07 Trailblazer SS, Cam, Longtubes 2 bar SD OS. More advanced questions. LOG/Tune

I have exhausted my knowledge. I am now to the point where I dont even know what to search for and what things to monitor in the scanner.

As the title states, its an 07 Trailblazer SS (e67), with longtubes, an unknown cam, intake, running the 2 bar enhanced SD os.

I have the open loop tuning within 5%, actually more like 2-3% in most places. I have very little knock retard going on and over all it runs well at operating temperature.

The cold start is rough/lean in ambient temps below 50 degrees, it gets rich when warm sitting in traffic, and actually runs better/smoother in open loop than it does in closed loop.

I have logged many hours adjusting the ve table and now have decided that I am chasing my tail. I need to figure out a few things, that i dont believe are VE related.

1. Even when the afr is good at idle (14.6-15.0), the truck doesn't idle smooth, and can actually even puff a little smoke, and exhaust is super fumey.
2. The ignition advance bounces around quite a bit at idle, but is buttery smooth when steady state cruising or accelerating.
3. Is there a way to log what modifiers/advances are active that would be affecting the base ve and timing maps?
4. Is there a way to filter out EQ error during decel?

I have been trying to read up on injection timing. It can be confusing. Most of the how to's suggest that knowing the cam specs helps a great deal when tuning the injection timing, i dont have the cam card. The previous owner does not have it and the installer says he doesnt remember as it was 6 or 7 years ago. I made a few changes to the injection timing tables but it didnt seem to have any effect in either direction.

What do you recommend I log to tune these issues? I have attached a log and a tunefile to this post. I would be more than happy to make fresh logs under any circumstances you recommend with what ever pids logged you suggest.

Thanks guys.

Im trying to get this truck to be a nice family daily and right now I have a pissed off wife and kids who cant stand the smell of daddys car. :banghead:

Attachment 87852
Attachment 87853
Attachment 87854
Attachment 87855

Rich

The idle adaptive spark control, so the under/overspeed tables will be something to look at for idle spark. I'd cut all 6 of those table in half. Because right now it can +/- 20 degrees of spark advance if it thought it needed too.

I tend to make all 3 VE table exactly the same and reset the trims prior to any data logging just in case.

I don't have a stock file here but is the open loop eq ratio always set to 1.00 in every cell on a factory calibration? That could explain the lean start when cold.

I have a stock file I'll look at to compare the open loop eq ratio. I will also try the idle spark changes you suggest.

I knocked some of the over / underspeed idle down a bit and it seemed to make the fluctuation smaller, but it affected my afr quite a bit as well i believe. I will do more tinkering with that. Thanks

Anyone else got any input? In particular to the questions I asked.

I recently switched to the 2 bar OS in my 07 TBSS (kooks, yank 3k stall) and had to make an unexpected change, maybe it could help you- raising min air for idle by 1.75 g/s or about 14 lb/hr for everything (neutral, 1 st gear, all of them). My truck was surging all the time, I was like wtf, but yah maybe raise your min air a bit. Have you adjusted your O2 switchpoints or prop gains at all, or are they still stock? do you have good STFT activity at idle? should see the STFT oscillating for both banks. Sounds like that is working tho


-there are some good threads on here about adjusting O2 sensors on rigs with headers. Two of the tables mentioned in the threads (12470 and 12471, Integrator stuff) are not in the OEM OS for the tbss and they're not in the custom OS, either. I emailed HP Tuners about adding these two tables to the 1250241 Custom os and I think they're going to do it, waiting to hear back.

oh and my VE and MAF are in line, retuned many times. I still think its weird about the min air thing

I also made chopped the adaptive idle corrections in half, it helped smooth things out, as you've seen.

thanks for the tips ill give that a try.