LNF, Cobalt SS, rough idle after cat heating disabled

[TurboCobalt]

hello all,
I'm a noob and i need help.
I have a 2008 Cobalt SS with a Injen upper charge pipe, 3bar sensors, and a tune that is mostly stock + GMPP changes (what we can see at least).

I want to turn off Cat heating because it is noisy, a bit too agressive for a cold block (maybe), and a great opportunity to learn engines while im trying to fix this.

If i just turn off the Enable/Disable cal it ran very poorly, chasing rpm, oscillating throttle, spark time and cam timing.
I think that even if i disable "cat heating" it still uses the "cat heating" cam tables, so i copied the idle warm values and put them in the "cat heating cam" tables, so -6 for exhaust +10 for intake. Now the cams are parked, and it cold-idles much better, stopped hunting the idle but i think i can do better.
I also raised the idle RPM at low ECT, that helped but it's not quite perfect.

I think it would run better with more spark advance. (it now sits around 3 to 7 deg timing) But i can't figure out how to advance timing during idle.
Cam tables, optimum spark tables, optimum torque tables are all GMPP values, and spark tables state 20 deg in this load area, however the car runs at about 3-5 or so. So i know there must be more to it than simple putting a higher value in the spark tables.

I've read a lot of threads, and dont think i came across the answer, unless it was staring me in the face and i didn't realize it. Noticed a username "gmtech..." that had a lot of advance at idle and low load, I can't think for the life of me how he got there.

Any advice is greatly appreciated, please help a new guy out and i think i might be added value once i catch up with you guys.
Thanks in advance.

[T-Man]

Read up on the recent optimum spark thread. Will help you learn how to bump idle timing that you're looking for.

Also, you'll want to toy around with the DALs in the idle area's with and without the AC on so that you can keep her happy. Good luck man!

[MikeM173]

Turbo I will tell you it is rough. Very possible though. I have mine turned off and timing is around 18-20 and idles smooth. I also put it on my customers cars who are catless. It is a pain figuring it out and it takes a while to master the timing tables including op spark. It is a balance between DALs, Cams, Spark, Op spark, and Idle. As well as having that locked in perfectly you need to have your car running optimum mechanically and have your MAF dialed in. My intake was actually causing issues with the MAF and I opted for Mafless to fix it. A few other things mechanically can cause issues as well when tring to perfect idle. If I left anything out I'll update later. Couple tips I can let you in on are ensure all of your cam tables have the cams parked. Some times people miss a table and that can cause a huge issue. Also remember that the timing tables will not give what they show in areas. If I put 40deg timing on spark and 40deg in op spark in the same cells it will not sit at 40deg. You'll notice it'll sit lower. Where you see that it hits what the table is set to is higher loads such as WOT. Look into that some more and play with it to understand what it is I'm talking about. A lot of Tuners before (Not sure about now and I don't tend to try and look at tuners tunes) wouldn't even turn off cat disable because they couldn't get it to idle correctly. I had a rough time learning it myself. I had some pointers like I'm trying to give to you but most of it was put numbers in and figure it out. I will say tuning the rest of the ECU was easier for me then idle was unfortunately. Hopefully you have better luck.

[codename Bil Doe]

^What they said.

I have it off for the catted and catless cars.

1) Make sure all four idle tables are in the park position for your intake and exhaust cams

2) Make sure all four timing tables are the same for your intake and exhaust cams

3) Read up on optimum spark and timing table threads. This will fix your idle issues. You won't have to touch DAL's to fix them, but MikeM nailed it with the timing requested versus actual timing.

4) MAF has a huge effect on idle performance. You'll have to get it dialed in after fixing the timing. Then, go back and start turning on AC and other accessories while parked to get it more dialed. CCSOB discussed it somewhere in one of his help threads.

Both of my cars fire up smooth cold and immediately idle ~16-18°. It's all just taking your time. Optimum Spark tables are critical for proper idle timing. MAF will affect smoothness once you get the timing in the right window.

[MikeM173]

Bill is correct on the DALs. Mine are a tad different at idle as is his but I can tell you that playing with the DALs at idle will affect it. Mine is at 20deg but that is simply because of how my setup is. On my customers cars they are 16-18 unless they have mechanical issues. I would worry more about learning the spark and op spark tables prior to doing this though. Just my recommendation. By that time you'll have a better understanding of what is going on and it should help. Then it is just playing with it until you get it nailed. I highly recommend that when you figure it out you don't go posting your tables for it. I say this for two reasons. 1: people will definately steal them. 2: (this is by far more important then #1) People will just copy and still not understand the affects of what they are doing or why. When messing with stuff in the torque tables it is by far a lot better for people to have an understanding of what they are doing so they do not screw things up. Read the warnings on op spark and you'll understand why I mention this.

[MikeM173]

Oh I forgot another table that messes with idle.

Optimum Torque I think that is what it is called. I am at work and don't have my computer on me. Changing the values in that will affect it as well so remember that when making changes to that table. That should not deter you from changing it just realize that you will have to make changes to other tables when you do.

[cobaltssoverbooster]

gmtech went over this a before i came back to it. its a fine balance between dals/timing tables/optimum spark and the maf must be re-calibrated after every change to account for its complete effect. as gmtech found out idle timing showed to be smoothest between 18-20* advance. i also watch idle vacuum values to see if i'm dropping vacuum or holding it steady (helps with aftermarket blow off valves since the lnf requires the lower pressure springs to work properly every bit helps)

the writ-up from Bill on optispark will help a lot

[TurboCobalt]

Thank you all for your help.
I will be out-of-state for 2 weeks, but i'm looking forward to figuring this out after, and i'll report my results.