C6 LSR running lean

[smokehow]

LS2* Cant change titles here I guess.

First attempt at tuning, so I'm definitely green. Have read a hundred different threads here, watched every you tube video I could find, and have taken a crack at it.

Bought this c6 ls2 with a btr stage 3 cam, se long tubes / x pipe, and an aftermarket "cold air" intake.. The cam / headers were installed by a reputable shop, and tuned by same said shop (2005 c6 Base as found.hpt). Previous owner installed the cai some time after this, and then I got the car.

Immediately after getting the car home and doing some spirited driving, I started getting P0131/P0151 codes which tipped me off to a lean condition. Tested for vaccum leaks and found nothing. Tested fuel pressure, and it is fine, so assumed it was a tuning issue related to the change from stock intake system tha thte car was tuned on to the aftermarket system.

So I picked up a used mpvi2 and started logging. The lean condition seemed confirmed by high LTFTs. I started by tuning the MAF using LTFT+STFT error ratio, but decided I should pick up a wideband.

So now I have done several rounds of MAF tuning with the wideband, and have it dialed in quite well in my opinion (See 2005 c6 MAF Tuning AFE Intake 5.hpl).

I've copied the MAF cal tables back over to the "base" tune that came with the car, and dynamic airflow for now until I have a chance to dial in the VE table. (MAF Calibrated AFE SD Disabled.hpt). The car is idling terribly at startup if I have dynamic enabled after correctly tuning the MAF, so I figured I would run MAF only for now until I dial in the VE table.

To my rookie eyes, the EQ Ratio seems to trend consistently higher than Commanded EQ Ratio while cruising around after flashing this tune (MAF Calibrated AFE SD Disabled Cruise.hpl). Is this normal? To me I would expect to see it averaging at commanded EQ Ratio like I do in my MAF calibration datalogs. The "final" tune seems to oscillate a lot rather than staying flat which also leads me to believe something is wrong.

If this is not normal, any hints as to how to dial this down to be inline?

Thanks!

2005 c6 Base as found.hpt
2005 c6 MAF Tuning AFE Intake 5.hpl
MAF Calibrated AFE SD Disabled.hpt
MAF Calibrated AFE SD Disabled Cruise.hpl

[blindsquirrel]

Absolute ton pulled out of the VE, for... some reason? This is your table compared to stock. Yes I know 'stage 3' cam but still.
screenshot.01-06-2025 05.14.11.png

Generally recommended to do VE first, then MAF (if at all, depends on how well-behaved the cam is and if it's getting any reversion at the MAF).

No cats, but still has Post O2 & Cat tests enabled. If you're using recent/current version of the Editor you won't have those settings available. Still needs those turned off.

I'm always suspicious when someone says 'fuel pressure is good' without giving the number.

[edcmat-l1]

I'm always suspicious when someone says 'fuel pressure is good' without giving the number.

I recently got cussed out by a mail order customer I wanted him to put a FP gauge on his vehicle. Guy was so nasty I gave him a 100% refund without him even asking.

Sorry no other input lol

[smokehow]

Fuel pressure maintained 58-60psi on my princess auto gauge through a wot pull.

I know the ve table is a problem, hence disabling it (I think) by setting the dynamic airflow enable/disable RPMs low, which should put me to MAF only? The ve table came to me this way supposedly from a reputable tuner, but my first datalog attempt definitely shows that it's out of whack by a lot.

My MAF tuning logs have the WB EQ ratio a fairly smooth line, near commanded. With the fuel trims enabled in my tune, I am seeing this oscillation on the WB EQ ratio that I don't see when I have them disabled while datalogging for my MAF tuning.

I assume this is fuel trims doing this? But is that what I should expect to see, or is that a problem? If It's normal, is it also normal to see the WB EQ trending slightly lean? I'm seeing an average of about 1.025 while cruising. Not sure if that's any concern, or if it's totally fine.

I guess at the end of the day, I've never seen "good" WB EQ charts in a datalog to know if what I am seeing is a problem or not.

I've read something about an offset setting for the NB 02s that I may need to adjust to compensate for the changed position of the sensors with the long tubes. Is that a potential issue?

[smokehow]

Absolute ton pulled out of the VE, for... some reason? This is your table compared to stock. Yes I know 'stage 3' cam but still.
screenshot.01-06-2025 05.14.11.png

Generally recommended to do VE first, then MAF (if at all, depends on how well-behaved the cam is and if it's getting any reversion at the MAF).

No cats, but still has Post O2 & Cat tests enabled. If you're using recent/current version of the Editor you won't have those settings available. Still needs those turned off.

I'm always suspicious when someone says 'fuel pressure is good' without giving the number.

I found a stock 2005 tune file, and too noticed the difference in the VE table. My understanding that if it's breathing better, I should be after an increase on this table, is that correct or am I off-base?

Recommendations on a version of the editor I can use to adjust the o2 & cat settings mentioned?

[smokehow]

I recently got cussed out by a mail order customer I wanted him to put a FP gauge on his vehicle. Guy was so nasty I gave him a 100% refund without him even asking.

Sorry no other input lol

Yeah If the guy I am paying to tune my car thinks there's a fuel pressure issue, I'm not going to argue with him.

[blindsquirrel]

Yes, if an engine has breathing improvements that result in making more power then there should be bigger numbers in the VE. Smaller numbers would reflect less power - which a lumpy cam will have at low speed, generally only under 2500 or so though. Not through the entire range all the way out to 6800.

The only recommendation I can make here is, put some cats back on it and think bad thoughts towards whoever it was that took them off in the first place.

[smokehow]

Absolute ton pulled out of the VE, for... some reason? This is your table compared to stock. Yes I know 'stage 3' cam but still.
screenshot.01-06-2025 05.14.11.png

Generally recommended to do VE first, then MAF (if at all, depends on how well-behaved the cam is and if it's getting any reversion at the MAF).

No cats, but still has Post O2 & Cat tests enabled. If you're using recent/current version of the Editor you won't have those settings available. Still needs those turned off.

I'm always suspicious when someone says 'fuel pressure is good' without giving the number.

I decided to start my VE tuning running the base VE map from the stock C5 read I have. It was very rich, almost across the board.

I did 6 datalog sessions, primarily multiplying by 50% and then smoothing it out by hand, each time getting closer and closer to 0% EQ error.

My current VE table is now quite a bit different that the as-found from when I got the car:
Screenshot 2025-06-01 124922.png

And still a fair bit reduced from the factory file I have:
Screenshot 2025-06-01 125125.png

But, thus far it is running pretty great. At least at idle in my garage. The weather turned, so I did not had a chance to try this latest tune revision, but I am hopeful to see an improvement based solely on how the startup idle feels, something I was struggling with before.

Will report back after the next datalog.

[smokehow]

Why put cats back on? I live in a province that doesn't require inspections or emissions testing.

[blindsquirrel]

Why not dump your used antifreeze and used oil over the fence into your neighbor's yard? I mean, if you know they aren't going to give you any shit about it.

[edcmat-l1]

Lol

[Alvin]

To my rookie eyes, the EQ Ratio seems to trend consistently higher than Commanded EQ Ratio while cruising around after flashing this tune (MAF Calibrated AFE SD Disabled Cruise.hpl). Is this normal? To me I would expect to see it averaging at commanded EQ Ratio like I do in my MAF calibration datalogs. The "final" tune seems to oscillate a lot rather than staying flat which also leads me to believe something is wrong.

If this is not normal, any hints as to how to dial this down to be inline?

Thanks!

Sounds like what you are asking is..

With the fuel trims active my wideband is reading consistantly a bit lean.

This is normal. The o2's switch lean on purpose so O2 can burn what is in the cats. The average of that is slightly lean on a wideband.

The VE table doesn't look quite right to me FYI.

[smokehow]

Sounds like what you are asking is..

With the fuel trims active my wideband is reading consistently a bit lean.

This is normal. The o2's switch lean on purpose so O2 can burn what is in the cats. The average of that is slightly lean on a wideband.

The VE table doesn't look quite right to me FYI.

Appreciate the insight on the WB showing lean. That's reassuring.

I spent last Saturday dialing in the VE table, and the car is running quite well now. I didn't get much of a chance to log with my final tune, but after 9 rounds of logging and tweaking, I got most of the table within ~1% err running in open loop with MAF disabled.

What's your thoughts on the valley in my VE table between 1600 and 3200rpm? I read somewhere that this may be normal on a cammed LS, but I can't find that information again, and all the other e40 tunes I come across seem to have a stock VE table. Should I focus on smoothing the table out further, or is that a realistic looking table for a lightly modded engine?

Original tune;
Screenshot 2025-06-14 123117.png

After 9 rounds with the wideband:
Screenshot 2025-06-14 123101.png

9th round VE tuning EQ error table:
Screenshot 2025-06-14 123258.png


Final Tune
2005 C6 MAF VE Calibrated June 7.hpt