2007 Corvette A6 Lean After Catback Addition

[Ancient8989]

I had the car tuned with only the x pipe on and the AFR's were great at idle and cruising speeds, 14.7-15.5. I added the rest of the exhaust system and now it idles anywhere from 15-17 AFR and regular driving is 15-16 AFR. WOT is still 12-13 AFR. I'm not really comfortable with the light to mid throttle running that lean after just adding some mufflers. I went through and tightened every clamp on the system and no change. I know the cam is aggressive so its going to show leaner at idle, but this was kind of a dramatic change to both modes. Otherwise, the car acts fine. Should I worry? I don't want to take the car back to the shop for it to sit for two weeks & cost me $$$ for the tuner to revise the tune. I have a MPVI 2 and the drive to learn to do it myself.

Mods:

BTR Stage 4 N/A cam and springs
FAST 57lb Injectors
CAI
FTI 3x 3600 Stall
Walbro 450
Melling High Pressure Oil Pump
1-7/8 Long Tubes
Speed Engineering xpipe kit and catback system
AEM UEGO Wideband

I have uploaded my tune and I can't figure out what he used to tune, whether its open/closed loop tuning. All I want to do is add a little fuel to richen the AFR's slightly during idle and light to mild throttle. Where should I start? What is being used to tune? Thanks in advance!

[5FDP]

Can you provide a data log too?

Closed loop operating in the tune file anyway is still all active. I've never seen a cat-back or muffler back exhaust make a engine just run lean for no reason.

[cadillactech]

So you had no mufflers until after the tune was done? Where was the wide band installed for the tuning done? Did he use the same wide band you have installed now?

If you look at your tune, you are on a MAF only based airflow model. VVE is stock. Not the most thorough calibration but many people do it this way. It takes time on a load bearing dyno to dial in the VVE and most do not have the skill or equipment to properly calibrate it, nor do most people want to pay the money for it to be done either.

Does it shift smoothly? How is the drive ability during part throttle? If it is ok to you then I wouldn't worry about it not having the VVE calibrated.

That being said, the addition of the mufflers may have changed the airflow through the engine enough to change your running AFR readings but I can't say for sure. I am more curious about the wide band placement during tuning versus now.

You need to modify the MAF curve in the areas that are too lean for your liking.

[01SLPSSM6]

So was it tuned with just the x-pipe on and no exhaust after that? For starters, their is no injector data for FAST injectors and the data in your file is definitely not correct. I would recommend getting a set of flow matched injectors that have actual data or even a set of 42LB HR LS3 Injectors. Getting the MAF AND VVE airflow models properly calibrated is the most important part of the calibration, if the injector data is incorrect, the calibration will never be correct. To answer your question, if you want to try and correct for a lean condition, you can modify the MAF curve. Also are you still running the stock fuel pressure regulator with the 450 lph fuel pump?

[cadillactech]

So was it tuned with just the x-pipe on and no exhaust after that? For starters, their is no injector data for FAST injectors and the data in your file is definitely not correct. I would recommend getting a set of flow matched injectors that have actual data or even a set of 42LB HR LS3 Injectors. Getting the MAF AND VVE airflow models properly calibrated is the most important part of the calibration, if the injector data is incorrect, the calibration will never be correct. To answer your question, if you want to try and correct for a lean condition, you can modify the MAF curve. Also are you still running the stock fuel pressure regulator with the 450 lph fuel pump?

I would take his advice as well if you want to start going through your set up and making things right. Get some injectors with data so when you start modifying whatever airflow model you use that the injector error is not baked into the calibration because it makes for chasing your tail.

[Ancient8989]

I am still running the stock fpr. I went ahead and bought new ls3 injectors. My wideband is in the xpipe not sure if he added his own sniffer. Car drives fine no bucking or surging really. I'd like to get the car driving better for the time being. Where do I adjust the curve?

[01SLPSSM6]

Airflow-General- MAF Calibration Low Freq/High Freq.

[kevin87turbot]

I am still running the stock fpr. I went ahead and bought new ls3 injectors. My wideband is in the xpipe not sure if he added his own sniffer. Car drives fine no bucking or surging really. I'd like to get the car driving better for the time being. Where do I adjust the curve?

Whereabouts in the X-pipe is the wideband located?

[Ancient8989]

The wb is in the drivers side bank before it merges into the x

[cadillactech]

That should be an ok location. Did you get the new injectors installed?

[Ancient8989]

That should be an ok location. Did you get the new injectors installed?

They come Thursday or Friday. I'll get back to you guys when I install and put in the data.

[Ancient8989]

Injectors came. Where can I find the injector data?

[cadillactech]

Best place is the HP Tuners repository, find a LS3 equipped vehicle, like a 2008 Corvette and download. Then copy and paste all injector data.

[01SLPSSM6]

Stock 2008 LS3 Corvette file attached.