06 Cobalt SS 2.4LE5 SC build.

[JMsquared]

Just click on Go Advanced next to Post Quick Reply, then click Manage Attachments, then another window will come up and click Add Files, then you have to get your tune from whatever file or if it is on your desktop and then just click on the file you want. It will then be added to Attachments, just hit Insert Online, then Submit Reply. And that's how you post your tune file or scan log or any of type of file that is supported.

Im going to try to post the tune, and possibly a log file!Cobalt 1-21-15 10% hi maf, reset PE.hptMaxwells config.cfg

The clutch holds, and we installed and LSD into the F23 transaxle. I need help to make a decision...
the pulsewidth at idle is .8-1.3ms while the pulsewidth at 5900-6000 is 18-21ms (DC = 85-100%).
At 6000 the AFR climbs to 13.5, then I get Knock retard.
I checked fuel flow .92 gpm @voltage 12.8volts and 1.04 gpm @ 14.8volts.
I don't know which way to go...variable volt fuel pump controller, or some type of regulator in the tank.
Any thoughts...
BTW...this is a hoot to drive!

[MarkTucker]

So it is not allowing me to open the log that you posted, but do you have the stock fuel pressure regulator? If so you will need to get a Boost reference fuel pressure regulator. ZZP sells the setup for your LE5 car. They call it their Boost Reference Fuel Pressure System(BRFPS). That will help alot, cause with your fuel pressure staying at a low pressure like your stock setup is designed to then you won't have the fuel for when you go into boost.

[Spawne32]

For the oil pressure, go to Engine Diag/General/Oil Press/Temp. You can change the settings for the oil pressure sensor or switch. Which ever one you have installed. And for IAT2 make sure the inputs are correct for the table for IAT2 under Engine Diag/Airflow/IAT Sensor. Also you can go into Engine Diag/DTC's and you can enable the codes for the new sensors.

are you saying that we can switch out the oil pressure switch for an actual sensor and get an accurate readout in VCM scanner that easily?

[MarkTucker]

You can install a oil pressure sending unit, would have to wire the sensor correctly into the ECU correctly and then you would have to change the setup in the editor to get a correct reading into the scanner of oil pressure. But at that point, I would just suggest installing a aftermarket oil pressure gauge.

[JMsquared]

So it is not allowing me to open the log that you posted, but do you have the stock fuel pressure regulator? If so you will need to get a Boost reference fuel pressure regulator. ZZP sells the setup for your LE5 car. They call it their Boost Reference Fuel Pressure System(BRFPS). That will help alot, cause with your fuel pressure staying at a low pressure like your stock setup is designed to then you won't have the fuel for when you go into boost.

Thanks, Ive been looking at that...have not pulled the trigger on it yet.
Im getting a lot of buzz to use the split spray injector from Bosch to solve the problem...supposed to be faster off the seat. The injectors are slightly less than the BRFPRS...tough decision.

[MarkTucker]

You are going to need the BRFPRS. If you decide to go with a larger injector, that will fix your issue as well but even with a larger injector you will be pushing them to a higher duty cycle than needed for the power output. With a BRFPRS, it will be able to up the fuel pressure for when in boost so that the injectors don't have to work so hard to push the fuel into a cylinder with boost pressure. So I would strongly suggest the BRFPRS. Save up for injectors for when you do actually need them, for when you want to go more power.

[JMsquared]

You are going to need the BRFPRS. If you decide to go with a larger injector, that will fix your issue as well but even with a larger injector you will be pushing them to a higher duty cycle than needed for the power output. With a BRFPRS, it will be able to up the fuel pressure for when in boost so that the injectors don't have to work so hard to push the fuel into a cylinder with boost pressure. So I would strongly suggest the BRFPRS. Save up for injectors for when you do actually need them, for when you want to go more power.

Yea...I came to that realization today...both parts contribute to better cleaner fuel delivery...so here we go.
What is max pressure typically with 12psi boost?
Has any body had any success with fuel pump voltage boosters?
I'm going to be installing the AEM fuel pump anyway, due to age.
Thanks, I'll work on posting the tune again tomorrow.

[MarkTucker]

Well for easiest tuning and best on fuel pump and injectors is the BRFPRS and with that you will get a 1:1 increase. So for every psi of boost you will gain 1 psi of fuel pressure to offset everything as if there was not boost fighting back against the incoming fuel delivery. I have not use a fuel booster pump on a cobalt. I using try to stay away from installing them on any application but sometimes when alot of aftermarket parts were available for a certain vehicle. I have installed them, and they work okay. But a upgraded fuel pump is definitely will be worth it. But it answer your question about what is max pressure for 12 psi. Just take your stock fuel pressure and add 12. And that is what fuel pressure you want when you are at 12 psi of boost, but is not needed that high at idle and vacuum situations.

[cobaltssoverbooster]

if you don't use a fuel pressure regulator with a vacuum reference then you will be spending a ton of time in the injector flow bench shop to get the required values to make it run smoothly. running the boost reference makes the tables linear so you have half the values to adjust. this way you flow bench the injectors once collecting the simple data, fuel flow per pulse, voltage offset multiplier, and short pulse correction. what makes this really hard and expensive is getting these tests done numerous times for the pressure between the manifold and fuel rail constantly changing. the difference between the two is called Delta Pressure, and is an axis on one of the biggest injector tables in the ecu. Listen to mark and spend the money to take the easy way out on the tuning side.

[JMsquared]

if you don't use a fuel pressure regulator with a vacuum reference then you will be spending a ton of time in the injector flow bench shop to get the required values to make it run smoothly. running the boost reference makes the tables linear so you have half the values to adjust. this way you flow bench the injectors once collecting the simple data, fuel flow per pulse, voltage offset multiplier, and short pulse correction. what makes this really hard and expensive is getting these tests done numerous times for the pressure between the manifold and fuel rail constantly changing. the difference between the two is called Delta Pressure, and is an axis on one of the biggest injector tables in the ecu. Listen to mark and spend the money to take the easy way out on the tuning side.

Thanks for the feedback, Im getting the stuff gathered up, Fuel pump, Regulator, injectors... Then the tuning part.
so I am appreciating the help.

[JMsquared]

Well Mark, Its been a year since the last post for the Cobalt...( I couldn't find the post..lol) I did as you and cobaltssoverbooster recommended, I installed the fuel pump and mounted a boost referenced pressure regulator behind the fuel tank. I reset IFR tables...Fueling was instantly more accurate as indicated by the WB. We tuned MAF only on the dyno, been driving it every day since. I've since been learning the Virtual VE portion of the tune. Two things that are problematic; ECM is limiting boost at 3.5 psi and 2) LTFT keeps adjusting fuel back to 1.0 lambda in the boosted region...anyway I just found the post again, so Im updating it. Thanks for your input. Ive posted tune and config\layout files for HPT2.24 and 3.023. Feel free to comment on it.