LS2 (CTS-V) Running Lean

[Becker85]

I have been trying to diagnose my lean condition for a couple months on my car, and am about to start shotgunning parts.

Car is stock air intake, and just has catback exhaust.

I got a Diablo Sport tune for fairly cheap and then was working with a Diablo "tuner", I would drive 500 then log info and send it to him, he would modify and send back. ETC....

At the first couple logs I was running a tad rich he had said, then after a couple more logs he said I was extremely lean.

He continued to make richening adjustments on the tune, while I looked over the car.

I have tripple checked all intake hoses, MAF (cleaned), tubing for leaks. I used a SmokePro with 10psi in the brake booster line for 15 minutes to look for intake leaks, nothing.

I had the front pipes welded onto the X-pipe instead of bolted and the exhaust looked over by a shop, and myself.

I have had the "FINAL" tune uploaded on the car for about 2000miles and still I experience +9 - +13 % LTFT's and my STFT's look normal with the O2's. The car has never thrown a code but it makes me nervous getting into WOT being lean, if it is above 85 OAT I will get a bit of pinging as well.

But if I upload any tune (any of the 4 he has made) as soon as I drive the car it feels a lot snappier and will get my michelin pilot sports spinning through first gear. After I log miles on it something changes, and it no longer feels the same.

I have been searching for local HP tuners and have had zero luck, I do not want to pay for a big shop to take my money and kick me back out the door either.

On a side note, when it is cold and I leave the driveway if i give it a bit of load on the accelerator it will stumble just a bit, until it warms up.


Thanks in advance for any suggestions, comments, recommendations

[SultanHassanMasTuning]

Diablo, unfortunately I am experiencing some weird stuff with it as well.

[BMWMD82]

So how do you know you're lean at WOT? Are you logging with a wideband or just making assumptions based on the LTFTs?

If the LTFTs are positive, then the PCM is adding fuel in closed-loop mode. That extra fuel should carry over to WOT operation, at least I'm pretty sure that's how it works. From what I know, the LTFTs won't take away any fuel at WOT, but they will add it if needed. That's the reason many modified cars have the LTFT function turned completely off. They can influence WOT AFR.