06 CTSV 402 stroker hanging idle after cleaning TB

[snrusnak]

Hello, this is my first post. I bought a 2006 CTS-V with a LS2, it's a 402 stroker (trick flow as cast heads, BTR stage 3 cam, longtubes, fast 92 intake, some other things...) about 6 months ago. I've only put maybe 1000 miles on it, I have been doing some maintenance items to it that needed done. The car basically ran fine, the idle would sometimes hang when the engine was hot like sitting in traffic. But usually short lived and would return to normal, and I could just barely ride the clutch for a second and it would drop the idle to normal (only had to do this a couple times). When it did this the idle would be around 1500-2000rpm.

So I changed the K&N intake for a Volant, and when I did this I cleaned the TB (Stock LS2 TB I believe, 90mm), I cleaned the MAF (stock MAF), and I extended the MAF harness as it wouldn't reach. In hindsight, I wish I wouldn't have cut the stock MAF harness, but oh well now. I don't believe that is my issue, I have good solid connections, but maybe I'm wrong...?

Now the car will start and idle fine all day long, but once the engine temp gets above ~150ish, if you touch the accelerator pedal, the idle hangs around 1500rpm and will not return to normal. If you never touch the accelerator pedal, it idles perfect all day, even with the ECT getting to normal temp ~200. The headers will also start to glow when idling high, I'm assuming this means it's lean, due to the TB letting more air in but maybe the computer not realizing that air is there or something??? So when I see the headers glowing I shut it off. This basically means I can't drive it.

I tried various TB relearn procedures without luck. I've now bought hptuners (MPVI2) to try to help troubleshoot, etc. I have not licensed it yet, just pulled the tune file and did a cold start and warm start log. I tried the "throttle cleaned" button on the VCM tools in Scanner but don't know if it even did anything, when I click it nothing happens. When looking at my warm start log, after I press the accelerator pedal, the accelerator position returns to it's normal idle percentage, but the TPS does not, it hangs higher. I don't believe I have any mechanical issue causing the TB blade to stick, so I'm thinking I have a bad TB (TPS???) or something in the tuning (which I didn't mess with at all) is telling the TB to stay open further.

Anyone have any thoughts or advice? I'd greatly appreciate it. I'm basically brand new to hptuners and basically all tuning, though I have used handheld tuners before and I do have a pretty good understanding of the purpose of all the sensors on the car. I just have never got into details of tuning.

One thought, if the car was tuned with a dirty TB, and now I've cleaned it, could my baseline idle airflow tuning be off now???

Thanks in advance!

[snrusnak]

This is a really old thread, but I'm the OP and came across it again and thought I'd post what the resolution was for my issue. I found a local guy that helped me out, he was more familiar with tuning. We basically arbitrarily removed base idle airflow and startup airflow (in steps) until the car ran good. I think we ended up removing a total of like 40% or 60%, it was a lot. After that, the car ran good and I've been driving it ever since. My only explanation is that when the car was originally tuned it had a dirty TB, and when I then cleaned the TB it gave more air flow due to the dirt buildup that was removed from the TB. I haven't really had any issues since doing this, and it's been almost 2 years.

[kbit]

I'm going through this now, thanks for the update with resolution.

[f00cts]

Can you post the tune file? Just curious since I have an extremely similar setup in my 2006 CTS-V , around 430 cid

[snrusnak]

Sorry been so long, I didn't see your post. Yeah I'll see if I can figure out how to post it. Just FYI, I am just learning all this but looks to me like my long term fuel trims are disabled also (so is speed density). So beware what info you pull from this tune lol. Also note this tune file is during MAF tuning so I have a lot of stuff disabled to keep it out of closed loop.

MAF Step 14.hpt