Rich Idle and P0172/P0175

[Robofuzz]

I'm pretty new to tuning and just recently bought HP Tuners.

First, a little about my car:
2005 GTO, stock LS2 bottom end, L92 heads (milled .030), ported L76 intake, Livernois L92 Stage 2 Cam (230/236 114 LSA), long tubes, high flow cats. It's got an over the radiator CAI with an LS3 MAF in it. I had it tuned at a shop a pretty long way away, and then discovered I had a bad vacuum leak around the new MAF. I fixed the leak and, because of the change in MAF airflow, had to fix the MAF table by logging and tweaking it using some instructions in threads I found here.

I've got everything pretty well dialed in with the exception of the idle. The car seems to idle OK, except that it smells really rich at idle, and throws P0172 and P0175 codes when it idles for a couple of minutes after it's warmed up. My LTFTs go up to -12.5 or higher at idle. It does not throw the codes if I clear the codes and then immediately drive. Only at idle does it seem to throw the codes.

I'm not sure what to log and what to tweak to dial in the idle. I need a starting place so I am not changing the wrong things. I've seen some of the threads on idle tuning, but I'm confused about where to start, what to log, and what to change. I think it's mainly an airflow issue because of the MAF leak I mentioned above.

I am attaching my current tune. Any help is appreciated! I feel like I'm pretty close to having this dialed in.

[c.u]

What size inj are you using and brand. Do you have a wideband. You are running maf only and it has some big numbers in it. I would put a stock low maf table Back in it to start with. How are you tuning the maf right now.

[Robofuzz]

They're stock LS3 injectors. As for the MAF, it is an LS3 card style MAF. The car won't even start if I put the LS2 MAF table back in. I do not have a wideband. I tuned the MAF using a histogram setting I found here. I'm not at my tuning computer so I'm not sure what was logged. However, tuning the MAF that way got my fuel trims all in line and got rid of a bucking problem I had. Now I need to fix the idle.

I just read I should reduce the VE table in the idle range.

[c.u]

The IFR table Numbers look low for ls3 inj whitch can make it run rich. Need to tune the maf then shut the maf down and then tune ve. At this point you are running maf only. I did not say to use the ls2 low maf table. You will need a WB for wot tuning. From what you said i take it your using STFT or LTFT for tuning right now.

[Robofuzz]

I tuned the MAF table using histograms 4 and 5 in this config. As I said, everything seems pretty well dialed in and gas mileage is up, surging at cruise is gone, and driveability is very good.

Can I tune the idle now to be less rich without buying a WB and upgrading HP Tuners to Pro?

[c.u]

It looks like when it was tuned that it had some unmetter air going on. Insted of finding it thay change the IFR table to richen it up this is not the way to take care of it. Put thes numbers in like the Screen shot. Yes you can tune with STFT for idle and part thorttle. You do need to disable LTFT,cot,pe and ve witch it is right now diable in the tune. You can get to around 3 to 4% tuning like this. For WOT you do need a wideband. If you do a search in vcm suite enhaced IO you find how to hook it up with out the HP pro.

[Robofuzz]

Oops - I posted the tune I was using when logging to correct the MAF table. Attached is the full tune with the corrected MAF table.

I will go back and reset the IFR to what you posted and start over getting everything dialed in. Thanks so much for the help. I will make getting a wideband a priority.