Trouble tuning 07 Cobalt SS

[lwrs10]

This is my first large injector boosted tuning experience, and I am having a few issues I hope someone can help me with.

Car is a 2007 Cobalt SS LSJ with a 2.8, ported blower, Siemens Deka 60's, and a CAI and exhaust.

First, the idle trims vary alot. Sometimes they are really rich, sometimes they are lean. And on de-accel, trims go super lean. It is not a MAF issue because it is the same box in the MAF table that shows lean on de-accel and rich at idle. I have tried to tweak the short pulse adder tables to no avail. The problem seems to be anything under 1.2ms pulse width.


Second, after the injector change, I have a single cyl missfire at idle only. I think I have a bad injector, but am too new at this to tell.


I attached my tune and a log file. The tune is still very rough because I want to get the injector problems worked out first before I trim it in perfect.

Help me out please....pulling my hair out.

new60tune2.hpt

wbscan.hpl

[GM COBALT SC SS]

your trims are going to go lean on decel until you tune for it, as you have dfco off. and if you do tune for it, then it can cause a very rich idle. i see that you have your dynamic airflow set to upper rpms. that will help with this. all i can suggest you to do about it is tune as much as you can with dfco off, like you have it. ve and maf. then tune the idle under ve and maf. and on your daily tune, turn dfco back on.

i dont really know about the misfires though.

[lwrs10]

posted right as you did....

that makes sense abut the DFCO.

[GM COBALT SC SS]

I ran into a similar issue a little while back. I noticed that while tuning with dfco off, it would go really lean during decel like you stated. Stfts at +30 or so. Almost like I never turned dfco off. So I stopped the car, made sure dfco was off and reloaded the tune. It was still going lean so I tuned for it, only cruising, no idle.

Then when I got done and finally let it idle, it was running -15 ish on stfts. I guess it's just best to find a happy medium.

Make sure you reset your fuel trims each time you log as well. I've run into some trouble forgetting to do that lol

[noorjSS]

I thought full lean on decel was supposed to happen on a MAF only tune, even with dfco disabled.

[GM COBALT SC SS]

It does, but I'm running a maf, ve blend to help with that. That's what I was saying, if you tune the maf at full decel, your gonna be super rich at idle. I have a hard time getting my point across though lol.

[noorjSS]

Oh alright, sorry I didn't understand. What is the benefit to turning off dfco/not having full lean at coast down?

[GM COBALT SC SS]

Ah its not a big deal. I just leave it off for tuning to try to get more tuning data. But leave it on for daily driving

[lwrs10]

figured it out. Besides the DFCO thing, these Siemens suck. I am trying to use them below their advertised minimum pulse width. They are rated for 1.5ms minimum linear, and turn on time is 1.14ms at 14 volts. My idle is right about 1ms, so below where these are even supposed to work.

Sound about right?

[GM COBALT SC SS]

im guessing the tune your running is from ottp with a stage kit? i have a similar tune, but i never ran it. that is because there is an injector data sheet floating around on here and the rlf that has good parameters for 60s, which i am running as well. i have never learned how to tune injectors and do not really care to try, as the injector data sheet has been really good to me. it has parameters for lucas 42s, siemens 60s and 80s. thats probably all ill ever need. ill look for the link for it.

but im pretty sure omega put it together. and if you want to give it a try, maybe youll have better luck with it as opposed to the ott tune

[GM COBALT SC SS]

http://www.4shared.com/file/iMEZr2wG/Spreadsheet.html

that is the spreadsheet

[lwrs10]

im guessing the tune your running is from ottp with a stage kit? i have a similar tune, but i never ran it. that is because there is an injector data sheet floating around on here and the rlf that has good parameters for 60s, which i am running as well. i have never learned how to tune injectors and do not really care to try, as the injector data sheet has been really good to me. it has parameters for lucas 42s, siemens 60s and 80s. thats probably all ill ever need. ill look for the link for it.

but im pretty sure omega put it together. and if you want to give it a try, maybe youll have better luck with it as opposed to the ott tune

this is not an OTTP tune at all. It is my tune, with injector values and spark tables from the how to here modified for my car.

[GM COBALT SC SS]

oh the sjchafer how to? i guess ott uses the same fueling values.

if you havent already, i would check out the rlf how tos. they are very helpful for tuning the lsj

and if you are having injector issues, i hope it can get resolved. i saw the misfires on cyl 2. i cant say ive had that happen with my 60s

[laser_racer]

You might have a injector seal leaking on that cylinder that will cause missfires in one cylinder. When you do tuning you have to make sure you don't try to slow down against the gear. Put it in neutral so there won't be any really odd fuel trims weather the deaccel is on or not. I can't see the tune from work but if the dynamic isn't set like 300 over 200 your not on 100% maf.