mixture burns too long from running too much ignition timing it will reach peak cylinder pressue well before TDC and the results will be spark knock and power loss, but if there is too little ignition timing run the mixture will not have sufficient time to burn completely and peak cylinder pressure will be reached after the piston passes TDC and the result will be less torque produced (Smaller Force acting on the piston for less time) The LNF is no different. It uses less WOT timing than any other engine I have ever seen partly do to the efficiency of the Direct Injection which produces much better fuel atomization and the comparatively lean mixtures GDI cars are known to run at WOT. Lean mixtures burn faster and hotter and require less timing because they burn quickly. Rich mixtures burn slower and at lower temperature and require more timing to burn completely.
There are over 20 camshaft tables but the only ones most would modify are the Intake Cam Main Warm table and the Exhaust Cam Main Warm Table. Many have wondered what the units in those tables are as they are undefined in HP Tuners. They are based on the camshaft's base circle. As I understand, the units influence how many degrees from center the camshaft is based on its base circle. So it is the camshaft itself that gives meaning to those units. That is why the values in the scanner are so much different than the values in the tables themselves and why it is possible to have a negative value in the table but a positive value in the scanner. Some have found small gains in top end HP by advancing the intake cam 2-3* in the upper RPM and upper load regions of that table. When you advance the intake or the exhaust cam you are asking it to open sooner. The throry behind a slight advance in intake cam timing is to open the intake valve a little sooner so the cylinder can take in more air. Exhaust cam tuning theory is the opposite principle. You want to leave the exhaust valve shut as long as possible so that maximum cylinder pressure is reached before the exhaust valve opens. The problem is if you wait too long to open the exhaust valve peak cylinder pressure already have been reached before the exhaust valve opens. That means either knock will ensue or the piston will already be past TDC and the ability to generate peak torque will be lost.


What is "Learn Down" and How Does it Work
written by Terminator2

The "Learn Down" feature. Because the LNF's ECM uses torque based controls it is much more advanced as far as limiting or adding to the torque that is desired from it. All modern ECMs that I have seen have Torque Management (TM) tables, and the LNF is no exception, but its entire engine management system is built around Driver Desired Torque vs Actual Torque Output. Driver desired torque is based on Pedal Position, RPM, Desired Airload, and Maximum Airload Torque. Those values determine Optimum Engine Torque which calculates engine torque output based on 1.00 Lambda. The Lambda Efficiency table changes calculated engine torque based on A/F Ratio expressed as Lambda. Leaner than 1.00 Lambda will produce less actual torque, and richer than 1.00 Lambda (up to a point) will produce more actual torque output. The "Learn Down" that most notice occurs when adding mods or driving in very cold weather they notice the boost pressure values have gone down. The ECMs torque based controls are to blame for this. If breathing efficiency is increased either from adding mods or from a denser air charge the ECM compensates for this by decreasing its Desired Boost pressure values. It does so because Actual Torque Output is modeled as greater than Desired Torque output. The GM Stage 1 tune raises the Desired Boost and Actual Torque output levels but does NOT completely remove the learn down but it does raise it. Other Tunes work the same way. They do not completely remove the learn down they merely raise it to a level that the car cannot acheive in the first place. Think of the learn down more like a target airload level or target torque output level. If you add mods or change the charge air density the ECM will sense that it is reaching its target torque output much more easily than before. That is not to say that adding mods without a tune will produce no gains at all. It is possible when adding mods like a catless DP and an Intake to make more power than stock even without being retuned. Although the gains are much larger if you retune the car I have seen evidence that even thousands of miles after adding mods a car will still dyno higher than stock. I have seen a stock tune LNF with an Intake and Catless DP make 254 whp and 272 wrtq thousands of miles after first adding the mods. That car stock on that same dyno would make closer to 240 whp and 250 wrtq.

[cobalt123]

Why Canned Tunes Don't Compensate For Mods
written by Terminator2

Canned tunes like the PPC tuner and Superchips Tuners are designed to work with stock parts like the stock intake and DP. Because of this thay have the same stock MAF tables as the stock GM tune has. If one adds an intake neither one of these tunes is capable of altering those tables necessary to make the car run at its best. Only a custom tune using HP Tuners or Trifecta's software can change those MAF tables to match an aftermarket or modified stock intake. Catless DPs allow for the extra enrichment that is intended to protect the stock catalyst material (COT) to be removed thus allowing for more consistant A/F even while under long periods of WOT. Also the better breathing from an aftermarket DP allows, in most cases, for a little more timing advance to be added without causing knock. That normally creates a slight increase in power. None of the canned tunes will adjust for different intakes or DPs in the same way a well contructed custom tune can.


What You Should Know Before Getting a Tune
written by tom.g
Aside from the GM Turbo Upgrade Kit (GMS1) tune all tunes are aftermarket and therefore technically may void the warranty so please bare this in mind if you are going with an aftermarket tune. Also keep in mind that when GM designed the Turbo Upgrade Kit (GMS1) they had longevity and reliability in mind and therefore spent a lot of time and money on research and development to ensure that this tune will work well with the vehicle for a long period of time. The GM Turbo Upgrade Kit (GMS1) tune is the only tune which comes with upgraded MAP Sensors (3 Bar vs 2 Bar) these are a higher quality sensor which can read higher boost more accurately, the biggest benefit to these sensors as far as I can tell is that if you decide to go with a more aggressive aftermarket custom tune these sensors will be beneficial for creating big power. That being said there are quite a few other options for tuning your LNF. From the inexpensive modest tunes which can be easily flashed on to the vehicle to the custom tunes which can turn your LNF into a monster the comparison below is as unbiased as possible and will hopefully help you make your decision.

The other thing to keep in mind when deciding to get a tune is driveability. Adding power to a FWD car does increase the amount of torque steer (the feeling you experience when going WOT and having the vehicle want to pull towards either the left or the right) and will almost certainly wear your tires, clutch and possibly brakes faster. However if you can live with the above then get a tune as this is the single most effective modification you can do to really "wake up" our already quick cars.


Different Tunes Available for the LNF
written by tom.g

Below are the main tunes listed available for the LNF, and a comparison on some of their major points. I really need first hand thoughts and facts on these tunes from users who are using these tunes to properly finish the comparison. (Tunes are in alphabetical order)



GM Turbo Upgrade Kit (GMS1)
Cost ~ $500-1100 + ~$200 (install)
Power Increase(Over Stock) 30-40WHP / 50-70WTQ
How is Tune Installed New sensors (included with kit) are installed by dealership and then the new tune is flashed on by the dealership.
General Info Generic / Canned Tune made by GM
Warranty Issues None this is a factory tune
Driveability Overall driveability improved. Torque Steer is more noticable.
Pro's Simple and basic dealership installed tune.
Con's Some beleive this tune runs a little lean in the mid range. Expensive. Tune quickly begins loosing power after 6000RPM. Modifications are not/can't be tunned for.
Rev Limiter Raised to 6500RPM
Fuel Consumption Some have noticed an increase of 1-2MPG
# of Blown Pistons 1?
Link(s) for more info & purchase 19212670 Cobalt, Solstice, HHR Stage Kit 19212670 - Crate Engine Depot GM Parts Direct: Your direct source for Genuine GM Parts




HP Tuners
Cost ~$200 - 700 (Depending on if a local tuner tunes for you or if you buy the VCM Suite)
Power Increase(Over Stock) 40WHP-100WHP / 50WTQ - 100WTQ (Depending on how agressive tune is) ?
How is Tune Installed 1. VCM Suite is purchased and the vehicle is tuned by the user him/herself. 2. If VCM Suite is purchased however the user wishes to purchase a tune this can be done via e-mail and then uploaded to vehicle. 3. Local dealer tunes the vehicle via VCM Suite.
General Info This is a custom tune which has can be tailored exactly to the wants/needs of the customer and if performed by a skilled tuner can offer massive power gains.
Warranty Issues Can be flashed back to stock ("write entire") if tuner lives in close proximity or VCM Suite was purchased, however if GM digs deeper they will see the PCN counter does not match what their records show.
Driveability ? (Depending on tune)
Pro's Tunes can be from mild to wild. 420 code can be removed therefore people with Catless Downpipes will no longer see a CEL.
Con's If inexperienced tuner tunes the vehicle there is a chance of engine damage.
Rev Limiter Whatever is requested
Fuel Consumption ?
# of Blown Pistons 2?
Link(s) for more info & purchase HPTuners.com >> Performance At Your Fingertips




PPC (Hahn)
Cost ~ $1000
Power Increase(Over Stock) 35WHP - 40WTQ
How is Tune Installed Unit is plugged into vehicles OBDII diagnostics port and the new tune is uploaded, the stock tune is then stored in the devices memory and can be re-loaded if necessary.
General Info Hand Held Tuning Device. Generic / Canned Tune
Warranty Issues Can be flashed back to stock for dealership visits, however if GM digs deeper they will see the PCN counter does not match what their records show.
Driveability ?
Pro's Updates via interent are possible when released.
Con's Very expensive. Modifications are not/can't be tunned for.
Rev Limiter Raised to 7000RPM in 1 and 2 Gear 6500RPM in 3-5
Fuel Consumption ?
# of Blown Pistons ?
Link(s) for more info & purchase Cobalt 2.0 Performance http://www.turbotechracing.com/produ...dcategory=5614




Superchips
Cost ~ $300 - 500 (Depending on Flashpaq or Cortex)
Power Increase(Over Stock) 20-30WHP - 40-60WTQ
How is Tune Installed Unit is plugged into vehicles OBDII diagnostics port and the new tune is uploaded, the stock tune is then stored in the devices memory and can be re-loaded if necessary.
General Info Hand Held Tuning Device. Generic / Canned Tune
Warranty Issues Can be flashed back to stock for dealership visits, however if GM digs deeper they will see the PCN counter does not match what their records show.
Driveability ?
Pro's Superchips offers a limited 2 year warranty if the Cortex tuner is purchased. Updates via interent are possible when released.
Con's Sensitive first gear. Modifications are not/can't be tunned for.
Rev Limiter Raised to 6500RPM ?
Fuel Consumption ?
# of Blown Pistons ?
Link(s) for more info & purchase ?




Trifecta
Cost $200 - 500 (Depending on if tune is done by a local tuner, the borrowed scan tool or USB cable is purchased)
Power Increase(Over Stock) 40WHP-100WHP / 50WTQ - 100WTQ (Depending on how agressive tune is)
How is Tune Installed 1. Trifecta lends the purchaser a handheld tuning device with which the new tune is flashed on to the vehicle, a few logs are performed and sent via e-mail to Trifecta if the tune needs to be tweaked they are done over e-mail handeld device is then returned to Trifecta. 2. Local Trifecta dealer installs the tune from Trifecta on to vehicle and then acts as the liaison between Trifecta and the purchaser for aditional tweaks to the tune (only Trifecta works on the tune not the dealer). 3. A usb-OBDII cable is purchased from Trifecta and then the tune is uploaded

[cobalt123]

and tweaked via e-mail.
General Info Custom Tune performed by Trifecta only. Tune has been written to match the gm records and is undetectable at this point this tune is called the Stealth Tune. Infiniboost tune is the only tune capable of exceeding 23PSi without the use of the "pill mod" or external wastegate controller.
Warranty Issues Tune was designed to be "hidden" from a GM Tech II Tool which is the standard tool used to determine engine calibrations. And if users with the cable flash back to stock this quote from Trifecta explains it best "As far as I know, if the ECM has been flashed back to stock there is absolutely no way for the dealer or engineering department to discover it was flashed. There are no reflash counters in the LNF ECM that I have found."
Driveability Similar to stock
Pro's Tunes can be mild or wild. Trifecta has unlocked Fan Control and Fuel Tables. 420 code can be removed therefore people with Catless Downpipes will no longer see a CEL as well as other CEL`s. Boost tables that allow for continual boost throughout the powerband which increase power and reduce (if not eliminate) clutch slippage. Trifecta offers updates for their tunes when new material/information is found or when modifications are made to the car.
Con's ?
Rev Limiter Whatever is requested
Fuel Consumption Generally improved (marginally)
# of Blown Pistons 2 ?
Link(s) for more info & purchase Trifecta Performance Custom Tuning :: How to Buy Cobalt Tuning Trifecta Performance Custom Tuning :: Dealers, Independent Tuners and Affiliates




ZZP
Cost ~ $200
Power Increase(Over Stock) ~35WHP - ~70WTQ
How is Tune Installed The tuned PCM from ZZP is switched out with the stock PCM, the stock PCM can be returned to ZZP for reinbursment of core charge or kept for future switching if so desired.
General Info Seperate PCM with tune flashed on. Generic / Canned Tune
Warranty Issues Tuned PCM can be switched out with stock unit, however if GM digs deeper they will see the PCN counter does not match what their records show.
Driveability ?
Pro's This is a spare PCM that has been flashed by ZZP, therefore it is very simple to switch between the stock PCM and ZZP's tuned PCM. 420 code removed therefore people with Catless Downpipes will no longer see a CEL. Modifications can be be tuned for if requested when ordering ECM's.
Con's ?
Rev Limiter Typically raised to 7000RPM however can be requested to be different
Fuel Consumption ?
# of Blown Pistons ?
Link(s) for more info & purchase Cobalt & Ion ---> ZZ Performance

Glossary
written by tom.g & Terminator 2

LNF - The 2.0L Direct Injected Turbocharged EcoTec Engine Made by GM and found in the 08-10 Cobalt SS, HHR SS, Pontiac Solstice and Saturn Sky
GDI - Gasoline Direct Injection
ECM - Engine Control Module
ECU - Engine Control Unit
PCM - Powertrain Control Module (Interchangeable with ECM and ECU)
BCM - Body Control Module ( ESC, ABS, Mileage is stored here)
TCM - Transmission Control Module
Multiport EFI - A system where fuel is injected into the intake manifold and then into the combustion chamber
DAL - Desired Airload Table
WOT - Wide Open Throttle (100% Throttle)
MALT - Maximum Airload Torque Table
PE - Power Enrichment Mode
Lambda - A way of expressing the air fuel ratio, a Lambda Value of 1.0 = 14.69 Air/Fuel
VVT - Variable Valve Timing
TDC - Top Dead Center
TM - Torque Management Tables
Canned Tune - A generic tune created to cover all LNF motor's. These tunes work well but not great as every single car is a little different and as a result only logging and re-tuning will make the tune ideal for each particular car.
DP - Down Pipe (All You Need to Know About Downpipes - Cobalt SS Network for more info)
FWD - Front Wheel Drive
WHP - Wheel Horsepower (measured via dyno)
WTQ - Wheel Torque (measured via dyno)

[Tuner923]

interesting read... I don't know if many people are going to understand what they are reading but still good info!

[cobalt123]

yeah its here if they want to read it