GM Stage 1 LNF

[cobaltssoverbooster]

if you have the 2.5 factory sensors you cannot copy the map sensor data over or it will run horribly. everything else should be fine to use though as long as you dont have any major changes like removed rear o2 or maf relocate.

[DrLoch]

My guess is that he hadn't changed the sensor yet

[Brettworth]

Didn't change the map sensors. So I can use the new MAF hz data, but don't use the map data?

[PSYKOSTEVO]

I'm wondering why you are worried about the GMPP Stage 1 tune, when you can tune the stock calibration just fine for virtually all setups.

Are you needing to run a 3 Bar T-MAP to fine tune a bigger turbo or something?

[Brettworth]

I was under the impression the best way to go about it is to start with the stage 1 tune, and play with that. Why reinvent the wheel when you can start with a well engineered one?

Now I'm also thinking that you really need the new MAF values to allow the car to develop more power. If I understand that correctly, you can turn up the boost, change the air intake, and/or change the downpipe, and after two runs, the ECM will bring the new found power back to OEM levels.

If any of this is wrong, please let me know. Totally trying to suck up all this information like a sponge, and also do a million other things around the house and what not.

BUT - I would like to thank everyone that has replied to me thus far. Very awesome of everyone.

[cobaltssoverbooster]

the best way is to start with the stage 1 tune copied and pasted into your factory file but you dont need the map sensor data from it unless you change the map sensors out to the 3 bar ones that come with the kit. if your boosting at 23 psi or less you can use factory sensors and values. there are a lot of reasons the ecu cuts boost down after parts changes, the maf values are for setting fuel requirement they dont turn the power level back down. i will post another tune file for factory 2.5 bar sensors as a reference tonight. I will include some instructions as well. with that said it will take me a while to type out so please be patient.


psychosteve its been since like 2010 since ive seen you post, glad to see your still around.

[Brettworth]

Sweeeeeeeet!

[cobaltssoverbooster]

Before I start, tuning is performed by the users at the users risk and knowledge limitations. Therefore, if you (the user) suffers from failures due to errors in tuning profiles and or lack to verify safety concerns then I will not be held responsible/accountable for your losses. I will not pay out any claims for lost mechanical or electrical components. With the disclaimer out of the way be warned, this is not meant to be a finalized tune file and requires finalization by you (the user). It is highly recommended to spend time on a loading dyno to fix any errors that you may have problems trying to fix on the road and/or to set the final power run settings.

This tune is from a 2008 GMPP Chevy Cobalt SS. The file has been modified to retain the correct data for the factory 2.5 BAR Non-GMPP sensors. Do not flash this file into your ecu or it will fry it! Open this file as a compare file in the VCM Editor and copy the files from the compare to your original file. Do not save over your factory file! Create a duplicate by first saving the factory as "Factory GM" then perform a save-as and rename the file to an alter name of your choice such as "GMPP2.5BAR". The Chevy cobalt is very similar to the hhr file and you will find very little discrepancies between the two. If you have a kappa platform (sky redline/solstice gxp) be aware some axis labels are different and require hand blending to match up properly. You can modify axis values to match if you wish to copy and paste data over but that is up to you (the user).

Pre-Tune Checks:
A) Check Spark plug gaps .030" purchase new ones if more than 15k miles have been put on them. they are cheap and provide consistent results when new. NGK "6" Heat range or equivalent is one step colder than factory. Factory ACDelco plugs have been great for many people, if you don't want to shift brands those will be fine.
B) Check belts and alternator output. Any flaws in these will cause tuning errors as there are internal voltage corrections applied when the voltage starts to drops. This will throw your data results off not to mention piss you off when you realized you lost a belt and any other parts it decided to take with it on its way out the engine compartment.
C) Check coolant operating temperature. Should be steady and never exceed 215*
D) Start with fresh gas. If your car isn't a daily driver and has been sitting for a month or two, then its time you drive that tank to the bottom and fill it up with fresh fuel for tuning. Choose 91 octane pump or better from now on!
E) Tighten every single charge pipe clamp again before tuning. I cant tell you how many times myself and others have missed a damn clamp and wasted precious tuning time.
F) Clock your Knock Sensors to the GM specs. Harness should exit the knock sensor pointing to the from of the engine 90* (horizontal, or parallel to the crank centerline.) This doesn't always fix errors but its where GM wants them so make sure they are there.
G) Although this isn't a checkable item this is still an important step to keep in mind as it blows frequently. Your clutch is eventually going to start slipping, now is the time to start saving for a stage 3+ or better unit. Don't forget to factor in the price for a new flywheel as they are not always able to be saved by the machine shop. DON'T SKIMP ON THESE PARTS! it takes a lot of time to fix something wrong with these parts so the longer you stay out of there the better.

Now follow these steps:
1) close all hptuners files.
2) open your second factory save "GMPP2.5BAR"
3) open this attached file you saved to a location such as "desktop" or "downloads"
4) go section by section switching between the two files copying data from the compare file to the main file. *note* I recommend making all the changes on one page at a time then saving your base file with the compare still open. After saving, all the tables that match should revert back to the normal greyscale color. if you missed one it will be a different color thus notifying you that you have missed a change.
5) once you feel you are done, perform your final save. Go through every tab once more and verify that you have not missed any values.
5a) Now you should have two complete files, one stock and one modified. Your stock file is there so you can revert back to it in an emergency. The lnf/ldk/lhu computers have been known to corrupt data when flashing and thus it is safe to always have a file on backup incase something went wrong.
6) Roll your windows down, install a battery charger to your vehicles charging post or direct to battery, and install a charger to you laptop. Turn off all accessories, radio/ac/fans/headlights you name it turn it all off. We do this to ensure a stabile and consistent voltage to the ecu during the writing process. If someone walks up to talk with you, the simple act of opening a door or rolling a window down can cause enough voltage fluctuation that it could possibly cause data corruption or worse ecu failure. To save your ecu always follow these steps when flashing.
7) Turn ignition to full dash on without the engine running. now select write calibration. everything you made changes to will now be applied to the ecu.
8) once the software tells you your flash is completed you may then turn the ecu off by turning the key to power off. Start your vehicle to observe idle quality and activate your scanner to verify you have no major problems that need fixing on an immediate timeframe.
9) if you are good at idle there is only one thing left to do...drive it. Drive you vehicle slow with low load (old folk driving skills) and verify the low load data before you move up. The idea is to verify your data in steps, read until you get some errors then fix them. Move slowly up the load range performing the verification process until you finally get to wot loads. Once all data is verified you are to a safe point and can start making finalizing adjustments.
*note* every time a change is made it will effect numerous tables related to the ones you are making changes to. Example: If you change airflow, you will have to adjust fuel to re-correct the error caused by adjustment.

Things to understand in this tune file:
1) the map sensor curve is bone stock GMPP Cobalt. The maf base table is left as a multiplier of 1.0 to let the maf be the sole source of airflow dynamic calculations. (the maf base table is secondary to the maf curve, that makes the maf base a modifier table and we want them turned off or neutralized until darn near the very end of the tuning process)
2) Cam tables are a smoothed and slightly modified version of the factory cams. Notice warm and cold tables are the same for both cams. The ecu will pick a table based on varying factors, if we make them the same then it will not have a choice of tables. It will be forced to run what you command.
3) the knock sensor cam tables are mirror images of the main tables. if for some reason a corruption of data allows the ecu to activate this table although it is set to off, we don't want it picking a cam angle of "0". Instead we want it to run what we are commanding. Don't forget to copy any main cam changes you make into this table. Keep it updated.
4) Cold Start Cams/ Cat warm up. These are set to match the factory cams. some people prefer locking them into the base idle angle but I prefer to leave them the same as the main table in case you are in an emergency and need to drive away without letting the warm-up cycle complete.(bypassing the warm-up cycle is not recommended.) On a further note, if your vehicle is not over 160* on coolant operating temperature then do not perform any power runs. let the coolant temp come to full thermostat temperature before making any heavy load pulls.
5) Idle Cam positions are set to the mechanical rest position, full cam separation. This also helps idle stability later down the road.
6) lambda table is set fairly conservatively. this is by no means a finalized table but I left it adding fuel in early and slightly towards the richer side to help cool cylinders. If you experience detonation, make fueling adjustments and ignition adjustments to remove the errors.
7) Cat Over-Temp protection turned off
8) if your tuning for 23 psi you can kiss your factory cat goodbye anyways so there is no need to protect it. (catalytic converters and ko4 turbochargers are consumable items, get used to it)
9) ignition tables are smoothed and slightly raised in the big end by 2*. As like the cam tables all 4 match each other perfectly to prevent ecu control inconsistencies.
10) Ignition tables such as IAT/ECT/AFR corrections are disabled. base ignition must be set and corrected first before you can change make changes for specific conditions. (takes you back to all modifiers are deactivated/neutralized)
11) all torque management tables set to allow 100% power output. The max air load trq table is a trq output calculation table, raising above a realistic output level causes errors and inconsistencies. I raise it to 100 at 3k rpm since that's about where the factory turbo spools and hits hardest. If you have a large turbo you would push the 100 value back to where it hits spool. Leave the lowest value at the factory then click interpolate horizontal axis to auto tune the cells in-between.
12) Desired air load table caps out at 255 since that is the maximum limit the intake map sensor can see. Even with a 3bar setup 255 is the max value. 3k to max rpm highest load cell set to 255 max. 2800 rpm to max rpm and 70% load to max load all cells global smoothed twice. hand smooth any stray errors.
13) optimum spark set to a starting point. do not adjust them further until you have explored all the options and fully understand these tables. they can be dangers and at the worst can be life threatening.
14) Optimum Trq, massaged to match the DAL table requests. should be fine here with minor modification if required. I've honestly raised it to such value and left it unless running a larger frame turbocharger.
15) turbocharger settings have been modified to remove upper pressure cap limits. Due note exceed the map sensor will still cause a map code to let you know you have an error. I recommend targeting 22 psi on factory sensors so you have some error range left on the map sensor. trust me 22psi will still be a monster to drive.
16) waste gate duty cycle set low in max rpm/load range to prevent initial over-boosting. I understand it may boost lower than you have now but its best to start under your target and work up to it than it is to overshoot it and be screwed mechanically.
17) the last setting is in the engine diagnostics tab. There is an over-boost feature which is tied heavily to the "learn down" that was mentioned earlier in this thread. along with some of the other changes that have been made you will no longer see a "learn down". Values raise to highest rpm range where the boost feature will never be able to activate.

if you have any questions about changes please refer to the tuning threads listed in my signature. Hopefully you have read them already and have a head start on the process. Everyone since 2008 has worked hard and made their data public for the sake of the community. Please give them credit where it is due and do not steal their information, we will know.
Driver Demand/Torque Based ECU's are in there own field when it comes to tuning. Do not let the frustration get to you or you will run into problems; some you may not be able to recover from without a machine shop. Post your files and questions in the forum to get help when you need it. Be patient for responses and if its taking to long revert your tune back to an earlier lower power tune to remain safe for regular operation. These ecu's are very picky about tables being uneven or rough. Keep your data changes as smooth as possible between cells to prevent large variations that will cause further errors to arise.

[DrLoch]

CSSOB, nice write up.... I didn't see the file, unless I missed it. I've been spending a lot of time reading yours and gmtechs informational posts on the LNF. I would like to thank everyone involved with the learning process.

[Brettworth]

CSSOB, nice write up.... I didn't see the file, unless I missed it. I've been spending a lot of time reading yours and gmtechs informational posts on the LNF. I would like to thank everyone involved with the learning process.

Exactly what DrLoch said. Thank you. I just rolled 126K, so I'm going to order up some new spark plugs.

I took the HHR to the drag strip last week, no issues with anything in stock form, but the mechanical should get inspected anyway.

Can someone explain why the MAF hz values are changed?

[cobaltssoverbooster]

i dont understand why it didn't take the file. i uploaded to the system and inserted it. i will have to go back and try again, it will be tonight before i get to try and correct the problem.
sorry it didn't take guys, i honestly dont know what happened.

maf hz get change to correct the fueling requirement under the new high boost pressure. normally factory floats around 15 psi and the tune from gm runs in the lower 20's. the increased boost will also increase airflow so if you dont adjust the maf to let the computer know there is more air coming in then you will always run very lean.

[cobaltssoverbooster]

well it ended up saving to the hpt forum file system so it should be there now.

[DrLoch]

CSSOB thanks for your efforts, it is appreciated.

[Brettworth]

So going by that (hz talk), Is it safe to assume that on most vehicles, if you add a cold air intake, or remove some restrictions, you would have to tune for it?

I was under the impression that the MAF would see more air, and the ECM would correct for it?

Thanks for the help as always!

[cobaltssoverbooster]

The ecu would use fuel trims to correct for it but you want it to use the correct values the first time so yes you would tune it.

[PSYKOSTEVO]

psychosteve its been since like 2010 since ive seen you post, glad to see your still around.

Thank you sir......it has been a long time. I stay busy though :-)

[PSYKOSTEVO]

So going by that (hz talk), Is it safe to assume that on most vehicles, if you add a cold air intake, or remove some restrictions, you would have to tune for it?

I was under the impression that the MAF would see more air, and the ECM would correct for it?

Thanks for the help as always!

Let me answer this for you. Yes, the MAF will see more air. That's what that sensor reads.

The MAF sensor essentially says to the engine "The air is moving this fast, and its at this temperature." Based on the tune that's in the ECM, that is calculated into the AMOUNT of air that is coming into the engine. The Cold Air Intake allowing more air into the engine would only mean that the MAF sensor would be feeding the ECM a signal to tell it that the additional air is coming. In theory you would be bringing in a different speed of air at a different temperature.

When you absolutely positively must get a retune on the MAF table is after you introduce a cold air intake that changes the inner diameter of the tubing where the MAF sensor sits. If you change the inner diameter you totally throw off the calculated airflow amount in the ECM, because ECM relies on the MAF housing diameter to be a constant size and never change.

That being said, no 2 stock MAFs read exactly the same voltage vs airflow and there is a margin of error allowed by the ECM before issues arise. You car will always run more predictably with a fine tuned MAF table regardless of the intake you choose to use.

[PSYKOSTEVO]

The ecu would use fuel trims to correct for it but you want it to use the or rest values the first time so yes you would tune it.

Would only use fuel trims to calculate for it at part throttle, at WOT there is no correction on most engines. The LNF would use a Wideband O2 error % at WOT, but it's not an ideal scenario when you could just tune the MAF more closely to perfect in the first place.

[cobaltssoverbooster]

Would only use fuel trims to calculate for it at part throttle, at WOT there is no correction on most engines. The LNF would use a Wideband O2 error % at WOT, but it's not an ideal scenario when you could just tune the MAF more closely to perfect in the first place.

I left that detail out, thanks for clarifying for everyone.