Originally Posted by Kennyspec

shoould be done tonight

Ok here we go with Kennyspecs VE table tuning how to.

The VE table and the MAF are both used to calculate fueling and they both have a “error” in them. We need to eliminate the error and get the car to shoot for a 14.7:1 AFR during light throttle and cruzing. We do now know how much error the VE table or the MAF has so we will first start out by eliminating the error out of the VE table. And by error I am meaning lean or rich.

Step 1 Fail the MAF.

Open up Hptuners and set the “Maf fail High” to 0
Then set the P0103 code to “MIL on first error”
If done correctly you should now have a check engine light on when you start your car.








Step 2 Set up the car for open loop.

Under fuel control OL &CL TAB there are 3 tables that need to be changed. They are adders/multipliers for fuel. We want to change them all to 1 cause the less multipliers and adders you have the easier tuning will be.
The three tabs are

Gas (Gear)
Gas (P/N)
IVT Gain

The entire table does not need to be changed. Just change them where I have highlighted.





Turn off DFCO



Step 3 PE table.

The PE table is a multiplier for fuel when the car is under high load/WOT. It determines the AFR that you get during WOT. You set the PE table to the right multiplier to give you the desiered AFR that you want at WOT and then LEAVE THE TABLE ALONE!!! You then adjust the VE table or MAF table to obtain the correct AFR. The equation for it is
14.7/”EQ Ratio vs. RPM” = AFR at WOT

So lets say that I want a 11.9 AFR at WOT so the value in the “EQ Ratio vs. RPM should be 14.7/ x = 11.9 x = 1.235

So I then set the EQ ratio vs. Rpm to 1.235 across the entire range.

(disclaimer: I am not saying that a 11.9 AFR is safe and should be used but it is what I use with my meth injection)


I did not like how in the gmstg2 tune the car didn’t go into PE mode until above 4800 rpm so I changed some things.

PE Enable MAP to 115kpa ~ 3 psi
PE delay RPM 0
PE table TPS (see table below)
Enrichment rate 1
Piston Protection 8000rpm

Now the car will go into PE mode regardless of rpm. Anytime you are over 3psi the car will richen up and go into PE mode.




Step 4 Turn off COT



Finally its time to go drive around and tune the car!!!!

So I assume that you have a WB 02 set up to log into HPtuners. Also you have to have a AFR% error histogram set up in HPtuners. It should log error based on your wideband. NOT based on LTFT or STFT.

Start up car and wait till it has reached operating temp 180* F

Start logging with hp tuners. hit the reset fuel trim button.

Drive around nicely on a open highway hitting as many cells as much as possible. Vary the rpm and map as slowly as possible. Try to stay out of PE mode. (stay below 4psi) and I don’t bother tuning anything above 4000rpm as I don’t do any “nice” driving above 4000 rpm. These are the cells that you want to “hit”



Once you have all the cells hit at least 20 times copy and paste by % error into the VE table. Start the car up again and restart the process. Drive around on the open highway again for about 5 mins before starting to log again. The reason for this is when you shut the car off to flash the new tune the car heatsoaks. This will throw off the tune. Driving around for the 5 mins just gets rid of the heatsoak. Now when you copy and paste by % error into the VE table you should have less error than last time. Now as you get closer to 0% error you should see that the WB gauge is closer and closer to 14.7 at part throttle driving. When you now paste the error in the VE table paste by % error half option. This just prevents you from going to far and overshooting the error. you will never get to 0% error so dont bother wasting your time. you should be able to get +-4 though.

There ya go. Your car should be now tuned in open loop. once done this its time to tune
the PE mode in open loop. To tune the PE mode is the same as tuning part throttle but now you are tuning at WOT. HAve fun with this. just watch out for knock and keep a eye on your AFR.next comes the maf. that will be in part 3 of the series.

Originally Posted by foff667

Very cool! Has someone posted this on our forum yet?

Originally Posted by Witt

Also disable DFCO by maxxing out all the DFCO tables. When the car is in DFCO the commanded AFR will stick at 14.7-1 while the wideband will be lean giving you a false positive error. These cars seem to have horrible throttle response while in SD with DFCO enabled, it should fix that.

After maxxing out the values log a status bit for DFCO to be 100% sure that it is disabled.

Originally Posted by ssnipes

DFCO= ?
SD = ?

thanks

Originally Posted by Jackalope

And all that but noone can get the 2.4 right? Well without spending $300+ at tune Time that is.

I wish we had a car that could be figured out.

Originally Posted by Witt

What can't you figure out?

Originally Posted by Jackalope

Man don't get me started! I went thru Steve, DOC, and 2 different tuning shops and the same thing happened every time, my car would end up on a roll back headed to the dealership to get flashed back stock.

I got everything I was told I needed for the 2.4 tune, the injectors, the harness and had people that know what they're doing and each time..... "um...I don't know what happened but your car won't even start now. I can't even get your stock file to re-load so you'll have to go back to the dealership to get it fixed, sorry."

After almost 4 MONTHS of trying to get the car to be tuned I gave up. Its NOT worth the headaches. When I save up I'm driving to Jersey to have Tune Time do my car.

Nothing against HPT or any of the poor guys who have tried to do my car but after that long it gets old.

Originally Posted by CHARGDSS

So pretty much just change the enable RPM and Temp so they can't be hit?

Originally Posted by Witt

Oh I thought it was something specific to all models that you couldn't figure out. Yours sounds like a defective part perhaps. I've reflashed 2.4s with no problem, including adding forced induction to one.

Originally Posted by Jackalope

Nahhh, I had it to like 3 different dealers and it would always take the stock file back from them, its just the HPT stuff would never work right. Maybe they all just don't know what you do man. Hey your close by, what do you think you could do for me? And for how much?

Originally Posted by Jackalope

Man don't get me started! I went thru Steve, DOC, and 2 different tuning shops and the same thing happened every time, my car would end up on a roll back headed to the dealership to get flashed back stock.

I got everything I was told I needed for the 2.4 tune, the injectors, the harness and had people that know what they're doing and each time..... "um...I don't know what happened but your car won't even start now. I can't even get your stock file to re-load so you'll have to go back to the dealership to get it fixed, sorry."

After almost 4 MONTHS of trying to get the car to be tuned I gave up. Its NOT worth the headaches. When I save up I'm driving to Jersey to have Tune Time do my car.

Nothing against HPT or any of the poor guys who have tried to do my car but after that long it gets old.

Originally Posted by Jackalope

And all that but noone can get the 2.4 right? Well without spending $300+ at tune Time that is.

I wish we had a car that could be figured out.

Originally Posted by Jackalope

Nahhh, I had it to like 3 different dealers and it would always take the stock file back from them, its just the HPT stuff would never work right. Maybe they all just don't know what you do man. Hey your close by, what do you think you could do for me? And for how much?

Originally Posted by Psykostevo

FYI this goes for almost any car not just Cobalts, the menus in HPT may differ from car to car but the science is still the same.

Originally Posted by Psykostevo

I don't know what DOC did to your car with my tune, but is obvious he had no clue what he was doing with it. It was never installed properly, and to date all of the 2.4L I have tuned in person run just fine.

I knew there was a big problem with who ever flashed it when you told me you needed a Case Learn after an HPTuners flash :-(

Originally Posted by BennyHHR

In defense of DOC, who unfortunatly ran into issues with the 2.0 and 2.4 ECMs being in a completely different data bus, and in answer to Jackalope who hasn't been able to get a good tune....

Jack, you're lucky that DOC wasn't able to write the Psykostevo tune to your car! Last weekend, I did a scan on one of his tunes and if anyone can call incorrectly scaled injectors, +10% AFR errors, 6* KR and < 10 PE AFR a "tune"....