Runs Rough - Cold Start - Open loop 6.0ls2 E38

[BML72Nova]

I am at a loss and was hoping I could reach out for ideas, currently when I cold start it takes multiple starts to get the engine warm enough to run as its running unburnt fuel odor is strong. It will run very rough with a low idle and sounds like its misfiring or running on only a few cylinders. See "1_Cold Start - Run to Stall"
If I disconnect the MAF harness it runs much better.

After several tries and the engine is warmed up a but its starts run better, but is still very questionable, any attempt at adding power will not result in the desired revs. "2_Cold Start - Run to Closed Loop"

once it is in closed loop and I restart then the engine runs much smoother.

Any thoughts? Ideas? Thank you in advance!2_Cold Start - Run to Closed Loop.hpl1_Cold Start - Run to Stall.hpl1972 - Nova LS Swap 6.0.hpt

[LS ROB]

Need more information on the engine build and mods, cam, long-tubes, etc. Is this a swap vehicle or 2007 corvette? From the log, this thing looks super lean. Also, add Virtual Volumetric Efficiency to your scanner.

[BML72Nova]

This is a stock engine - LS Swap. Aftermarket intake and headers/exhaust are the only things not stock. 4l80e transmission.
added Virtual Volumetric Efficiency and run.2_Cold Start - Run to Closed Loop v2.hpl

[gtstorey]

Aftermarket intake usually ends up meaning non-stock injectors and other pieces. And even if stock, is that stock to the corvette from the tune?

[LS ROB]

Is this thing on jack stands and does it have a full exhaust system or just open headers?

[BML72Nova]

Is this thing on jack stands and does it have a full exhaust system or just open headers?

full exhaust system, car is drivable.

[BML72Nova]

Aftermarket intake usually ends up meaning non-stock injectors and other pieces. And even if stock, is that stock to the corvette from the tune?

I can see the confusion, intake manifold is stock, it's just the filter/intake to the throttle body that was replace. Manifold etc has never been pulled off engine. tune is a starting tune using the stock corvette as template, done by current performance - most just VATS delete etc.

[gtstorey]

I assume from LS Rob’s 2007 Corvette comment indicates that the tune is 2007 Corvette, can’t look on my phone. Is the motor and everything on it from 2007 Corvette? Your posts aren’t clear on what you are running. You keep saying stock but you don’t say stock to what unless I’ve missed something.

[LS ROB]

I added a good bit to the maf and some to the vve. Try this and see if it makes a difference. Those changes were based off of the fuel trims showing lean. If that works better for you then you will just need to dial in VVE and MAF.

1972 - Nova LS Swap 6.0 maf vve-1.hpt

[BML72Nova]

I assume from LS Rob’s 2007 Corvette comment indicates that the tune is 2007 Corvette, can’t look on my phone. Is the motor and everything on it from 2007 Corvette? Your posts aren’t clear on what you are running. You keep saying stock but you don’t say stock to what unless I’ve missed something.

Everything is pulled from the same corvette that was in a rear end collision, ECM, Engine, harness etc. No modifications have been made to engine.

[BML72Nova]

I added a good bit to the maf and some to the vve. Try this and see if it makes a difference. Those changes were based off of the fuel trims showing lean. If that works better for you then you will just need to dial in VVE and MAF.

1972 - Nova LS Swap 6.0 maf vve-1.hpt

Thank you! I will check this out over the weekend and follow back up!

[BML72Nova]

ok, so it does run better - no longer stalls but still has a lot to be desired. Idle is very rough. Appreciate your help with this.
Attached is the cold start run from today. 2_Cold Start - Run to Closed Loop v3.hpl

[ns158sl]

It is in Open Loop at the beginning. Maybe i am blind, but i dont see why. Pull codes and see if anything pops up. Being it is stock, if fuel pressure is good (which should be verified), it should run fineish. You will/should adjust your MAF being it is a different intake tract. Tuning for headers usually is just adjusting O2 delay a little bit.

[LS ROB]

I made another pretty good sized change on the VVE and MAF. That should have you headed in the right direction. Just focus on dialing those in and it will come around.


1972 - Nova LS Swap 6.0 maf vve-1.1hpt.hpt

[BML72Nova]

I made another pretty good sized change on the VVE and MAF. That should have you headed in the right direction. Just focus on dialing those in and it will come around.


1972 - Nova LS Swap 6.0 maf vve-1.1hpt.hpt

I see what you are doing here, will load today. I really appreciate you taking the time, I obviously am a newbie when it comes to this and have gone down a rabbit hole of information that I didn't really know existed. So assuming this moves me in the right direction, then I want to focus on MAF tuning first then VVE? Several resources out there but thinking ill follow this guy's YouTube direction, he has this whole section on Gen IV that looks super helpful. https://youtube.com/playlist?list=PL...9yjxffDmoz0w1C

[LS ROB]

I see what you are doing here, will load today. I really appreciate you taking the time, I obviously am a newbie when it comes to this and have gone down a rabbit hole of information that I didn't really know existed. So assuming this moves me in the right direction, then I want to focus on MAF tuning first then VVE? Several resources out there but thinking ill follow this guy's YouTube direction, he has this whole section on Gen IV that looks super helpful. https://youtube.com/playlist?list=PL...9yjxffDmoz0w1C

You can do either one first. I'd probably start with VVE first then do the MAF. If you're really feeling confident, then you can find the thread about tuning MAF and VVE at the same time. As a beginner, i'd recommend the traditional way of failing the maf and tuning VVE then do MAF only. That way you learn the basics so to speak.