2014 Corvette Grand Sport Closed Loop Issue after startup

[Musky@RG]

I have a customer with a 2014 Corvette GS which has an issue I'm unable to figure out.
Only Mods are: AFE intake, Long Tube Headers and mid pipe (no secondary o2 sensors), LT4 injectors and LT4 high pressure fuel pump

Firstly, the LT4 injectors and pump were just recently installed but the issue was happening before as well. After startup when closed loop kicks in the fuel trims start going negative all the way to -25% which actually makes it run too lean and it starts idling really rough. After about a min and half of run time it starts to clear up as the trims go back to zero. When I disable closed loop the car runs way better and doesn't do it and drives ok, but still a little rougher than I'd like. It also has some codes that pop up which I will post a screed shot of. The tune file and datalog are attached as well.

20240206_100957.jpg

[Alvin]

There is one table you can't change on a '14 when doing LT4 injectors. I can't remember off the top of my head but if you search for 2014 and LT4 injectors on this site you should find it. It's come up a few times.

[GHuggins]

Although the missing table for the injectors may be an issue, it won't cause what you're seeing especially since it was there before them. Problem is what's been done to the car.

You see, there's one test in particular that causes this very problem mainly on cars and very select OS trucks. It's the post O2 test. It will actually cause them to get stuck full lean until the throttle is either blipped or the car is shutoff and restarted. You or rather the owner have two choices. Install the post O2's and kill the cat lightoff, which will be your easiest or set all of the OBD2 and test settings accordingly for what's been done. AND just to clarify that's if it's not on the road anymore as this is all illegal I don't think people realize or know how many settings have to be changed just for removing one component for those offroad buggy trips..... There's about 11 or 12 for removing just the post O2's. SO, again, it might be in your best interest to reinstall cats and o2's then go from there.

[Musky@RG]

There is one table you can't change on a '14 when doing LT4 injectors. I can't remember off the top of my head but if you search for 2014 and LT4 injectors on this site you should find it. It's come up a few times.

Yes I know the table you're talking about, it's all good. Thanks for the reply

[Musky@RG]

Although the missing table for the injectors may be an issue, it won't cause what you're seeing especially since it was there before them. Problem is what's been done to the car.

You see, there's one test in particular that causes this very problem mainly on cars and very select OS trucks. It's the post O2 test. It will actually cause them to get stuck full lean until the throttle is either blipped or the car is shutoff and restarted. You or rather the owner have two choices. Install the post O2's and kill the cat lightoff, which will be your easiest or set all of the OBD2 and test settings accordingly for what's been done. AND just to clarify that's if it's not on the road anymore as this is all illegal I don't think people realize or know how many settings have to be changed just for removing one component for those offroad buggy trips..... There's about 11 or 12 for removing just the post O2's. SO, again, it might be in your best interest to reinstall cats and o2's then go from there.

Thanks for the reply. I had a hunch it might be something like this, that's why I mentioned the car had no secondary o2's. Hopefully the customer still has them or I will be ordering up some new ones.

[96GS007]

Is there any other reason for this to occur? Mine is a little different in that sometimes the LTFTs go crazy rich (ie -15 sort of thing) and then over 5-10 minutes they correct and get back to normal. The next time I start the car....2 minutes later, overnight, whatever...they'll be crazy lean (ie +15 sort of thing) and then correct themselves. Sometimes....no issue at all. Cold (ie after sitting overnight) or warm, all is good. It's consistent behavior when I look at the fuel trims vs the MAF and vs the VVE table.

I have everything turned off I can find...it's a track day car...but this has me scratching my head. I tried doing a full write vs just the calibration to no avail.

Screenshot 2024-02-12 203857 Run 1.jpgScreenshot 2024-02-12 203646 Run 2.jpg

[GHuggins]

Is there any other reason for this to occur? Mine is a little different in that sometimes the LTFTs go crazy rich (ie -15 sort of thing) and then over 5-10 minutes they correct and get back to normal. The next time I start the car....2 minutes later, overnight, whatever...they'll be crazy lean (ie +15 sort of thing) and then correct themselves. Sometimes....no issue at all. Cold (ie after sitting overnight) or warm, all is good. It's consistent behavior when I look at the fuel trims vs the MAF and vs the VVE table.

I have everything turned off I can find...it's a track day car...but this has me scratching my head. I tried doing a full write vs just the calibration to no avail.

Screenshot 2024-02-12 203857 Run 1.jpgScreenshot 2024-02-12 203646 Run 2.jpg

Most likely your fueling wasn't dialed in at temp and/or the density table is wrong. Don't remember if your density table was changed in another one of your post as a test or not. If it was just put it back to stock and dial your fueling in with a coolant temp > 185 F and inj tip temp > 60 AND inj tip temp < 80. You can hone in on it better via the temperature settings for the filter. Once it's dialed in there you'll still need to correct it via the density table for changing temps. If you don't want to have to mess with your torque model anymore you can look at the logs where you dialed in your fueling, figure out the tip temp range it was dialed in at and leave that area as is then dial the rest of the temps in around that. The stock density table will get it really close for all the temps, but you'll still have to rework the torque model and the colder temps of the density table to get everything right. Depends on which route you want to go.

[96GS007]

Most likely your fueling wasn't dialed in at temp and/or the density table is wrong. Don't remember if your density table was changed in another one of your post as a test or not. If it was just put it back to stock and dial your fueling in with a coolant temp > 185 F and inj tip temp > 60 AND inj tip temp < 80. You can hone in on it better via the temperature settings for the filter. Once it's dialed in there you'll still need to correct it via the density table for changing temps. If you don't want to have to mess with your torque model anymore you can look at the logs where you dialed in your fueling, figure out the tip temp range it was dialed in at and leave that area as is then dial the rest of the temps in around that. The stock density table will get it really close for all the temps, but you'll still have to rework the torque model and the colder temps of the density table to get everything right. Depends on which route you want to go.

Thank you as always! All the temp correction "stuff" is enabled and stock. I'm looking at items under "Airflow > Speed Density > Corrections". I don't have tip temp logged but just looking at items with the coolant temp >185 and the number of cell hits >1000 certainly smooths things out. These are 30min+ drives.

I'm so darn close to having that last half of a percent of driveability solved that I guess I'm overthinking things and as I get more and more familiar with what I'm doing, I'm sure I'm seeing more and more things I likely missed previously.

[GHuggins]

The density table I was referring to is the fuel density table. It's in the injector section and is defined as tip temp and rail pressure as it's axis.

[96GS007]

Ah got it! It's all stock. Never changed any of that